I haven't done this legwork yet because I thought you might want to be involved - finding a good target for observation is a substantial part of doing science! :)

Ideally, we'd pick a target for our observation using a combination of

searching ADS and/or SIMBAD for existing literature .... we want something that doesn't have a LOT of other references, but some references are fine - if someone else has already assembled data on an object, we might be able to use those data and/or results - we just don't want something that has already been "done to death." (page from the wiki on literature searching)
checking POSS and other existing multi-wavelength data to see what the object looks like in those bands .... does it look thick and dark in the optical? bright in the infrared? Both of those things suggest that it will be interesting with Spitzer. Something that looks diaphanous in the optical will likely turn out to be completely transparent with Spitzer. (page from the wiki on introduction to data at other wavelengths; you can also do this with Leopard -- see next item.)
and, checking to see if it is or is not in the Spitzer archive .... you need to use Leopard to do this. (page from the wiki on searching the archive using Leopard-- NB: "searching the archive to see what is there" is the same thing as "downloading data" except that when you search to see what is there, you don't actually download the data, you just see that there is something there.) Also, note that just because there is data already in the Archive on a given cloud doesn't mean it's a BAD thing, just that it's not a good thing for a new proposal. You should make a note of the "nice" ones you find, because you can go grab the data as soon as the data are public.

My original thoughts on good targets were the following three:

LDN 470
LDN 1225
LDN 880 (but maybe too diaphanous)

And, at the AAS, you guys also came up with

LDN 1340

The master list of objects that I worked from is here, courtesy of Babar Ali. Note that these are all opacity class 5 objects. Opacity class 5 or higher is what we probably want for Spitzer observations. None of these have many references in ADS. This is not meant to be a comprehensive list by any means, just a place to start. If you want to instead start with the complete Lynds Dark Nebulae catalog, it's here (the data are linked as "online data" or something similar).

Please post your thoughts and reactions to each of these targets, and any new ones you think are viable candidates for observation. For example, you might post a gif or jpeg of the POSS image you found, or a summary list of references (e.g., "3 papers besides Lynds, one radio, others submm" or whatever). Note the syntax I'm using to post comments on LDN 1340 below -- this is a method suggested by the Oil City folks, and I think it works really well to follow the conversation. See the help page linked from the left (above the search box) for hints on how do this.

LDN 470

LDN 1225

LDN 880

Here is the article I mentioned in our meeting earlier today.

THE ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 123:233È250, 1999 July (1999. The American Astronomical Society. All rights reserved. Printed in U.S.A. A CATALOG OF OPTICALLY SELECTED CORES CHANG WON LEE AND PHILIP C. MYERS Harvard-Smithsonian Center for Astrophysics, 60 Garden Street,MS 42, Cambridge, MA 02138; cwlee=cfa.harvard.edu, pmyers=cfa.harvard.edu Received 1998 October 7; accepted 1999 February 23 ABSTRACT We present a new catalog of 406 dense cores optically selected by using the STScI Digitized Sky Survey (DSS). In this catalog 306 cores have neither an embedded young stellar object (EYSO) nor a preÈmain-sequence (PMS) star, 94 cores have EYSOs (one core has both an EYSO and a PMS star), and six cores have PMS stars only. Our sample of dense cores in the catalog is fairly complete within a category of northern Lynds class 5 and 6 clouds and southern Hartley et al. class A clouds, providing a database useful for the systematic study of dense cores. Most of the cores listed in the catalog have diameters between 0.05 and 0.36 pc with a mean of D0.24 pc. The sizes (D0.33 pc in the mean) of cores with EYSOs are found to be usually larger than the sizes (D0.22 pc in the mean) of starless cores. The typical mean gas density of the cores is D7]103 cm~3. Most of the cores are more likely elongated than spherical (mean aspect ratio : D2.4). The ratio of the number of cores with EYSOs to the number of starless cores for our sample is about 0.3, suggesting that the typical lifetime of starless cores is 0.3È1.6 Myr, about 3 times longer than the duration of the class 0 and class I phases. This lifetime is shorter than expected from models of ambipolar di†usion, by factors of 2È44. Subject headings : catalogs È ISM: clouds È stars : preÈmain-sequence 1. INTRODUCTION Low-mass stars are generally believed to form through the inward gravitational collapse of ““ dense cores ÏÏ with density Z a few 104 cm~3, which are expected to form via ambipolar di†usion processes (Shu, Adams, & Lizano 1987; Ciolek & Mouschovias 1995). However, the knowledge of such simple processes in star formation is almost entirely theoretical because there is still very little direct observational support. It is therefore desirable to conduct unbiased systematic surveys of dense cores to search for evidence of core evolution and star-forming motion. The optical dark cloud catalogs of Lynds (1962), Feitzinger & Stu�we (1984), and Hartley et al. (1986, hereafter HMSTG), based on visual inspection of optical sky survey prints, have provided us the most basic and complete set of sources for the study of star-forming regions, although these catalogs themselves could not give accurate positions for a systematic survey of dense cores because the positions of dark regions were determined approximately by eye. Using these catalogs has served as a basis for making more accurate and detailed catalogs. For the northern hemisphere, Myers, Linke, & Benson (1983, hereafter MLB) have collected 90 small (angular size \5@) opaque spots through visual inspection of the Palomar Sky Atlas prints to conduct a systematic survey in 13CO, C18O (1È0) lines, and later NH (Benson & Myers 1989, hereafter BM). Clemens & Barvai3nis (1988, hereafter CB) have also identiÐed 248 molecular clouds with optical sizes smaller than 10@ by procedures similar to MLBÏs method. For the southern hemisphere, Vilas-Boas, Myers, & Fuller (1994) selected 101 condensations with average optical size less than 7@ and visual extinction greater than 2.5 mag from ESO J plates, visual extinction maps (Hetem, Sanzovo, & Lepine 1988), and the HMSTG catalog to observe them in the 13CO and C18O (1È0) lines. Bourke, Hyland, & Robinson (1995a) have compiled 169 Bok globuleÈlike small (\10@) dark clouds from visual inspection of the SERC Schmidt survey J plates primarily with the guidance of the HMSTG catalog and observed all the cores in the ammonia (1,1) line (Bourke et al. 1995b). These e†orts resulted in an excellent database for the observational study of low-mass star formation. However, the samples given in these catalogs were limited to a few regions, and many cores are still missing even toward the searched area, so these previous studies are not complete. Moreover, most opaque positions of the dark clouds in these catalogs were determined by eye, so that positions are not only very subjective but also not accurate enough for an efficient survey in molecular lines. Now, through the e†orts of the Space Telescope Science Institute (STScI), the Digitized Sky Survey (DSS) data are available for us. These data allow us to computerize the selection of cores and accurately determine their positions. With the guidance of the Lynds (1962) catalog for the northern sky and the Hartley et al. (1986) catalog for the southern sky, in addition to several reference catalogs that have been used for numerous molecular line studies (see ° 2 for detailed references), we created a new catalog of dense cores using the STScI DSS. Our catalog presents the most complete list of optically selected dense cores whose positions were accurately measured within a few arcseconds. The actual accuracy of positions is dependent only upon the procedures for smoothing the data and centering the intensity minima of the core. In the following section we describe in detail how we selected the cores. Then we analyze the statistics of the physical parameters of our sample and discuss the implications of core statistics for the present standard model of isolated star formation. Finally we summarize our results in ° 3. 2. THE CATALOG 2.1. Selection of Cores Our method for the selection of cores is to image an area, usually 0¡.5]0¡.5 and occasionally 1¡.0]1¡.0 around a reference position, and to make a contour map of optical 233 234 LEE & MYERS extinction to select the multiple local minimum positions of intensity. For guiding reference positions, we used the following: BM (NH peaks), Onishi et al. (1996 ; C18O peaks), Codella et al. (19937; NH peaks), Lemme et al. (1996; 3 NHpeaks), and Lynds (1962 ; every Lynds clouds with opacity 53 and 6) for northern clouds, and Vilas-Boas et al. (1994; C18O peaks) and HMSTG (clouds with density class A) for southern clouds (Table 1). Digitized data1 were retrieved from the STScI DSS using the ““ getimage ÏÏ software package provided by STScI. Image processing was conducted with the IRAF software package2 (Tody 1993). An accurate reading (within error of a few arcseconds) of coordinates of local intensity minima in the contour map overlapped in the gray image in IRAF was made possible by browsing images in World Coordinate Space (Mink 1995) with the ““ SAOimage ÏÏÈX11 window based image display program (VanHilst 1990). However, the real accuracy of our positions was dependent upon the grid size we used to make smooth contours and center the intensity minima of the core, usually about 15AÈ50A. In order to check the reliability of our method, we compared our new positions with peak positions of NH maps (with beam resolution of 87A) for 22 cores by BM. T3he di†erence [68@@^10@@ (mean^s.e.m.)] between the two positions was found to be smaller than the beam resolution of the NH maps, meaning that our method is fairly reliable for3 determining the intensity minima positions of new cores. Figure 1 shows one example of new core selection using the dark cloud, L1622. This example is typical in that several distinct intensity minima are obtained for each reference position. In total, we examined 250 reference positions (Table 1) and identiÐed 406 local maxima of optical extinction (Table 2), which we call cores. For all sources, we searched the IRAS Point Source Catalog using the ““ riras ÏÏ package (D. J.Mink 1998, private communication) to determine which sources have embedded IRAS point sources. In the search, we assumed the IRAS point source to be an ““ embedded ÏÏ young stellar object (EYSO) when it satisÐes all of the following criteria : 1. There should be detections in at least two of the four IRAS wavelength bands. 2. The detected Ñuxes (F) should be greater in the longer wavelength. However, IRAS point sources with F100km\ F60km or or were con- , F100km\F25kmsidered to be EYSO, s Fas100kmlo\ngF12akms F60km[ F25km[F12km. 3. The projected position of the IRAS source on the sky should be enclosed by the contour of the least extinction level of core in the optical image. 1 Images from the northern plates (POSS) were based on photographic data of the National Geographic SocietyÈPalomar Geographic Society to the California Institute of Technology, and images from the southern plates (SERC-J) were based on photographic data obtained using the UK Schmidt Telescope. The plates were processed into the present compressed digital form with their permission. The UK Schmidt Telescope was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council, until 1988 June, and thereafter by the Anglo-Australian Observatory. The Digitized Sky Survey was produced at the Space Telescope Science Institute under US government grant NAGW-2166. 2 IRAF is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation. With these criteria, we searched all cores to determine whether there are EYSOs within a box with a size of 2 times the geometric mean of the FWHM of a core. The FWHM of the core was obtained from an extinction contour map of the core as described in the next section. We found 94 sources with EYSOs and 306 cores without EYSOs. Our criteria are very similar to those of BMbut di†er from those of Beichman et al. (1986) and Wood, Myers, & Daugherty (1994) in that ours were designed to preferentially select embedded protostars (class 0 and class I YSOs) and therefore not to include preÈmain-sequence (PMS) stars. To Ðnd a possible PMS star, we used color-color diagram criteria in the 12, 25, and 60 km IRAS bands of Weintraub (1990) : [2.00\log (l12F12 and /l25 F25)/log (l12/l25)\1.35 [1.75\log (l25F25 Five /l60 F60)/log (l25/l60)\2.20. cores were found to have possible PMS stars. We also searched the catalog of PMS stars by Herbig & Bell (1988) in which PMS stars were identiÐed by optical spectroscopic data. From this search two more sources were found to include PMS stars within their projected extents. Thus we believe that seven sources may have PMS stars. We note that one of seven contains EYSO as well. In summary, of 406 identiÐed cores, 306 were found to have neither an EYSO nor a PMS star, 94 were found to have EYSOs (one core has both an EYSO and a PMS star), and six to have a PMS star only. Henceforth we call the 306 cores with neither an EYSO nor a PMS star ““ starless cores. ÏÏ In Table 2, column (9), the starless cores are marked as N and cores with EYSOs as Y, cores with a PMS star are marked as PM or PM* for a PMS star known by optical spectroscopy (Herbig & Bell 1988), and cores with both an EYSO and a PMS star are marked as Y/PM. The IRAS point sources and the PMS stars believed to be associated with our optically selected cores are listed in Table 3. 2.2. Statistics of Physical Parameters of Cores In this section we discuss the statistics of the physical parameters of cores. Our sample statistics are believed to be representative of the core properties since the cores were selected from Lynds class 5 and 6 and HMSTGÏs class A, which, taken together, comprise a nearly complete set of the densest and the most opaque clouds in the sky. We present several physical parameters of the optically selected cores in Table 2. The sizes of the major axis (a in col. [5] of Table 2) and the minor axis (b in col. [6] of Table 2), and position angle (PA in col. [8] of Table 2) of the FWHM of the cores were approximately measured by an ellipse template, ruler, and protractor. The minus and plus signs in column (8) mean clockwise and counterclockwise with respect to equatorial north, respectively. The largest errors for these parameters are from the uncertainties in the selection of the background level of the core that determines the size of the FWHM of the core and in the eye Ðtting of the ellipse template to the core. The errors obtained by repeating measurements are usually within about 10% of the size in the size measurement and within about 5¡ in the PA measurement. For the sources that are not elliptical in shape, their ““ equivalent ÏÏ diameters (R in col. [7] of Table 2) were measured. The equivalent diameter of a core is deÐned as 2](A/n)0.5, where A is the area within the FWHM contour of the core. Following are our results and discussion on the statistics of these physical parameters. TABLE 1 SEARCHED REFERENCE REGIONS Regiona R.A. (1950) Decl. (1950) Referenceb Nc Regiona R.A. (1950) Decl. (1950) Referenceb Nc L1291 . . . . . . . . . . . . . . . . 00 39 47.6 61 44 35 Lynds 1 L260 . . . . . . . . . . . . . . . . . 16 44 22.3 [09 30 02 BM 1 L1333 . . . . . . . . . . . . . . . . 02 21 10.2 75 13 32 Lynds 1 L158* . . . . . . . . . . . . . . . 16 44 42.0 [13 54 03 BM 6 L1355 . . . . . . . . . . . . . . . . 02 48 41.4 68 43 36 Lynds 1 L204BC* . . . . . . . . . . . . 16 44 51.0 [12 09 00 BM 6 L1358 . . . . . . . . . . . . . . . . 02 51 00.0 69 10 00 Lynds 2 L191 . . . . . . . . . . . . . . . . . 16 44 59.2 [12 35 31 BM 2 L1450D . . . . . . . . . . . . . 03 25 18.8 30 53 02 BM 1 L255 . . . . . . . . . . . . . . . . . 16 45 01.9 [09 48 32 Lynds 2 B5 . . . . . . . . . . . . . . . . . . . . 03 45 16.3 32 44 59 BM 1 L234 . . . . . . . . . . . . . . . . . 16 45 38.0 [10 56 00 BM 3 CB 17 . . . . . . . . . . . . . . . 04 00 35.0 56 48 00 Le 1 L162 . . . . . . . . . . . . . . . . . 16 46 40.0 [14 04 10 Lynds 2 L1498 . . . . . . . . . . . . . . . . 04 07 50.0 25 02 13 BM 1 L63 . . . . . . . . . . . . . . . . . . 16 47 21.0 [18 01 00 BM 4 L1495 . . . . . . . . . . . . . . . . 04 15 18.0 28 25 00 ON 2 L141 . . . . . . . . . . . . . . . . . 16 48 03.1 [15 16 54 Lynds 3 L1506B . . . . . . . . . . . . . . 04 16 03.9 25 13 01 Lynds 1 L129 . . . . . . . . . . . . . . . . . 16 52 18.4 [16 17 10 Lynds 1 L1506A . . . . . . . . . . . . . . 04 20 18.0 24 54 00 ON 1 L122 . . . . . . . . . . . . . . . . . 16 52 22.4 [16 42 03 Lynds 1 L1399 . . . . . . . . . . . . . . . . 04 20 27.0 54 51 00 Lynds 3 L146 . . . . . . . . . . . . . . . . . 16 53 37.0 [15 55 00 Lynds 1 L1521B . . . . . . . . . . . . . . 04 20 48.0 26 31 40 BM 2 CB 68 . . . . . . . . . . . . . . . 16 53 52.0 [16 00 00 Le 3 B213-7 . . . . . . . . . . . . . . . 04 22 24.0 26 24 00 ON 1 DC 3504]44 . . . . . . . 16 59 40.9 [34 20 44 HMSTG 1 B217 . . . . . . . . . . . . . . . . . 04 24 42.5 26 11 13 BM 2 L111 . . . . . . . . . . . . . . . . . 17 11 59.5 [20 27 15 Lynds 1 L1521 . . . . . . . . . . . . . . . . 04 25 36.0 26 45 00 ON 2 L100 . . . . . . . . . . . . . . . . . 17 13 07.6 [20 54 04 Lynds 1 L1407 . . . . . . . . . . . . . . . . 04 25 37.6 54 07 35 Lynds 1 L173 . . . . . . . . . . . . . . . . . 17 14 25.4 [18 27 45 Lynds 1 L1400AK . . . . . . . . . . . 04 25 47.0 54 48 00 BM 4 L1768 . . . . . . . . . . . . . . . 17 17 00.0 [26 49 00 Lynds 2 L1521E . . . . . . . . . . . . . . 04 26 17.0 26 07 47 BM 1 L1773 . . . . . . . . . . . . . . . 17 18 08.4 [26 50 46 Lynds 1 L1524 . . . . . . . . . . . . . . . . 04 26 22.0 24 26 30 ON 4 L1774 . . . . . . . . . . . . . . . 17 19 32.1 [27 02 25 Lynds 1 L1445 . . . . . . . . . . . . . . . . 04 28 28.8 46 31 01 Lynds 1 B68 . . . . . . . . . . . . . . . . . . 17 20 23.0 [23 47 13 BM 3 L1551S . . . . . . . . . . . . . . 04 28 40.0 18 01 52 BM 2 DC 3463[41 . . . . . . . 17 22 40.3 [42 37 01 HMSTG 1 B18-2 . . . . . . . . . . . . . . . . 04 29 00.0 24 35 53 ON 1 DC 3479[44 . . . . . . . 17 28 52.7 [41 32 37 HMSTG 1 TMC 2 . . . . . . . . . . . . . . 04 29 13.0 24 20 14 BM 4 L425 . . . . . . . . . . . . . . . . . 17 44 15.4 [04 34 07 Lynds 1 L1536B . . . . . . . . . . . . . . 04 29 54.0 22 52 00 ON 2 DC 3475[80 . . . . . . . 17 44 26.1 [43 42 02 HMSTG 1 L1536A . . . . . . . . . . . . . . 04 30 26.0 22 36 10 BM 1 L392 . . . . . . . . . . . . . . . . . 17 50 24.3 [08 26 43 Lynds 1 B18-3 . . . . . . . . . . . . . . . . 04 30 53.7 24 05 09 ON 1 L421 . . . . . . . . . . . . . . . . . 17 51 38.9 [05 46 02 Lynds 1 B18-4 . . . . . . . . . . . . . . . . 04 32 36.0 24 02 00 ON 2 L460 . . . . . . . . . . . . . . . . . 17 55 24.4 [03 46 24 Lynds 1 L1527 . . . . . . . . . . . . . . . . 04 36 00.0 26 10 00 Lynds 2 L432 . . . . . . . . . . . . . . . . . 17 55 46.2 [05 43 45 Lynds 1 L1534 . . . . . . . . . . . . . . . . 04 36 31.2 25 35 56 BM 1 L468 . . . . . . . . . . . . . . . . . 17 57 38.0 [03 30 03 Lynds 1 CB 22 . . . . . . . . . . . . . . . 04 37 25.0 29 48 57 Le 1 L462 . . . . . . . . . . . . . . . . . 18 04 48.0 [04 42 08 Lynds 1 TMC 1 . . . . . . . . . . . . . . 04 38 19.0 25 45 30 BM 2 L108 . . . . . . . . . . . . . . . . . 18 07 08.0 [28 18 41 Lynds 1 L1507A . . . . . . . . . . . . . . 04 39 29.0 29 38 07 CO 2 L422 . . . . . . . . . . . . . . . . . 18 09 20.0 [08 04 46 Lynds 1 L1507B . . . . . . . . . . . . . . 04 39 53.4 29 38 25 Lynds 3 L436-8 . . . . . . . . . . . . . . 18 11 39.1 [07 16 18 Lynds 2 L1426 . . . . . . . . . . . . . . . . 04 43 17.5 52 59 03 Lynds 1 L323 . . . . . . . . . . . . . . . . . 18 12 39.1 [18 11 47 Lynds 1 L1517 . . . . . . . . . . . . . . . . 04 52 07.2 30 33 18 BM 4 L490-2 . . . . . . . . . . . . . . 18 12 30.0 [03 46 40 Lynds 2 L1512 . . . . . . . . . . . . . . . . 05 00 54.4 32 39 00 BM 1 CB 130 . . . . . . . . . . . . . . 18 13 38.0 [02 33 52 Le 3 L1544 . . . . . . . . . . . . . . . . 05 01 14.0 25 07 00 BM 3 L328 . . . . . . . . . . . . . . . . . 18 14 06.7 [18 03 54 Lynds 1 L1523 . . . . . . . . . . . . . . . . 05 03 02.7 31 37 30 Lynds 1 L429 . . . . . . . . . . . . . . . . . 18 14 49.7 [08 15 50 Lynds 4 CB 28 . . . . . . . . . . . . . . . 05 03 51.0 [04 00 00 Le 1 L483 . . . . . . . . . . . . . . . . . 18 15 00.0 [04 40 00 Lynds 2 L1552 . . . . . . . . . . . . . . . . 05 14 34.9 26 01 17 Lynds 1 L466 . . . . . . . . . . . . . . . . . 18 17 04.5 [06 07 36 Lynds 1 L1582A . . . . . . . . . . . . . . 05 28 30.0 12 28 20 BM 1 L451 . . . . . . . . . . . . . . . . . 18 19 12.3 [07 14 11 Lynds 1 B35A . . . . . . . . . . . . . . . . 05 41 45.3 09 07 40 BM 1 L539 . . . . . . . . . . . . . . . . . 18 21 24.0 [01 06 00 Lynds 2 L1622 . . . . . . . . . . . . . . . . 05 52 00.0 01 51 00 Lynds 2 L416 . . . . . . . . . . . . . . . . . 18 22 46.2 [10 41 26 Lynds 1 L1621 . . . . . . . . . . . . . . . . 05 53 02.0 02 10 27 Lynds 2 L406 . . . . . . . . . . . . . . . . . 18 22 50.5 [11 49 11 Lynds 1 CB 37 . . . . . . . . . . . . . . . 05 57 24.0 31 39 26 Le 1 L423 . . . . . . . . . . . . . . . . . 18 25 03.9 [10 16 08 Lynds 1 L1574 . . . . . . . . . . . . . . . . 06 04 48.0 18 30 00 Lynds 1 L411 . . . . . . . . . . . . . . . . . 18 25 07.9 [11 29 15 Lynds 1 L1645 . . . . . . . . . . . . . . . . 06 05 16.0 [05 33 00 Lynds 1 L503 . . . . . . . . . . . . . . . . . 18 26 49.5 [04 40 45 Lynds 1 L1578 . . . . . . . . . . . . . . . . 06 05 33.0 18 07 00 BM 2 L443 . . . . . . . . . . . . . . . . . 18 30 00.0 [09 10 00 Lynds 2 CB 45 . . . . . . . . . . . . . . . 06 06 00.0 17 50 52 Le 1 L239 . . . . . . . . . . . . . . . . . 18 30 11.5 [26 04 16 Lynds 1 L1633 . . . . . . . . . . . . . . . . 06 22 00.0 03 30 00 Lynds 1 L588 . . . . . . . . . . . . . . . . . 18 33 00.0 [00 35 00 Lynds 1 DC 2592[132 . . . . . . 07 29 30.0 [46 51 00 HMSTG 2 L495 . . . . . . . . . . . . . . . . . 18 36 32.6 [06 41 06 Lynds 1 DC 2555[48 . . . . . . . 08 03 46.1 [39 00 10 HMSTG 1 L648 . . . . . . . . . . . . . . . . . 18 37 15.0 12 41 50 Lynds 2 V13-14. . . . . . . . . . . . . . . 08 07 39.0 [35 55 54 VMP 4 L530D . . . . . . . . . . . . . . 18 47 18.0 [04 53 20 BM 3 DC 2573[25 . . . . . . . 08 15 23.0 [39 43 36 HMSTG 2 L549 . . . . . . . . . . . . . . . . . 18 59 29.8 [05 23 08 Lynds 1 DC 2660[75 . . . . . . . 08 19 53.7 [49 41 10 HMSTG 2 L567 . . . . . . . . . . . . . . . . . 19 01 32.0 [04 30 00 BM 1 DC 2674[75 . . . . . . . 08 24 17.0 [50 52 12 HMSTG 2 B133 . . . . . . . . . . . . . . . . . 19 03 25.3 [06 57 20 BM 1 DC 2672[72 . . . . . . . 08 25 03.5 [50 30 11 HMSTG 1 CB 180 (L531) . . . . . . 19 03 31.0 [06 58 07 Le 1 DC 2676[60 . . . . . . . 08 32 38.0 [50 08 00 HMSTG 2 L581 . . . . . . . . . . . . . . . . . 19 04 55.5 [03 59 32 Lynds 1 DC 2694]30 . . . . . . . 09 20 28.7 [45 35 05 HMSTG 1 L709 . . . . . . . . . . . . . . . . . 19 11 37.3 16 22 01 Lynds 1 DC 2695]40 . . . . . . . 09 24 18.1 [44 58 32 HMSTG 1 DC 13[205 . . . . . . . . 19 13 12.4 [36 42 20 HMSTG 1 DC 2742[04 . . . . . . . 09 27 05.5 [51 23 14 HMSTG 1 L763 . . . . . . . . . . . . . . . . . 19 16 45.9 23 21 45 Lynds 1 DC 2962[158 . . . . . . 10 49 28.9 [76 48 59 HMSTG 1 L730 . . . . . . . . . . . . . . . . . 19 17 40.5 19 51 09 Lynds 2 DC 2965[157 . . . . . . 10 55 31.7 [76 48 52 HMSTG 1 L655 . . . . . . . . . . . . . . . . . 19 17 47.2 08 23 33 Lynds 1 DC 29103[35 . . . . . . 10 57 12.9 [63 26 49 HMSTG 1 L673-1-10 . . . . . . . . . . . 19 18 45.0 11 22 00 Lynds 10 TABLE 1ÈContinued Regiona R.A. (1950) Decl. (1950) Referenceb Nc Regiona R.A. (1950) Decl. (1950) Referenceb Nc DC 2971[161 . . . . . . 11 01 04.0 [77 25 48 HMSTG 2 L673-11 . . . . . . . 19 18 45.0 11 05 00 Lynds 1 DC 2972[151 . . . . . . 11 09 09.7 [76 37 16 HMSTG 1 L673-12 . . . . . . . 19 18 45.0 10 50 00 Lynds 3 DC 2983[131 . . . . . . 11 37 59.1 [75 00 00 HMSTG 1 L771 . . . . . . . . . . . 19 18 46.3 23 25 13 Lynds 1 DC 2977[28 . . . . . . . 11 59 07.2 [64 52 15 HMSTG 1 L684 . . . . . . . . . . . 19 19 16.1 12 23 25 Lynds 1 Mu 4 . . . . . . . . . . . . . . . . 12 21 29.0 [71 35 56 VMP 1 L677 . . . . . . . . . . . 19 19 40.0 11 25 00 Lynds 4 DC 3002[35 . . . . . . . 12 21 30.2 [65 55 26 HMSTG 1 L774 . . . . . . . . . . . 19 21 15.0 23 20 00 Lynds 2 Mu 8 . . . . . . . . . . . . . . . . 12 26 39.0 [70 54 04 VMP 2 L769 . . . . . . . . . . . 19 22 15.0 23 00 00 Lynds 4 DC 3007[10 . . . . . . . 12 28 50.6 [63 28 02 HMSTG 1 L698 . . . . . . . . . . . 19 23 37.5 12 59 48 Lynds 1 DC 3023[177 . . . . . . 12 32 17.0 [80 16 18 HMSTG 3 L778 . . . . . . . . . . . 19 25 16.0 23 40 19 Lynds 4 DC 3025[175 . . . . . . 12 37 03.2 [80 03 39 HMSTG 1 B335 . . . . . . . . . . . 19 34 33.3 07 27 00 BM 1 DC 3026[159 . . . . . . 12 41 21.4 [78 31 56 HMSTG 1 L694 . . . . . . . . . . . 19 38 18.0 10 54 44 Lynds 3 DC 3029[141 . . . . . . 12 46 14.9 [76 40 50 HMSTG 1 L758 . . . . . . . . . . . 19 44 12.8 18 54 47 Lynds 1 Ch 5 . . . . . . . . . . . . . . . . . 12 46 38.7 [76 41 04 VMP 1 L880 . . . . . . . . . . . 20 11 49.4 40 03 59 Lynds 1 DC 3030[143 . . . . . . 12 49 14.6 [76 56 33 HMSTG 1 L1152 . . . . . . . . . 20 35 24.0 67 43 53 BM 1 Ch 17 . . . . . . . . . . . . . . . . 12 56 14.0 [77 00 00 VMP 4 L1041 . . . . . . . . . 20 36 05.5 57 33 36 Lynds 1 DC 3036[145 . . . . . . 12 59 11.0 [77 06 44 HMSTG 2 L922 . . . . . . . . . . . 20 36 22.0 44 19 07 Lynds 1 DC 3037[148 . . . . . . 13 01 39.7 [77 26 49 HMSTG 2 L917 . . . . . . . . . . . 20 38 30.0 43 58 00 Lynds 2 DC 3037[150 . . . . . . 13 01 55.0 [77 36 42 HMSTG 2 L1049 . . . . . . . . . 20 40 00.0 57 20 00 Lynds 2 DC 3038[142 . . . . . . 13 03 36.4 [76 44 48 HMSTG 1 L1148 . . . . . . . . . 20 40 00.0 67 11 00 BM 2 DC 3162]51 . . . . . . . 14 22 33.6 [55 07 04 HMSTG 1 L896 . . . . . . . . . . . 20 40 28.8 39 42 22 Lynds 2 DC 3148[51 . . . . . . . 14 44 23.4 [65 04 41 HMSTG 1 L1155C . . . . . . . 20 43 00.0 67 41 44 BM 3 DC 3230]40 . . . . . . . 15 07 35.6 [53 06 36 HMSTG 1 L915 . . . . . . . . . . . 20 43 23.0 42 58 52 Lynds 1 DC 3382]164 . . . . . . 15 37 21.0 [34 29 18 HMSTG 2 L1082C . . . . . . . 20 49 36.0 60 07 40 BM 3 DC 3272]18 . . . . . . . 15 38 33.4 [52 38 36 HMSTG 1 L1082AB . . . . . . 20 52 20.7 60 03 14 BM 2 DC 3388]165 . . . . . . 15 39 25.0 [33 52 00 HMSTG 6 L981 . . . . . . . . . . . 20 58 38.0 50 05 09 Lynds 3 DC 3392]161 . . . . . . 15 42 01.0 [34 08 00 HMSTG 4 L971 . . . . . . . . . . . 20 59 15.8 49 07 34 Lynds 2 DC 3389]151 . . . . . . 15 43 49.0 [35 04 30 HMSTG 2 L1174 . . . . . . . . . 20 59 46.3 68 01 04 BM 1 L134A . . . . . . . . . . . . . . . 15 50 58.1 [04 26 36 BM 1 L1172A . . . . . . . 21 01 45.0 67 35 13 BM 3 L183 . . . . . . . . . . . . . . . . . 15 51 35.7 [02 40 54 BM 1 L1063 . . . . . . . . . 21 06 44.6 56 06 09 Lynds 1 DC 3386]119 . . . . . . 15 53 26.0 [37 41 12 HMSTG 2 B361 . . . . . . . . . . . 21 10 35.0 47 12 01 BM 2 DC 3356]82 . . . . . . . 15 54 42.3 [42 26 57 HMSTG 1 L1125 . . . . . . . . . 21 14 07.0 61 27 10 Lynds 2 DC 3391]117 . . . . . . 15 55 22.0 [37 31 12 HMSTG 2 L944 . . . . . . . . . . . 21 15 54.0 43 05 41 Lynds 3 DC 3364]82 . . . . . . . 15 58 00.0 [41 50 00 HMSTG 2 L952-3 . . . . . . . . 21 18 51.0 43 13 00 Lynds 3 DC 3369]83 . . . . . . . 15 59 05.3 [41 31 30 HMSTG 1 L1021 . . . . . . . . . 21 20 34.8 50 50 17 Lynds 1 DC 3386]95 . . . . . . . 16 01 09.6 [39 29 37 HMSTG 1 L1014-1 . . . . . . . 21 22 20.6 49 56 52 Lynds 2 DC 3346]46 . . . . . . . 16 02 54.2 [45 46 25 HMSTG 1 L1099 . . . . . . . . . 21 34 27.9 57 13 18 Lynds 2 DC 3394]95 . . . . . . . 16 04 27.0 [39 04 06 HMSTG 1 L973 . . . . . . . . . . . 21 35 16.3 43 06 57 Lynds 1 DC 3376]76 . . . . . . . 16 04 58.6 [41 32 54 HMSTG 1 L1111 . . . . . . . . . 21 38 53.6 57 34 24 Lynds 1 DC 3397]92 . . . . . . . 16 06 45.0 [38 58 24 HMSTG 3 L1121 . . . . . . . . . 21 39 10.0 58 02 33 Lynds 1 DC 3381]71 . . . . . . . 16 07 59.4 [41 34 19 HMSTG 3 L1103 . . . . . . . . . 21 40 40.6 56 30 00 Lynds 2 DC 3402]90 . . . . . . . 16 08 01.0 [38 53 49 HMSTG 1 L1113 . . . . . . . . . 21 42 56.7 56 56 25 Lynds 2 DC 3369]51 . . . . . . . 16 10 18.3 [43 53 34 HMSTG 1 L1031C . . . . . . . 21 44 35.6 47 04 20 BM 1 DC 3420]94 . . . . . . . 16 14 28.7 [37 23 52 HMSTG 1 L1139 . . . . . . . . . 21 53 47.3 58 20 14 Lynds 2 DC 3412]65 . . . . . . . 16 21 44.4 [39 52 38 HMSTG 1 L1143 . . . . . . . . . 21 57 03.0 58 42 25 Lynds 1 L1681A* . . . . . . . . . . . . 16 23 59.0 [24 27 32 BM 1 L1166 . . . . . . . . . 22 03 46.7 59 19 07 Lynds 1 L1681B . . . . . . . . . . . . . . 16 24 33.8 [24 36 47 BM 1 L1164 . . . . . . . . . 22 05 07.7 58 51 15 Lynds 1 L1696AB . . . . . . . . . . . . 16 25 30.0 [24 12 32 BM 3 L1235 . . . . . . . . . 22 14 41.4 73 10 00 BM 1 L1704 . . . . . . . . . . . . . . . . 16 27 50.0 [23 34 37 BM 2 L1195 . . . . . . . . . 22 25 18.1 61 01 06 Lynds 1 L1757 . . . . . . . . . . . . . . . . 16 29 01.9 [19 35 24 Lynds 2 L1221 . . . . . . . . . 22 26 38.4 68 45 48 Lynds 1 L1709BC* . . . . . . . . . . 16 29 16.0 [23 51 12 BM 4 L1185 . . . . . . . . . 22 27 27.6 58 53 30 Lynds 1 L1689AB* . . . . . . . . . . 16 30 10.5 [24 37 57 BM 6 L1251A . . . . . . . 22 29 03.3 74 58 51 BM 2 DC 3387]18 . . . . . . . 16 30 33.3 [44 54 53 HMSTG 1 L1197 . . . . . . . . . 22 35 08.0 58 41 46 Lynds 1 L43 . . . . . . . . . . . . . . . . . . 16 31 27.7 [15 41 40 BM 3 L1251 . . . . . . . . . 22 36 26.0 74 54 46 Lynds 1 DC 3460]78 . . . . . . . 16 33 32.0 [35 31 06 HMSTG 2 L1229 . . . . . . . . . 23 12 16.8 61 46 47 Lynds 1 DC 3464]79 . . . . . . . 16 34 13.4 [35 08 26 HMSTG 1 L1234 . . . . . . . . . 23 15 12.0 62 10 00 Lynds 1 DC 3463]78 . . . . . . . 16 34 26.8 [35 21 54 HMSTG 1 CB 243 . . . . . . . . 23 23 00.0 63 20 00 Le 1 L121 . . . . . . . . . . . . . . . . . 16 36 41.0 [13 59 21 Lynds 1 L1262A . . . . . . . 23 23 32.2 74 01 45 BM 1 L1782 . . . . . . . . . . . . . . . . 16 39 13.2 [19 36 22 Lynds 2 CB 246 . . . . . . . . 23 54 12.0 58 17 47 Le 1 DC 3393[03 . . . . . . . 16 42 30.0 [45 54 54 HMSTG 1 L1263 . . . . . . . . . 23 54 54.2 64 32 27 Lynds 1 DC 3405]05 . . . . . . . 16 43 05.8 [44 26 04 HMSTG 1 L1271 . . . . . . . . . 23 59 15.3 67 01 48 Lynds 4 NOTE.ÈUnits of right ascension are hours, minutes, and seconds, and units of declination are degrees, arcminutes, and arcseconds. a Searched size of all regions is 30@]30@ except for the Ðve regions marked with an asterisk behind the name of the region, whose searched area is 60@]60@. b REFERENCES.ÈLynds, Lynds 1962; BM, Benson & Myers 1989; Le, Lemme et al. 1996; ON, Onishi et al. 1996; CO, Codella et al. 1997; HMSTG, Hartley et al. 1986; VMP, Vilas-Boas et al. 1994. c Number of cores selected in each reference region. L1622 A B OPTICALLY SELECTED CORES 237 FIG. 1.ÈAn example (for L1622) of how to select the local minimum positions of the intensity in a cloud by its optical extinction using an image extracted from the STScI Digitized Sky Survey. The area of the image is and the coordinate of 0¡.5]0¡.5 the center is (a, d) 52m 01¡ 51@ 00@@), which was 1950.0\(5h 00s.0, changed from the Lynds (1962) position to shift the cloud into a central position in the image. The smooth contours are overlaid on the gray-scale image to enable identiÐcation of two local minima (A and B) of intensity. The smoothing length for the contours in this case is 30A. The regions with the locally lowest or highest intensity are marked with L and H, respectively. The numeric values below the characters are data values by DSS that are proportional to photographic densities. 2.2.1. T he Darkness Contrast of Cores In Table 2, column (10), we give an indication of a darkness contrast (DC) of the dark core to the background in the DSS image. This contrast was calculated according to (IB[IC)/IB, where IB and IC are the data values (DN) by DSS (that are on a scale of photographic density [c] in the expression c\DN/6553.4 [Postman 1996]) for the background and the core, respectively. The IB and IC values were approximately determined by using a cut-proÐle of the data values crossing the core. The IB and IC would correspond to a constantly Ñat level and a minimum level of the proÐle, respectively. Figure 2 shows an example of how we adopted IB and IC for L1622. This cut-proÐle is the one crossing two intensity minima of L1622A and L1622B. According to this value of the DC, we classiÐed cores into four quartiles, 1 being the least dark to 4 the most dark so that each group contains 25% of total number of cores. It is noted that the Lynds 6 and HMSTG A clouds more likely consist of cores with a DC of 3 or 4, while Lynds 5 clouds more likely have cores with a DC of 1 or 2 (Fig. 3). However we also note that if the dark cores are located at the dark background, the DC values tend to have a low value. This explains why many Lynds 6 cores also have a DC value of 1 in Figure 3. 2.2.2. T he Size and the AspectRatio of Cores For evaluation of these properties, we do not consider cores with more than two peaks in the contour map because of ambiguity in the size information of such cores, but we do consider cores with only one peak in the map whose size and aspect ratio can be better determined. The distribution of the apparent angular size of cores is shown with the geometric mean (ab)0.5 of cores in Figure 4, indicating that most of the cores (D70%) have angular size between 1@ and TABLE 2 OPTICALLY SELECTED CORES a b R PA Distance Number Source R.A. (1950) Decl. (1950) (arcmin) (arcmin) (arcmin) (deg) EYSO DC Class (pc) References (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) 1 . . . . . . . . L1275 00 00 48.2 67 02 05 8.2 1.5 3.5 25 N 4 5 . . . . . . 2 . . . . . . . . L1291 00 39 47.6 61 44 35 1.5 1.5 1.5 0 N 2 5 . . . . . . 3 . . . . . . . . L1333 02 21 10.2 75 13 32 2.8 1.7 2.2 2 N 3 6 . . . . . . 4 . . . . . . . . L1355 02 48 41.4 68 43 36 3.5 1.6 2.4 8 N 3 6 300 1 5 . . . . . . . . L1358-1 02 51 13.3 69 01 38 1.9 1.4 1.6 14 Y 2 6 . . . . . . 6 . . . . . . . . L1358-2 02 51 55.1 69 12 03 2.8 1.3 1.9 [87 N 2 6 . . . . . . 7 . . . . . . . . B5-1 03 44 26.4 32 46 45 3.2 1.6 2.3 [43 N 1 . . . 350 2 8 . . . . . . . . B5-2 03 45 15.5 32 45 07 2.1 1.8 1.9 24 N 1 . . . 350 2 9 . . . . . . . . CB 17 (L1389) 04 00 35.4 56 47 50 1.7 0.6 1.0 [44 Y 3 6 170 3 10 . . . . . . L1498 04 07 51.8 25 01 35 3.2 1.6 2.3 [71 N 1 5 140 4 11 . . . . . . L1495-2 04 14 51.2 28 30 40 6.3 5.1 5.7 7 N 3 5 140 4 12 . . . . . . L1495-3 04 15 23.9 28 21 21 12.0 5.7 8.3 15 Y 3 5 140 4 13 . . . . . . L1506B 04 16 03.9 25 13 01 7.9 2.2 4.2 [85 N 1 6 140 4 14 . . . . . . L1399-1 04 20 00.5 55 01 00 . . . . . . 6.2 . . . N 1 5 170 3 15 . . . . . . L1506A 04 20 30.1 24 58 29 20.2 9.5 13.9 [64 Y 2 6 140 4 16 . . . . . . L1521B-2 04 20 32.8 26 33 11 . . . . . . 6.2 . . . N 2 4 140 4 17 . . . . . . L1399-2 04 20 58.3 54 52 48 . . . . . . 9.2 . . . N 2 5 170 3 18 . . . . . . L1521B-1 04 21 11.6 26 29 12 4.7 4.7 4.7 0 N 2 4 140 4 19 . . . . . . L1399-3 04 21 11.8 54 49 59 . . . . . . 9.2 . . . N 2 5 170 3 20 . . . . . . B213-7 04 22 12.8 26 26 10 . . . . . . 5.4 . . . N 1 . . . 140 4 21 . . . . . . B217-1 04 24 44.5 26 11 27 3.2 1.7 2.3 [21 Y 1 . . . 140 4 22 . . . . . . B217-2 04 25 04.5 26 14 16 3.3 1.9 2.5 38 N 2 . . . 140 4 23 . . . . . . L1400A-2 04 25 05.8 54 39 40 4.1 1.3 2.3 [81 N 3 3 170 3 24 . . . . . . L1521-1 (L1521F) 04 25 29.0 26 45 04 6.9 4.4 5.5 [55 N 1 4 140 4 25 . . . . . . L1400F (L1407) 04 25 37.0 54 07 23 15.2 10.1 12.4 65 N 2 3 170 3 26 . . . . . . L1524-2 04 26 16.9 24 25 02 6.3 5.2 5.7 [86 Y 2 5 140 4 27 . . . . . . L1521E 04 26 17.2 26 07 34 2.7 1.7 2.1 90 N 1 4 140 4 28 . . . . . . L1524-1 04 26 17.8 24 31 26 6.5 3.6 4.8 [71 Y 2 5 140 4 29 . . . . . . L1521-2 04 26 26.8 26 53 27 5.5 2.5 3.7 [69 N 1 4 140 4 30 . . . . . . L1400K 04 26 41.6 54 44 16 . . . . . . 5.2 . . . N 4 3 170 3 31 . . . . . . L1524-3 04 26 51.5 24 23 44 10.8 5.4 7.6 [36 Y 2 5 140 4 32 . . . . . . L1524-4 04 27 04.1 24 18 47 10.8 5.4 7.6 [36 N 2 5 140 4 33 . . . . . . L1551S-2 04 28 03.5 18 09 09 5.7 3.8 4.7 [11 N 1 6 140 4 34 . . . . . . L1445 04 28 28.8 46 31 01 8.2 2.2 4.2 [10 N 2 5 . . . . . . 35 . . . . . . TMC 2-2 (L1529) 04 28 35.8 24 17 29 4.6 2.1 3.1 63 Y 1 5 140 4 36 . . . . . . L1551S-1 04 28 53.9 18 01 14 2.8 1.3 1.9 [41 N 1 6 140 4 37 . . . . . . TMC 2A (L1529) 04 28 59.1 24 25 42 9.5 4.7 6.7 [40 Y 1 5 140 4 38 . . . . . . B18-2 04 29 34.4 24 45 46 3.8 1.7 2.5 [55 N 2 . . . 140 4 39 . . . . . . TMC 2-1 (L1529) 04 29 37.5 24 18 14 . . . . . . 7.0 . . . Y 1 5 140 4 40 . . . . . . L1536-2 04 29 50.7 22 53 29 2.7 2.0 2.3 [2 N 1 4 140 4 41 . . . . . . TMC 2-3 (L1529) 04 29 57.6 24 11 26 4.3 2.5 3.3 [70 N 1 5 140 4 42 . . . . . . L1536-3 04 30 01.7 22 47 41 2.4 0.9 1.5 76 N 1 4 140 4 43 . . . . . . L1536-1 04 30 19.7 22 36 51 11.4 5.1 7.6 [88 N 1 4 140 4 44 . . . . . . B18-3 04 31 04.6 24 03 32 7.9 1.9 3.9 [55 N 3 . . . 140 4 45 . . . . . . B18-4 04 32 34.0 24 02 48 4.1 3.8 3.9 2 Y 3 . . . 140 4 46 . . . . . . B18-5 04 32 49.7 24 03 15 3.0 2.1 2.5 [37 N 2 . . . 140 4 47 . . . . . . L1527A-1 04 35 05.1 26 08 37 7.6 4.4 5.8 [75 Y 1 6 140 4 48 . . . . . . L1527A-2 04 35 54.0 26 15 38 4.0 1.5 2.4 5 N 1 6 140 4 49 . . . . . . L1534 04 36 36.4 25 35 14 9.5 6.3 7.7 [73 Y 1 5 140 4 50 . . . . . . CB 22 (L1503) 04 37 30.2 29 47 13 4.7 1.7 2.8 [43 N 2 5 140 4 51 . . . . . . TMC 1-1 (L1527) 04 38 26.5 25 39 27 15.8 4.7 8.6 [40 Y 2 6 140 4 52 . . . . . . TMC 1C (L1527) 04 38 27.5 25 55 46 12.6 5.7 8.5 [52 Y 2 6 140 4 53 . . . . . . L1507-1 04 39 29.4 29 36 24 4.7 2.2 3.2 [13 N 2 5 140 4 54 . . . . . . L1507-2 04 39 53.4 29 38 25 3.5 1.6 2.4 71 N 1 5 140 4 55 . . . . . . L1507-3 04 40 21.4 29 33 37 1.7 0.9 1.2 38 N 2 5 140 4 56 . . . . . . L1426 04 43 17.5 52 59 03 2.1 2.1 2.1 0 N 1 5 170 3 57 . . . . . . L1517C 04 51 33.6 30 30 54 4.7 3.2 3.9 [69 N 2 6 140 4 58 . . . . . . L1517B-2 04 51 56.4 30 38 03 3.2 2.1 2.6 [45 N 1 6 140 4 59 . . . . . . L1517A 04 51 56.7 30 29 20 4.7 2.5 3.4 [64 N 2 6 140 4 60 . . . . . . L1517B-1 04 52 05.9 30 32 58 4.7 1.7 2.8 [4 N 3 6 140 4 61 . . . . . . L1517D 04 52 45.7 30 35 14 4.7 2.4 3.4 [45 N 2 6 140 4 62 . . . . . . L1544-3 05 00 38.6 25 14 18 4.7 2.4 3.4 90 N 1 6 140 4 63 . . . . . . L1512 (CB 27) 05 00 54.4 32 39 00 4.7 2.2 3.2 [13 N 3 6 140 4 64 . . . . . . L1544-1 05 01 18.3 25 07 29 . . . . . . 5.8 . . . N 1 6 140 4 65 . . . . . . L1544-2 05 01 39.1 25 07 30 2.4 1.9 2.1 [60 N 1 6 140 4 238 TABLE 2ÈContinued a b R PA Distance Number Source R.A. (1950) Decl. (1950) (arcmin) (arcmin) (arcmin) (deg) EYSO DC Class (pc) References (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) 66 . . . . . . . L1523 05 03 02.7 31 37 30 5.1 1.9 3.1 12 N 2 6 140 4 67 . . . . . . . CB 28 05 03 51.2 [04 00 20 3.6 2.4 2.9 83 N 2 . . . 500 5 68 . . . . . . . L1552 05 14 34.9 26 01 17 5.9 2.5 3.8 [1 N 3 6 140 4 69 . . . . . . . L1582A 05 29 15.0 12 28 57 5.2 2.4 3.5 [52 N 4 5 400 6 70 . . . . . . . B35A 05 41 50.5 09 09 17 3.2 1.6 2.3 11 Y 2 . . . 400 7 71 . . . . . . . L1622A 05 52 17.1 01 56 55 5.1 1.1 2.4 39 N 3 6 500 5 72 . . . . . . . L1622B 05 52 17.5 01 45 11 2.2 1.1 1.6 87 Y 3 6 500 5 73 . . . . . . . L1621-2 05 52 49.8 02 08 07 1.0 0.8 0.9 90 N 2 4 500 5 74 . . . . . . . L1621-1 05 53 23.0 02 17 39 5.9 1.1 2.5 25 N 3 4 500 5 75 . . . . . . . CB 37 (L1555) 05 57 29.9 31 39 25 4.7 3.1 3.8 [87 N 3 4 . . . . . . 76 . . . . . . . L1574 06 05 08.9 18 28 41 2.5 0.9 1.5 [11 N 1 4 . . . . . . 77 . . . . . . . L1645 06 05 16.2 [05 32 16 4.9 1.3 2.5 6 Y 1 4 830 9 78 . . . . . . . L1578-2 06 05 40.4 18 12 00 13.3 5.7 8.7 7 PM* 3 4 . . . . . . 79 . . . . . . . L1578-1 06 05 41.6 18 06 54 13.3 5.7 8.7 7 PM* 2 4 . . . . . . 80 . . . . . . . CB 45 (L1578) 06 06 02.0 17 50 48 2.4 1.6 2.0 [38 N 3 4 . . . . . . 81 . . . . . . . L1633 06 22 04.0 03 23 53 1.4 1.4 1.4 0 N 3 4 . . . . . . 82 . . . . . . . DC 2592[132-1 (V4) 07 29 02.8 [46 37 10 1.6 0.5 0.9 88 N 4 A 300 10 83 . . . . . . . DC 2592[132-2 (V4) 07 29 20.3 [46 49 26 2.2 1.6 1.9 [31 N 3 A 300 10 84 . . . . . . . DC 2555[48 08 03 46.1 [39 00 10 5.2 0.9 2.2 86 N 3 A 300 10 85 . . . . . . . V13-2 08 06 54.9 [35 54 21 2.5 1.4 1.9 [54 N 4 A 300 10 86 . . . . . . . V13-3 08 07 01.0 [35 48 22 3.2 0.7 1.5 [28 N 4 A 300 10 87 . . . . . . . V13-1 08 07 09.0 [35 52 18 0.8 0.6 0.7 7 N 4 A 300 10 88 . . . . . . . V14 08 07 39.9 [35 56 04 . . . . . . 1.8 . . . Y 4 A 300 10 89 . . . . . . . DC 2573[25-1 08 15 19.5 [39 44 40 2.5 1.6 2.0 43 Y 4 A 300 10 90 . . . . . . . DC 2573[25-2 08 15 23.8 [39 41 40 1.3 0.9 1.1 39 N 3 A 300 10 91 . . . . . . . DC 2660[75-2 08 19 40.0 [49 31 38 . . . . . . 5.0 . . . Y 3 A 300 10 92 . . . . . . . DC 2660[75-1 08 19 53.7 [49 41 10 . . . . . . 7.0 . . . N 3 A 300 10 93 . . . . . . . DC 2674[75 08 24 15.2 [50 52 08 5.6 2.4 3.7 32 Y 4 A 300 10 94 . . . . . . . DC 2672[72 08 25 03.5 [50 30 11 . . . . . . 2.0 . . . Y 4 A 300 10 95 . . . . . . . DC 2675[74 08 25 10.2 [50 52 00 1.9 1.1 1.4 4 N 4 A 300 10 96 . . . . . . . DC 2676[60-1 08 32 36.6 [50 08 03 1.9 1.1 1.4 [73 N 4 A 300 10 97 . . . . . . . DC 2676[60-2 08 32 45.3 [50 14 33 1.4 0.8 1.1 32 N 4 A 300 10 98 . . . . . . . DC 2694]30 (V27) 09 20 28.7 [45 35 05 8.1 1.6 3.6 [34 N 4 A 300 10 99 . . . . . . . DC 2695]40 09 24 18.1 [44 58 32 6.3 0.9 2.4 72 N 3 A 300 10 100 . . . . . . DC 2742[04 09 27 05.5 [51 23 14 4.6 1.9 3.0 12 N 4 A 300 10 101 . . . . . . DC 2962[158 10 49 28.9 [76 48 59 . . . . . . 4.6 . . . N 3 A 150 11 102 . . . . . . DC 2965[157 10 55 31.7 [76 48 52 4.7 1.9 3.0 [2 N 2 A 150 11 103 . . . . . . DC 29103[35 10 57 12.9 [63 26 49 10.7 2.5 5.2 [76 N 1 A . . . . . . 104 . . . . . . DC 2971[161-1 11 01 09.3 [77 26 22 9.5 3.2 5.5 34 N 3 A 150 11 105 . . . . . . DC 2971[161-2 11 01 39.8 [77 32 55 . . . . . . 5.8 . . . N 3 A 150 11 106 . . . . . . DC 2972[151 11 09 47.9 [76 38 29 10.1 4.7 6.9 [48 N 2 A 150 11 107 . . . . . . DC 2983[131 11 37 59.1 [75 00 00 3.5 2.7 3.1 [56 N 3 A 150 11 108 . . . . . . DC 2977[28 11 59 07.2 [64 52 15 6.9 3.2 4.7 [47 Y 1 A 175 12 109 . . . . . . Mu 4 12 21 29.0 [71 35 56 3.9 0.8 1.8 25 N 1 A 225 13 110 . . . . . . DC 3002[35 12 21 30.2 [65 55 26 7.3 1.3 3.1 [78 N 1 A 175 12 111 . . . . . . Mu 8 12 26 39.0 [70 54 04 8.4 1.0 2.9 39 N 1 A 225 13 112 . . . . . . Mu 10 12 28 03.4 [70 46 30 . . . . . . 8.4 . . . N 1 A 225 13 113 . . . . . . DC 3020[177-1 12 28 22.6 [80 19 54 2.8 1.3 1.9 [40 N 3 A 200 14 114 . . . . . . DC 3007[10 (Co2) 12 28 50.6 [63 28 02 10.1 6.6 8.2 [32 N 1 A 175 12 115 . . . . . . DC 3023[177 12 31 54.0 [80 13 31 3.3 1.6 2.3 26 N 3 A 200 14 116 . . . . . . DC 3020[177-2 12 33 06.8 [80 20 35 1.9 1.3 1.6 48 N 3 A 200 14 117 . . . . . . DC 3025[175 12 37 03.2 [80 03 39 3.0 0.6 1.3 52 N 3 A 200 14 118 . . . . . . DC 3026[159 12 41 21.4 [78 31 56 2.1 1.3 1.7 [51 N 3 A 200 14 119 . . . . . . Ch 5 12 46 38.7 [76 41 04 9.3 3.5 5.7 65 N 2 A 200 14 120 . . . . . . DC 3030[143 (Ch 7) 12 49 14.6 [76 56 33 8.5 6.0 7.1 [59 Y 1 A 200 14 121 . . . . . . Ch 17 12 54 44.8 [76 56 34 5.7 3.2 4.3 [32 N 2 A 200 14 122 . . . . . . Ch 19-2 12 56 59.5 [77 02 36 9.5 3.8 6.0 [24 N 2 A 200 14 123 . . . . . . Ch 19-1 12 57 24.1 [76 57 01 9.5 3.8 6.0 [24 Y 2 A 200 14 124 . . . . . . Ch 20 12 59 18.9 [77 06 56 2.8 1.7 2.2 [32 N 2 A 200 14 125 . . . . . . DC 3037[145 13 01 12.6 [77 09 35 4.6 2.8 3.6 17 N 2 A 200 14 126 . . . . . . DC 3037[148 13 01 39.7 [77 26 49 3.2 1.6 2.3 [22 N 1 A 200 14 127 . . . . . . DC 3037[152 13 01 51.6 [77 45 01 . . . . . . 5.0 . . . N 2 A 200 14 128 . . . . . . DC 3037[150 13 02 00.5 [77 37 08 4.7 3.7 4.2 0 N 2 A 200 14 129 . . . . . . DC 3038[142 13 03 36.4 [76 44 48 4.7 2.4 3.4 78 Y 2 A 200 14 130 . . . . . . DC 3162]51 14 22 33.6 [55 07 04 . . . . . . 4.8 . . . N 4 A . . . . . . 131 . . . . . . DC 3148[51 14 44 23.4 [65 04 41 10.1 2.2 4.7 [82 Y 1 A 170 15 239 TABLE 2ÈContinued a b R PA Distance Number Source R.A. (1950) Decl. (1950) (arcmin) (arcmin) (arcmin) (deg) EYSO DC Class (pc) References (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) 132 . . . . . . DC 3230]40 15 07 35.6 [53 06 36 2.4 1.1 1.6 55 N 3 A . . . . . . 133 . . . . . . DC 3379]164 15 36 25.2 [34 36 48 3.8 2.8 3.3 [18 Y 3 A 170 16 134 . . . . . . DC 3382]164 15 37 23.9 [34 30 40 4.7 2.1 3.1 4 N 4 A 170 16 135 . . . . . . DC 3272]18 15 38 33.4 [52 38 36 . . . . . . 3.0 . . . N 4 A . . . . . . 136 . . . . . . DC 3388]165-2 15 39 08.8 [33 41 27 4.1 3.2 3.6 [67 N 3 A 170 16 137 . . . . . . DC 3388]165-3 15 39 29.2 [33 42 30 5.7 2.5 3.8 [50 N 3 A 170 16 138 . . . . . . DC 3388]165-4 15 39 32.4 [33 59 44 . . . . . . 8.8 . . . Y 3 A 170 16 139 . . . . . . DC 3388]165-5 15 39 49.9 [33 59 18 . . . . . . 8.8 . . . Y 3 A 170 16 140 . . . . . . DC 3388]165-6 15 40 06.5 [34 04 01 2.5 1.9 2.2 [86 N 2 A 170 16 141 . . . . . . DC 3392]161-1 15 41 42.7 [34 08 10 10.1 5.7 7.6 40 Y 3 A 170 16 142 . . . . . . DC 3392]161-2 15 42 01.1 [34 03 59 4.1 2.5 3.2 52 N 3 A 170 16 143 . . . . . . DC 3392]161-3 15 42 03.2 [34 11 21 2.4 1.4 1.8 [72 N 3 A 170 16 144 . . . . . . DC 3392]161-4 15 42 16.9 [34 15 19 6.5 3.6 4.8 19 N 3 A 170 16 145 . . . . . . DC 3389]151 15 43 24.3 [35 02 46 7.9 1.4 3.3 [47 N 3 A 170 16 146 . . . . . . DC 3390]150 15 44 46.3 [35 03 29 5.1 2.2 3.3 [7 Y 4 A 170 16 147 . . . . . . L134A 15 50 49.0 [04 25 00 4.9 4.9 4.9 0 N 1 5 165 17 148 . . . . . . L183 15 51 22.8 [02 40 44 6.3 3.8 4.9 51 N 2 5 165 17 149 . . . . . . DC 3386]119-1 15 53 25.0 [37 45 27 6.5 2.4 3.9 21 N 3 A 170 16 150 . . . . . . DC 3386]119-2 15 53 40.4 [37 39 54 5.1 3.2 4.0 64 Y 4 A 170 16 151 . . . . . . DC 3356]82 15 54 42.3 [42 26 57 7.1 1.7 3.5 [88 N 3 A 170 16 152 . . . . . . DC 3391]117-1 15 55 22.3 [37 30 42 2.5 1.6 2.0 71 N 4 A 170 16 153 . . . . . . DC 3391]117-2 15 55 45.6 [37 28 26 4.1 2.4 3.1 33 N 4 A 170 16 154 . . . . . . DC 3364]82 15 57 26.9 [41 55 44 17.7 11.1 14.0 90 N 4 A 170 16 155 . . . . . . DC 3367]82 15 58 00.8 [41 44 44 15.8 3.8 7.7 57 N 4 A 170 16 156 . . . . . . DC 3369]83 15 59 05.3 [41 31 30 6.3 2.8 4.2 [31 N 4 A 170 16 157 . . . . . . DC 3386]95 16 01 09.6 [39 29 37 . . . . . . 4.0 . . . N 4 A 170 16 158 . . . . . . DC 3346]46 16 02 54.2 [45 46 25 6.9 3.8 5.1 44 N 2 A 170 16 159 . . . . . . DC 3394]95 16 04 27.0 [39 04 06 4.3 2.4 3.2 [29 N 3 A 170 16 160 . . . . . . DC 3376]76 16 04 58.6 [41 32 54 8.2 3.8 5.6 22 N 4 A 170 16 161 . . . . . . DC 3397]92-1 16 06 19.9 [39 01 37 . . . . . . 11.8 . . . Y 3 A 170 16 162 . . . . . . DC 3397]92-2 16 06 45.1 [38 55 58 . . . . . . 11.8 . . . Y 3 A 170 16 163 . . . . . . DC 3397]92-3 16 07 01.5 [39 03 00 . . . . . . 11.8 . . . Y 3 A 170 16 164 . . . . . . DC 3381]71 16 07 59.4 [41 34 19 14.5 8.2 10.9 80 N 3 A 170 16 165 . . . . . . DC 3402]90-1 16 08 01.0 [38 53 49 . . . . . . 8.2 . . . PM 3 A 170 16 166 . . . . . . DC 3402]90-2 16 08 15.2 [38 50 38 . . . . . . 8.2 . . . PM 3 A 170 16 167 . . . . . . DC 3402]90-3 16 08 23.4 [38 53 56 . . . . . . 8.2 . . . PM 3 A 170 16 168 . . . . . . DC 3369]51 16 10 18.3 [43 53 34 11.4 3.2 6.0 [60 N 3 A 170 16 169 . . . . . . DC 3420]94 16 14 28.7 [37 23 52 4.4 3.3 3.8 [11 N 3 A 170 16 170 . . . . . . DC 3412]65 16 21 44.4 [39 52 38 11.4 3.2 6.0 [52 N 1 A 170 16 171 . . . . . . L1681A 16 23 58.5 [24 27 39 . . . . . . 26.6 . . . Y 4 5 165 17 172 . . . . . . L1696B-1 16 24 40.3 [24 06 24 . . . . . . 11.0 . . . Y 4 6 165 17 173 . . . . . . L1696A 16 25 27.5 [24 12 48 . . . . . . 11.0 . . . N 4 6 165 17 174 . . . . . . L1696B-2 16 26 09.4 [24 06 43 6.6 3.8 5.0 [35 N 4 6 165 17 175 . . . . . . L1704-1 16 27 49.8 [23 35 49 4.9 3.2 4.0 32 N 4 6 165 17 176 . . . . . . L1704-2 16 28 09.3 [23 34 29 3.3 1.7 2.4 [17 N 4 6 165 17 177 . . . . . . L1709B-1 16 28 35.4 [23 52 19 44.2 7.6 18.3 54 Y 4 6 165 17 178 . . . . . . L1757-1 16 29 01.9 [19 35 24 . . . . . . 11.0 . . . N 3 6 165 17 179 . . . . . . L1757-2 16 29 08.5 [19 42 05 . . . . . . 11.0 . . . N 3 6 165 17 180 . . . . . . L1689A 16 29 10.4 [24 56 03 2.8 1.6 2.1 11 N 2 6 165 17 181 . . . . . . L1689B2 16 29 11.4 [24 18 43 9.8 3.6 5.9 [14 Y 3 6 165 17 182 . . . . . . L1709B-2 16 29 49.3 [23 46 22 44.2 7.6 18.3 54 N 4 6 165 17 183 . . . . . . L1709C-2 16 30 18.0 [23 40 01 44.2 7.6 18.3 54 N 4 6 165 17 184 . . . . . . L1689B3 16 30 26.5 [24 37 33 9.5 4.7 6.7 81 N 4 6 165 17 185 . . . . . . L1689B4 16 30 27.0 [24 21 55 7.6 4.4 5.8 [64 Y 4 6 165 17 186 . . . . . . DC 3387]18 16 30 33.3 [44 54 53 9.5 1.4 3.6 [66 Y 3 A 700 32 187 . . . . . . L1709C-1 16 30 52.6 [23 33 54 44.2 7.6 18.3 54 N 4 6 165 17 188 . . . . . . L1689B5 16 30 55.8 [24 28 16 . . . . . . 17.4 . . . Y 3 6 165 17 189 . . . . . . L43F 16 31 03.9 [15 45 31 21.8 1.9 6.4 64 N 3 6 165 17 190 . . . . . . L43D 16 31 28.8 [15 42 54 21.8 1.9 6.4 64 Y 3 6 165 17 191 . . . . . . L1689B1 16 31 35.2 [24 29 47 . . . . . . 17.4 . . . Y 4 6 165 17 192 . . . . . . L43E 16 31 47.7 [15 40 51 21.8 1.9 6.4 64 Y 3 6 165 17 193 . . . . . . DC 3460]78 16 33 34.7 [35 30 27 4.1 2.1 2.9 5 N 4 A 170 16 194 . . . . . . DC 3464]79 16 34 13.4 [35 08 26 3.8 2.4 3.0 [51 N 4 A 170 16 195 . . . . . . DC 3463]78 16 34 26.8 [35 21 54 5.9 1.7 3.2 32 N 4 A 170 16 196 . . . . . . L121 16 36 41.0 [13 59 21 3.1 1.7 2.3 8 N 1 5 165 17 197 . . . . . . L1782-1 16 39 13.2 [19 36 22 6.0 1.7 3.2 [40 N 1 6 165 17 240 TABLE 2ÈContinued a b R PA Distance Number Source R.A. (1950) Decl. (1950) (arcmin) (arcmin) (arcmin) (deg) EYSO DC Class (pc) References (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) 198 . . . . . . L1782-2 16 39 36.4 [19 38 00 3.8 2.7 3.2 35 N 2 6 165 17 199 . . . . . . DC 3393-03 16 42 30.0 [45 54 54 4.3 1.4 2.5 [87 N 4 A 700 32 200 . . . . . . DC 3405]05 16 43 05.8 [44 26 04 7.1 2.5 4.2 62 N 4 A 700 32 201 . . . . . . L158-2 16 44 02.6 [13 53 26 8.2 4.1 5.8 55 N 2 6 165 17 202 . . . . . . L204C-1 16 44 30.6 [12 14 14 5.7 2.2 3.5 1 N 3 6 165 17 203 . . . . . . L260 16 44 32.5 [09 29 58 7.6 4.1 5.6 [73 Y 2 6 165 17 204 . . . . . . L204C-2 16 44 58.5 [12 18 04 3.6 1.6 2.4 [5 N 3 6 165 17 205 . . . . . . L191-1 16 44 59.6 [12 34 43 6.0 2.5 3.9 [52 N 2 5 165 17 206 . . . . . . L191-2 16 45 01.7 [12 47 38 1.7 1.4 1.5 58 N 1 5 165 17 207 . . . . . . L255-1 16 45 01.9 [09 48 32 6.3 4.0 5.0 54 Y 3 6 165 17 208 . . . . . . L234E1 16 45 22.6 [10 52 10 11.7 0.9 3.2 2 N 3 3 165 17 209 . . . . . . L234E2 16 45 23.2 [10 46 37 11.7 0.9 3.2 2 Y 2 3 165 17 210 . . . . . . L255-2 16 45 30.9 [09 58 47 4.9 1.9 3.1 [5 N 2 6 165 17 211 . . . . . . L158-3 16 45 33.9 [14 03 18 7.9 4.1 5.7 54 Y 3 6 165 17 212 . . . . . . L234E3 16 45 49.0 [10 45 45 3.3 2.1 2.6 56 N 2 3 165 17 213 . . . . . . L158-4 16 46 22.0 [14 05 23 7.0 3.5 4.9 81 Y 2 6 165 17 214 . . . . . . L162-1 16 46 22.3 [14 05 33 . . . . . . 7.6 . . . Y 1 6 165 17 215 . . . . . . L63-4 16 46 49.1 [17 49 47 3.2 1.6 2.3 [49 N 1 6 165 17 216 . . . . . . L63-3 16 47 10.5 [17 53 51 5.2 1.4 2.7 [25 N 1 6 165 17 217 . . . . . . L63-2 16 47 11.2 [17 59 52 5.9 3.6 4.6 [82 N 1 6 165 17 218 . . . . . . L63-1 16 47 20.5 [18 00 53 5.9 3.6 4.6 [82 N 1 6 165 17 219 . . . . . . L141-2 16 48 03.1 [15 16 54 . . . . . . 6.8 . . . N 2 5 165 17 220 . . . . . . L141-3 16 48 11.1 [15 12 04 6.9 1.9 3.6 54 N 2 5 165 17 221 . . . . . . L129-2 16 51 57.6 [16 21 42 2.5 1.1 1.7 25 N 1 6 165 17 222 . . . . . . L129-1 16 52 18.4 [16 17 10 3.5 1.6 2.4 [79 N 1 6 165 17 223 . . . . . . L122 16 52 22.4 [16 42 03 3.0 2.1 2.5 80 N 2 6 165 17 224 . . . . . . CB 68-3 (L146) 16 53 05.4 [15 52 21 11.4 7.9 9.5 [25 Y 2 5 165 17 225 . . . . . . CB 68-2 (L146) 16 54 00.0 [15 57 11 2.8 1.3 1.9 [5 N 1 5 165 17 226 . . . . . . CB 68-1 (L146) 16 54 27.5 [16 04 09 4.1 2.1 2.9 [40 Y 2 5 165 17 227 . . . . . . DC 3504]44 16 59 40.9 [34 20 44 8.8 6.9 7.8 0 N 1 A 170 16 228 . . . . . . L111 17 11 59.5 [20 27 15 4.3 1.4 2.5 66 N 1 6 165 17 229 . . . . . . L100 17 13 07.6 [20 54 04 12.3 4.7 7.6 [21 Y/PM 1 6 165 17 230 . . . . . . L173 17 14 25.4 [18 27 45 9.5 3.2 5.5 [11 N 1 6 165 17 231 . . . . . . L1772 17 16 25.8 [26 41 37 9.3 3.6 5.8 53 N 1 6 165 17 232 . . . . . . L1768 17 16 35.0 [26 52 57 13.0 1.6 4.6 81 N 1 6 165 17 233 . . . . . . L1773 17 18 08.4 [26 50 46 12.0 4.4 7.3 [45 N 1 6 165 17 234 . . . . . . L1774 17 19 32.1 [27 02 25 7.9 3.2 5.0 [82 Y 1 6 165 17 235 . . . . . . B68-1 17 19 36.0 [23 47 13 3.8 2.4 3.0 [48 N 2 . . . 165 17 236 . . . . . . B68-2 17 20 34.0 [23 37 32 4.3 3.5 3.9 [26 N 2 . . . 165 17 237 . . . . . . B68-3 17 20 49.4 [23 39 57 8.2 2.5 4.5 45 N 2 . . . 165 17 238 . . . . . . DC 3463[41 17 22 40.3 [42 37 01 12.6 4.4 7.4 62 PM 1 A . . . . . . 239 . . . . . . DC 3479[44 17 28 52.7 [41 32 37 . . . . . . 3.6 . . . N 2 A . . . . . . 240 . . . . . . L425 17 44 15.4 [04 34 07 . . . . . . 6.6 . . . Y 1 5 . . . . . . 241 . . . . . . DC 3475[80 17 44 26.1 [43 42 02 5.2 2.5 3.6 [81 N 1 A . . . . . . 242 . . . . . . L392 17 50 24.3 [08 26 43 6.5 2.7 4.2 33 N 1 5 200 18 243 . . . . . . L421 17 51 38.9 [05 46 02 1.6 1.6 1.6 0 N 1 5 200 18 244 . . . . . . L460 17 55 24.4 [03 46 24 7.6 3.2 4.9 [52 N 1 6 200 18 245 . . . . . . L432 17 55 46.2 [05 43 45 10.1 3.2 5.7 [8 N 1 6 200 18 246 . . . . . . L468 17 57 38.0 [03 30 03 4.7 2.1 3.1 0 N 1 5 200 18 247 . . . . . . L462-1 18 04 51.9 [04 43 57 4.9 2.1 3.2 90 N 1 6 200 18 248 . . . . . . L462-2 18 04 56.9 [04 40 57 4.9 3.2 4.0 81 N 1 6 200 18 249 . . . . . . L108 18 07 08.0 [28 18 41 2.8 1.4 2.0 [11 N 3 6 . . . . . . 250 . . . . . . L422 18 09 20.0 [08 04 46 4.2 1.6 2.6 [36 N 2 6 . . . . . . 251 . . . . . . L438 18 11 23.8 [07 10 01 3.2 1.7 2.3 [49 N 1 6 . . . . . . 252 . . . . . . L436 18 11 53.0 [07 23 49 4.6 2.2 3.2 85 N 1 6 . . . . . . 253 . . . . . . L323 (CB 125) 18 12 39.1 [18 11 47 . . . . . . 10.4 . . . Y 2 6 200 8 254 . . . . . . L490 18 12 42.5 [03 47 11 3.3 2.2 2.7 [48 N 1 6 200 18 255 . . . . . . L492 18 13 11.6 [03 47 17 3.8 2.7 3.2 [18 N 1 6 200 18 256 . . . . . . CB 130-2 (L507) 18 13 37.5 [02 24 28 2.2 1.4 1.8 16 N 3 5 200 18 257 . . . . . . CB 130-1 (L507) 18 13 39.2 [02 34 06 3.1 1.4 2.1 [88 N 3 5 200 18 258 . . . . . . CB 130-3 (L507) 18 13 41.5 [02 17 47 3.0 1.3 2.0 61 N 3 5 200 18 259 . . . . . . L328 18 14 05.3 [18 03 10 1.7 1.4 1.5 47 N 1 6 200 8 260 . . . . . . L429-1 18 14 28.2 [08 14 40 21.5 8.8 13.8 42 N 2 6 200 18 261 . . . . . . L429-2 18 14 32.8 [08 19 02 21.5 8.8 13.8 42 N 2 6 200 18 262 . . . . . . L429-3 18 14 50.8 [08 15 17 21.5 8.8 13.8 42 N 2 6 200 18 263 . . . . . . L483-1 18 14 54.8 [04 40 23 . . . . . . 11.4 . . . Y 1 6 200 18 241 TABLE 2ÈContinued a b R PA Distance Number Source R.A. (1950) Decl. (1950) (arcmin) (arcmin) (arcmin) (deg) EYSO DC Class (pc) References (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) 264 . . . . . . L429-4 18 15 05.2 [08 10 07 21.5 8.8 13.8 42 N 2 6 200 18 265 . . . . . . L483-2 18 15 26.5 [04 34 24 7.4 4.4 5.7 51 N 1 6 200 18 266 . . . . . . L466 18 17 04.5 [06 07 36 6.3 5.1 5.7 45 N 1 6 200 18 267 . . . . . . L451 18 19 12.3 [07 14 11 6.8 2.8 4.4 74 N 1 5 200 18 268 . . . . . . L539-1 18 21 05.7 [01 04 28 . . . . . . 9.4 . . . N 1 6 200 18 269 . . . . . . L539-2 18 21 46.5 [01 01 05 . . . . . . 5.2 . . . N 1 6 200 18 270 . . . . . . L416 18 22 46.2 [10 41 26 . . . . . . 3.4 . . . N 3 6 200 18 271 . . . . . . L406 18 22 50.5 [11 49 11 10.1 7.6 8.8 26 Y 3 5 200 18 272 . . . . . . L423 18 25 03.9 [10 16 08 7.9 1.9 3.9 [82 N 1 5 200 18 273 . . . . . . L411 18 25 07.9 [11 29 15 3.0 0.8 1.5 34 N 3 5 200 18 274 . . . . . . L503 18 26 49.5 [04 40 45 . . . . . . 7.0 . . . N 2 6 200 18 275 . . . . . . L443-1 18 29 47.1 [08 59 13 4.1 2.8 3.4 14 N 3 5 200 18 276 . . . . . . L443-2 18 30 01.6 [09 14 41 5.2 4.6 4.9 [37 N 3 5 200 18 277 . . . . . . L239 18 30 11.5 [26 04 16 3.0 2.4 2.7 [58 N 1 6 . . . . . . 278 . . . . . . L443-3 18 30 12.0 [09 16 52 5.2 4.6 4.9 [37 N 2 5 200 18 279 . . . . . . L588-2 18 32 47.0 [00 43 53 . . . . . . 3.8 . . . N 3 6 200 18 280 . . . . . . L588-3 18 33 18.2 [00 33 25 2.4 1.3 1.8 61 N 3 6 200 18 281 . . . . . . L588-4 18 33 39.2 [00 40 38 1.1 0.6 0.8 78 N 3 6 200 18 282 . . . . . . L495 18 36 32.6 [06 41 06 4.9 2.4 3.4 86 N 1 6 200 18 283 . . . . . . L648-1 18 37 09.7 12 38 37 . . . . . . 6.4 . . . N 4 6 . . . . . . 284 . . . . . . L648-2 18 37 20.5 12 47 05 . . . . . . 6.4 . . . N 4 6 . . . . . . 285 . . . . . . L530D-3 18 46 48.0 [05 03 12 6.6 4.0 5.1 11 N 1 6 350 19 286 . . . . . . L530D-1 18 47 20.5 [04 51 55 16.1 6.9 10.5 5 N 1 6 350 19 287 . . . . . . L530D-2 18 47 22.1 [04 43 25 16.1 6.9 10.5 5 N 1 6 350 19 288 . . . . . . L549 18 59 29.8 [05 23 08 3.6 2.2 2.8 79 N 1 5 200 18 289 . . . . . . L567 19 01 30.2 [04 30 09 10.1 1.9 4.4 51 N 1 6 200 18 290 . . . . . . B133 (CB 180) 19 03 37.9 [06 59 05 10.7 4.4 6.9 [43 Y 1 6 200 18 291 . . . . . . L581 19 04 55.5 [03 59 32 19.6 13.9 16.5 34 N 1 6 200 18 292 . . . . . . L709 19 11 37.3 16 22 01 1.9 1.9 1.9 0 N 4 6 300 18 293 . . . . . . DC 13[205 19 13 12.4 [36 42 20 4.6 2.2 3.2 [76 N 3 A 130 20 294 . . . . . . L763 19 16 45.9 23 21 45 7.6 1.1 2.9 11 N 4 6 250 21 295 . . . . . . L730-1 19 17 40.5 19 51 09 6.8 1.7 3.4 25 N 2 5 160 22 296 . . . . . . L655 19 17 47.2 08 23 33 3.2 1.2 2.0 [26 N 4 5 200 18 297 . . . . . . L673-1 19 17 54.7 11 30 36 2.1 1.7 1.9 [32 Y 3 6 300 23 298 . . . . . . L730-2 19 18 12.4 19 56 53 2.8 1.1 1.8 66 N 2 5 160 22 299 . . . . . . L673-12 19 18 39.2 10 48 15 . . . . . . 7.6 . . . Y 3 6 300 23 300 . . . . . . L771 19 18 46.3 23 25 13 2.8 1.4 2.0 51 Y 4 6 400 18 301 . . . . . . L673-4 19 18 47.1 11 20 11 3.8 0.8 1.7 55 N 3 6 300 23 302 . . . . . . L673-5 19 18 53.6 11 27 16 2.7 1.1 1.7 [35 N 3 6 300 23 303 . . . . . . L673-13 19 19 00.9 10 46 45 . . . . . . 7.6 . . . Y 3 6 300 23 304 . . . . . . L673-14 19 19 01.9 10 51 27 . . . . . . 7.6 . . . Y 3 6 300 23 305 . . . . . . L673-6 19 19 06.2 11 30 39 1.6 0.8 1.1 47 N 3 6 300 23 306 . . . . . . L673-7 19 19 14.3 11 15 30 . . . . . . 7.0 . . . N 4 6 300 23 307 . . . . . . L673-8 19 19 15.4 11 12 20 . . . . . . 7.0 . . . N 4 6 300 23 308 . . . . . . L684 19 19 16.1 12 23 25 10.4 5.2 7.4 20 N 2 5 300 18 309 . . . . . . L673-9 19 19 21.1 11 10 54 . . . . . . 7.0 . . . N 4 6 300 23 310 . . . . . . L673-10 19 19 32.5 11 14 21 2.2 0.9 1.4 60 N 4 6 300 23 311 . . . . . . L677-1 19 19 50.0 11 27 19 1.6 0.8 1.1 83 N 3 6 300 23 312 . . . . . . L677-2 19 19 52.8 11 30 46 3.1 0.6 1.4 [37 N 3 6 300 23 313 . . . . . . L677-3 19 20 07.5 11 15 30 3.6 1.3 2.2 74 N 3 6 300 23 314 . . . . . . L677-4 19 20 22.8 11 16 57 1.7 0.8 1.2 83 N 3 6 300 23 315 . . . . . . L774-1 19 20 44.9 23 19 21 2.5 1.9 2.2 25 N 4 5 200 7 316 . . . . . . L774-2 19 21 34.2 23 17 18 1.0 1.0 1.0 0 N 4 5 200 7 317 . . . . . . L769-1 19 21 44.8 23 01 48 . . . . . . 9.4 . . . Y 4 6 200 7 318 . . . . . . L769-2 19 21 50.4 22 53 23 . . . . . . 6.8 . . . Y 4 6 200 7 319 . . . . . . L769-3 19 22 21.0 23 02 00 . . . . . . 5.4 . . . Y 4 6 200 7 320 . . . . . . L769-4 19 22 47.0 22 56 36 . . . . . . 6.2 . . . N 4 6 200 7 321 . . . . . . L698 19 23 37.5 12 59 48 11.0 1.1 3.5 [2 N 3 6 300 18 322 . . . . . . L778-1 19 24 19.8 23 53 04 19.6 0.9 4.2 [48 Y 4 6 200 7 323 . . . . . . L778-2 19 25 22.0 23 39 45 19.6 0.9 4.2 [48 N 4 6 200 7 324 . . . . . . L778-3 19 25 54.8 23 37 14 19.6 0.9 4.2 [48 N 4 6 200 7 325 . . . . . . L778-4 19 26 02.6 23 51 12 1.3 1.3 1.3 0 N 4 6 200 7 326 . . . . . . B335 19 34 35.6 07 27 34 3.2 2.1 2.6 14 Y 4 . . . 250 24 327 . . . . . . L694-1 19 38 06.5 10 43 33 8.2 2.5 4.5 82 N 4 6 . . . . . . 328 . . . . . . L694-2 19 38 42.4 10 49 59 . . . . . . 6.4 . . . N 4 6 . . . . . . 329 . . . . . . L694-3 19 38 54.0 10 43 42 2.4 1.7 2.0 [12 N 4 6 . . . . . . 242 TABLE 2ÈContinued a b R PA Distance Number Source R.A. (1950) Decl. (1950) (arcmin) (arcmin) (arcmin) (deg) EYSO DC Class (pc) References (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) 330 . . . . . . L758 19 44 12.8 18 54 47 1.6 0.9 1.2 51 N 4 5 400 18 331 . . . . . . L880 20 11 49.4 40 03 59 7.4 5.7 6.5 [35 N 4 5 700 18 332 . . . . . . L1152 20 35 26.0 67 43 23 1.6 0.6 1.0 57 Y 1 5 325 25 333 . . . . . . L1041-1 20 36 05.5 57 33 36 1.7 0.9 1.2 32 Y 1 5 440 23 334 . . . . . . L1041-2 20 36 05.9 57 38 48 1.8 0.8 1.2 30 N 1 5 440 23 335 . . . . . . L922-1 20 36 46.5 44 21 24 . . . . . . 2.6 . . . N 4 6 700 18 336 . . . . . . L922-2 20 37 04.6 44 25 20 . . . . . . 1.8 . . . N 4 6 700 18 337 . . . . . . L917 20 38 16.6 43 58 37 3.2 0.9 1.7 44 N 3 6 . . . . . . 338 . . . . . . L918 20 39 02.5 43 54 57 4.9 1.7 2.9 64 N 3 6 . . . . . . 339 . . . . . . L1049-1 20 39 50.8 57 16 45 3.0 1.4 2.0 50 N 2 6 440 23 340 . . . . . . L1147 20 39 58.4 67 09 36 6.5 1.3 2.9 44 N 2 3 325 25 341 . . . . . . L1049-2 20 40 16.8 57 22 57 1.9 0.8 1.2 9 N 3 4 440 23 342 . . . . . . L896-2 20 40 26.3 39 36 01 . . . . . . 3.0 . . . N 4 5 . . . . . . 343 . . . . . . L896-1 20 40 28.8 39 42 22 7.4 4.0 5.4 62 N 4 5 . . . . . . 344 . . . . . . L1148 20 40 38.7 67 09 48 7.1 1.6 3.4 46 N 2 6 325 25 345 . . . . . . L1155C 20 43 00.0 67 41 47 4.6 3.2 3.8 55 N 2 6 325 25 346 . . . . . . L1155D 20 43 17.9 67 26 12 4.9 1.4 2.6 43 N 1 6 325 25 347 . . . . . . L915 20 43 23.0 42 58 52 6.1 3.0 4.3 33 N 4 6 . . . . . . 348 . . . . . . L1155E 20 43 46.3 67 31 02 2.8 1.4 2.0 32 N 1 6 325 25 349 . . . . . . L1082C-3 20 47 59.4 60 00 36 4.4 0.6 1.6 47 N 3 5 440 26 350 . . . . . . L1082C-2 20 48 38.9 60 04 25 2.2 0.6 1.1 49 N 3 5 440 26 351 . . . . . . L1082C-1 20 50 20.0 60 07 13 2.5 1.7 2.1 43 Y 2 5 440 26 352 . . . . . . L1082B 20 52 40.7 59 59 59 . . . . . . 8.2 . . . Y 3 5 440 26 353 . . . . . . L981-1 20 58 36.3 50 08 19 . . . . . . 8.2 . . . N 3 6 700 27 354 . . . . . . L981-2 20 58 38.0 50 05 09 . . . . . . 8.2 . . . N 3 6 700 27 355 . . . . . . L971-1 20 59 08.1 49 17 21 2.4 1.1 1.6 24 N 2 5 700 27 356 . . . . . . L971-2 20 59 15.8 49 07 34 3.0 1.4 2.0 [3 N 2 5 700 27 357 . . . . . . L981-3 20 59 22.3 50 09 41 . . . . . . 8.2 . . . Y 3 6 700 27 358 . . . . . . L1174 20 59 22.7 68 01 12 4.7 2.2 3.2 63 Y 2 4 288 25 359 . . . . . . L1172A-2 21 01 10.8 67 34 34 5.1 3.5 4.2 12 N 1 6 288 25 360 . . . . . . L1172A-1 21 01 39.6 67 41 59 1.9 1.1 1.4 [34 Y 1 6 288 25 361 . . . . . . L1172A-3 21 03 22.6 67 29 06 2.5 1.3 1.8 1 N 1 6 288 25 362 . . . . . . L1063 21 06 44.6 56 06 09 4.4 1.7 2.7 50 N 3 5 800 18 363 . . . . . . B361-1 21 10 41.7 47 12 05 11.1 11.1 11.1 0 Y 3 . . . 350 28 364 . . . . . . B361-2 21 10 53.2 47 07 23 11.1 11.1 11.1 0 Y 3 . . . 350 28 365 . . . . . . L1125-1 21 13 07.8 61 32 26 3.2 1.5 2.2 72 N 2 5 300 1 366 . . . . . . L1125-2 21 14 07.0 61 27 10 . . . . . . 4.8 . . . Y 2 5 300 1 367 . . . . . . L944-1 21 14 42.6 42 59 47 3.0 0.8 1.5 [49 N 4 6 . . . . . . 368 . . . . . . L944-2 21 15 54.0 43 05 41 . . . . . . 2.8 . . . N 4 6 . . . . . . 369 . . . . . . L944-3 21 16 59.7 43 12 57 0.9 0.6 0.7 27 N 4 6 . . . . . . 370 . . . . . . L952-1 21 18 08.5 43 18 07 2.0 0.7 1.2 44 N 4 5 . . . . . . 371 . . . . . . L952-2 21 18 25.0 43 19 59 3.2 0.8 1.6 64 N 4 5 . . . . . . 372 . . . . . . L953 21 19 31.8 43 08 46 0.9 0.5 0.7 [19 N 4 6 . . . . . . 373 . . . . . . L1021 21 20 34.8 50 50 17 0.7 0.6 0.6 0 N 4 6 200 29 374 . . . . . . L1014-1 21 22 20.6 49 56 52 7.0 3.2 4.7 67 N 4 6 200 29 375 . . . . . . L1014-2 21 22 22.2 49 46 10 2.4 1.1 1.6 [58 N 3 6 200 29 376 . . . . . . L1099-1 21 34 27.9 57 13 18 1.7 0.8 1.2 81 N 4 5 . . . . . . 377 . . . . . . L973 21 35 16.3 43 06 57 2.2 0.9 1.4 [8 Y 3 5 . . . . . . 378 . . . . . . L1111 21 38 53.6 57 34 24 3.7 2.4 3.0 [42 N 4 6 150 29 379 . . . . . . L1121 21 39 10.0 58 02 33 2.4 1.7 2.0 25 Y 4 5 . . . . . . 380 . . . . . . L1103-1 21 39 49.8 56 23 32 4.4 2.4 3.2 54 N 4 6 . . . . . . 381 . . . . . . L1103-2 21 40 41.0 56 30 07 2.1 1.0 1.4 21 N 4 6 150 29 382 . . . . . . L1113-2 21 42 45.4 56 57 33 2.4 1.6 2.0 64 N 4 5 150 29 383 . . . . . . L1113-1 21 42 56.7 56 56 25 0.9 0.9 0.9 0 N 4 5 150 29 384 . . . . . . L1031C 21 44 35.9 47 03 42 7.3 2.8 4.5 [87 Y 3 5 900 30 385 . . . . . . L1139-1 21 53 14.7 58 20 59 2.1 0.9 1.4 [48 N 2 5 . . . . . . 386 . . . . . . L1139-2 21 53 47.3 58 20 14 4.6 1.1 2.2 55 Y 2 5 . . . . . . 387 . . . . . . L1143 21 57 03.0 58 42 25 7.3 2.1 3.9 46 Y 4 6 . . . . . . 388 . . . . . . L1166 22 03 46.7 59 19 07 1.9 0.9 1.3 59 N 4 6 . . . . . . 389 . . . . . . L1164 22 05 07.7 58 51 15 . . . . . . 7.4 . . . Y 4 6 . . . . . . 390 . . . . . . L1235 22 14 44.4 73 08 05 6.3 3.5 4.7 67 N 2 6 200 3 391 . . . . . . L1195 22 25 18.1 61 01 06 4.6 1.9 3.0 13 N 2 5 . . . . . . 392 . . . . . . L1221 22 26 38.4 68 45 48 6.2 2.4 3.9 43 Y 2 5 200 23 393 . . . . . . L1251A-2 22 26 46.5 74 58 10 3.3 2.2 2.7 54 N 3 5 300 31 394 . . . . . . L1185 22 27 27.6 58 53 30 4.1 1.6 2.6 75 N 3 6 . . . . . . 395 . . . . . . L1251A-1 22 30 00.8 74 57 04 8.2 5.1 6.5 [67 Y 2 5 300 31 243 200 400 600 800 1000 5000 5500 6000 6500 7000 0 1 2 3 4 5 0 0.2 0.4 Lynds 5 0 0.2 0.4 Lynds 6 0 0.2 0.4 Hartley A 244 LEE & MYERS TABLE 2ÈContinued a b R PA Distance Number Source R.A. (1950) Decl. (1950) (arcmin) (arcmin) (arcmin) (deg) EYSO DC Class (pc) References (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) 396 . . . . . . L1197 22 35 08.0 58 41 46 4.3 1.2 2.3 [56 N 4 6 . . . . . . 397 . . . . . . L1251 22 36 26.0 74 54 46 7.1 1.9 3.7 52 N 1 5 300 31 398 . . . . . . L1229 23 12 16.8 61 46 47 3.8 1.4 2.3 24 N 4 5 . . . . . . 399 . . . . . . L1234 23 15 47.5 62 10 15 1.9 0.8 1.2 [73 N 4 6 . . . . . . 400 . . . . . . CB 243 (L1246) 23 23 07.2 63 19 48 3.3 1.1 1.9 [73 Y 4 6 . . . . . . 401 . . . . . . L1262A (CB 244) 23 23 47.7 74 01 29 4.7 2.1 3.1 [73 Y 2 6 200 3 402 . . . . . . CB 246 (L1253) 23 54 10.8 58 17 29 3.2 2.1 2.6 [48 N 3 6 140 3 403 . . . . . . L1263 23 54 54.2 64 32 27 2.5 1.3 1.8 [10 N 1 5 . . . . . . 404 . . . . . . L1271-1 23 57 32.6 67 05 07 11.4 1.1 3.5 55 N 4 5 . . . . . . 405 . . . . . . L1271-2 23 58 20.7 66 52 29 2.1 1.1 1.5 31 Y 4 5 . . . . . . 406 . . . . . . L1271-3 23 59 15.3 67 01 48 2.8 2.2 2.5 [51 N 4 5 . . . . . . NOTES.ÈThese 406 sources are positions showing local intensity minima in the STScI Digitized Sky Survey (DSS). Cols. (1)È(4) : Sequential numbers, source names, and their coordinates. Cols. (5) and (6) : a and b are sizes of major and minor axis of FWHM of selected cores, respectively. Col. (7) : Geometric mean (ab)0.5 for the cores whose a and b are measured, or the equivalent diameter 2](A/n)0.5 for the cores in which a and b are not measured owing to its irregularity. Col. (8) : Position angle of the core. Col. (9) : N, starless cores ; Y, cores with embedded YSOs; PM, cores with preÈmain-sequence (PMS) stars ; and PM*, PMSs that are determined by optical spectroscopy (Herbig & Bell 1988). Col. (10) : Darkness contrast of the opaque core to the background, where 1 corresponds to the least dark and 4 to the most dark. Col. (11) : Lynds opacity class and Hartley A class. Col. (12) : Distances to the cores. Col. (13) : References for core distances. REFERENCES.È(1) Lindblad et al. 1973, Lindblad ring ; (2) Herbig & Jones 1983, Per OB2; (3) Snell 1981; (4) Elias 1978b, Taurus; (5) Maddalena et al. 1986, Orion A, B; (6) Murdin & Penston 1977; (7) Goodman et al. 1993; (8) Bok & McCarthy 1974; (9) Carballo & Sahu 1994; (10) Harjunpaa, Lijiestrom, & Mattila 1991, Vela; (11) Schwartz 1991, Cha I ; (12) Rogers 1960, Coal Sack; (13) Hetem et al. 1988, Musca; (14) Gauvin & Strom 1992, Cha II, III ; (15) Neckel & Klare 1980, G317-4; (16) Murphy 1985, Lupus; (17) Chini 1981, Ophiuchus; (18) Dame & Thaddeus 1985, Aquila Rift (200 pc), Cloud B (300 pc), Cloud C (500 pc), Vul Rift (400 pc), Cyg Rift (700 pc), Cyg OB7 (800 pc) ; (19) Beichman et al. 1986; (20) Marraco & Rydgren 1981; (21) Cohen & Kuhi 1979; (22) Frerking & Langer 1982; (23) Felli, Palagi, & Tofani 1992; (24) Tomita, Saito, & Ohtani 1979; (25) Straizys et al. 1992; (26) Viotti 1969; (27) Clark 1986; (28) Schmidt 1975; (29) Leung, Kutner, &Mead 1982; (30) Elias 1978a; (31) Kun & Prusti 1993; (32) Graham & Frogel 1985, Norma. 4@ with a mean (^s.e.m.) of 3.@7(^0.1). This distribution is similar to that found by previous study of CB. The size distribution of starless cores, which comprise a majority, resembles the size distribution of all cores, while the size of cores with EYSOs is uniformly distributed between 1@ and 8@. The interesting thing is that the mean size (5.@1^0.@4) of the cores with EYSOs is larger than that (3.@3^0.@1) of starless cores. We also Ðnd a corresponding di†erence in the distribution of the linear sizes, as illustrated in Figure 5. Distances (Table 2, col. [12]) of cores for determination of the linear sizes have been obtained from numerous papers (see refer- FIG. 2.ÈExample of a cut-proÐle of L1622 cloud. This cut-proÐle was obtained by crossing two intensity minima of L1622A and L1622B. The angular size for 1 pixel in the abscissa is about 0A.6. The data value (DN) is on a scale of photographic density (c) in the expression of c\DN/6553.4 (Postman 1996). The data values (IB and IC) of DSS for the background and the core are approximately adopted from this proÐle. ences listed in Table 2) referred to by Dame et al. (1987), BM, Vilas-Boas et al. (1994), Hilton & Lahulla (1995), and Chen et al. (1997). We adopted the distances given by those papers if our sources are in a vicinity (within 1¡) of the FIG. 3.ÈRelation of the darkness contrast (DC) to Lynds class 5 and 6 and HMSTG class A. Lynds 6 and HMSTG A clouds more likely have a DC of 3 or 4 than Lynds 5 clouds. TABLE 3 IRAS POINT SOURCES AND PMS STARS ASSOCIATED WITH OPTICALLY SELECTED CORES F12km F25km F60km F100km Core Name IRAS or PMSa Name R.A. (1950) Decl. (1950) (Jy) (Jy) (Jy) (Jy) L1358-1 . . . . . . . . . . . . . . . . . . 02514]6902 02 51 24.0 69 02 36 0.76 0.25L 0.40L 6.61 CB 17 . . . . . . . . . . . . . . . . . . . . 04005]5647 04 00 30.8 56 47 59 0.44L 0.25L 0.90 5.81 L1495-3 . . . . . . . . . . . . . . . . . . 04154]2823 04 15 25.7 28 23 56 0.45 1.02 1.96 7.80L L1506A . . . . . . . . . . . . . . . . . . 04207]2449 04 20 39.0 24 49 24 0.46 0.65 0.86 1.92 B217-1 . . . . . . . . . . . . . . . . . . . 04249]2612 04 24 53.2 26 12 39 0.36L 1.33 4.61 9.29 L1524-2 . . . . . . . . . . . . . . . . . . 04264]2426 04 26 21.7 24 26 26 14.86 38.73 59.70 47.42 L1524-1 . . . . . . . . . . . . . . . . . . 04265]2433 04 26 28.0 24 33 23 0.44 2.91 5.40 9.12L L1524-3 . . . . . . . . . . . . . . . . . . 04264]2426 04 26 21.7 24 26 26 14.86 38.73 59.70 47.42 TMC 2-2 . . . . . . . . . . . . . . . . . 04288]2417 04 28 48.7 24 17 54 0.33 1.03 2.56 5.70 TMC 2A . . . . . . . . . . . . . . . . . 04292]2422 04 29 13.2 24 22 39 1.06 3.98 7.18 9.82 TMC 2-1 . . . . . . . . . . . . . . . . . 04292]2422 04 29 13.2 24 22 39 1.06 3.98 7.18 9.82 B18-4 . . . . . . . . . . . . . . . . . . . . . 04325]2402 04 32 31.6 24 02 08 0.25L 2.11 12.82 22.28 L1527A-1 . . . . . . . . . . . . . . . . 04354]2604 04 35 23.9 26 04 51 1.91 3.87 5.92 6.49 L1534 . . . . . . . . . . . . . . . . . . . . 04363]2539 04 36 16.2 25 39 07 0.55 0.72 0.40L 2.01L L1534 . . . . . . . . . . . . . . . . . . . . 04365]2535 04 36 31.0 25 35 52 1.19 8.63 35.97 39.08 L1534 . . . . . . . . . . . . . . . . . . . . 04369]2539 04 36 54.6 25 39 17 5.01 6.79 7.24 18.20 TMC 1-1 . . . . . . . . . . . . . . . . . 04381]2540 04 38 07.6 25 40 48 0.44 2.68 10.28 13.93 TMC 1C . . . . . . . . . . . . . . . . . 04386]2550 04 38 34.2 25 50 43 0.54 1.54 2.88 8.02L B25A . . . . . . . . . . . . . . . . . . . . . 05418]0907 05 41 45.3 09 07 40 0.28 2.91 25.59 74.47 L1622B . . . . . . . . . . . . . . . . . . . 05523]0146 05 52 17.2 01 46 41 0.34L 0.31 1.45 31.33 L1645 . . . . . . . . . . . . . . . . . . . . 06053[0533 06 05 16.3 [05 33 49 0.25L 0.60 13.06 22.28 L1578-1, L1578-2 . . . . . . . Bretz 34 06 05 42.5 18 08 21 . . . . . . . . . . . . V14 . . . . . . . . . . . . . . . . . . . . . . . 08077[35561 08 07 40.2 [35 56 07 0.63 3.73 18.20 47.42 DC 2573[25-1 . . . . . . . . . 08153[3945 08 15 16.6 [39 45 44 0.41 1.24 1.47 17.70L DC 2660[75-2 . . . . . . . . . 08196[4931 08 19 37.1 [49 31 13 0.25L 7.05 53.46 74.47L DC 2674[75 . . . . . . . . . . . . 08243[5050 08 24 16.5 [50 50 44 0.82 6.31 26.06 58.08 DC 2672[72 . . . . . . . . . . . . 08251[5030 08 25 03.4 [50 30 34 0.25L 0.25L 1.19 17.06 DC 2977[28 . . . . . . . . . . . . 11591[64521 11 59 03.1 [64 52 11 0.25L 6.55 77.27 192.31 Ch 7 . . . . . . . . . . . . . . . . . . . . . . 12496[7650 12 49 38.0 [76 50 45 39.45 85.51 104.71 87.10 Ch 7 . . . . . . . . . . . . . . . . . . . . . . 12501[7658 12 50 03.0 [76 58 49 0.25L 1.02 2.70 5.35L Ch 19-1 . . . . . . . . . . . . . . . . . . 12571[7654 12 57 07.6 [76 54 31 0.31L 0.52 0.86 5.81 DC 3038[142 . . . . . . . . . . 13037[76442 13 03 41.4 [76 44 03 0.25L 1.05 6.37 22.49 DC 3148[51 . . . . . . . . . . . . 14451[6502 14 45 07.6 [65 02 55 1.26 1.46 4.66 22.70 DC 3379]164 . . . . . . . . . . 15363[3436 15 36 15.2 [34 36 32 0.56 0.82 0.40L 13.30L DC 3388]165-4 . . . . . . . . 15390[3400 15 39 01.6 [34 00 32 0.25L 0.29L 0.76 6.73 DC 3388]165-4,5 . . . . . . 15399[33592 15 39 51.2 [33 59 36 0.25L 1.28 15.28 41.30 DC 3392]161-1 . . . . . . . . 15420[3408 15 42 01.3 [34 08 09 2.58 3.98 7.94 24.43 DC 3390]150 . . . . . . . . . . 15449[3506 15 44 51.6 [35 06 36 0.91 1.98 1.96 12.47L DC 3386]119-2 . . . . . . . . 15534[3740 15 53 24.5 [37 40 34 2.44 4.53 4.97 10.47L DC 3397]92-1 . . . . . . . . . 16054[3857 16 05 25.6 [38 57 50 0.60L 0.72 6.08 63.68 DC 3397]92-1 . . . . . . . . . 16059[3850 16 05 56.2 [38 50 28 0.26L 0.27L 1.18 8.24 DC 3397]92-1 . . . . . . . . . 16065[3903 16 06 27.6 [39 03 30 0.38 0.54 0.61 24.66L DC 3397]92-1,2,3 . . . . . . 16073[3900 16 07 17.0 [39 00 24 0.25L 0.28L 0.84 11.69 DC 3397]92-2 . . . . . . . . . 16059[3850 16 05 56.2 [38 50 28 0.26L 0.27L 1.18 8.24 DC 3397]92-2,3 . . . . . . . . 16065[3903 16 06 27.6 [39 03 30 0.38 0.54 0.61 24.66L DC 3402]90-1,2,3 . . . . . . 16082[38523 16 08 12.7 [38 52 25 4.92 3.44 0.90 5.01L L1681A . . . . . . . . . . . . . . . . . . 16226[2417 16 22 36.0 [24 17 56 4.02 10.28 2.56L 26.55L L1681A . . . . . . . . . . . . . . . . . . 16226[2408 16 22 38.7 [24 08 52 2.21 3.05 25.12L 794.33L L1681A . . . . . . . . . . . . . . . . . . 16228[2418 16 22 47.9 [24 18 48 1.91 3.05 2.94L 29.92L L1681A . . . . . . . . . . . . . . . . . . 16232[2427 16 23 09.6 [24 27 35 3.47L 52.48 469.89L 1018.59 L1681A . . . . . . . . . . . . . . . . . . 16234[2409 16 23 22.7 [24 09 30 3.44 3.80 2.81L 24.21L L1681A . . . . . . . . . . . . . . . . . . 16234[2436 16 23 25.0 [24 36 58 0.91 1.49 8.24 28.31L L1681A . . . . . . . . . . . . . . . . . . 16235[2416 16 23 31.5 [24 16 56 34.99 265.46 2187.76 4655.86 L1681A . . . . . . . . . . . . . . . . . . 16237[2428 16 23 44.2 [24 28 07 2.88 7.80 148.59L 299.23 L1681A . . . . . . . . . . . . . . . . . . 16239[2428 16 23 53.5 [24 28 12 4.45 19.05 197.70L 787.05L L1681A . . . . . . . . . . . . . . . . . . 16239[2438 16 23 56.6 [24 38 52 3.56 6.92 8.47 39.81L L1681A . . . . . . . . . . . . . . . . . . 16241[2430 16 24 03.6 [24 30 43 39.45 73.79 197.70 586.14 L1681A . . . . . . . . . . . . . . . . . . 16243[2422 16 24 15.7 [24 22 06 2.09L 6.55 64.27L 218.78 L1681A . . . . . . . . . . . . . . . . . . 16244[24321 16 24 26.2 [24 32 53 9.91 67.30 111.69L 349.95 L1681A . . . . . . . . . . . . . . . . . . 16246[2423 16 24 34.7 [24 23 51 7.80 46.56 65.46L 224.91L L1681A . . . . . . . . . . . . . . . . . . 16246[2415 16 24 38.1 [24 15 22 0.93 1.51 6.43L 165.96L L1681A . . . . . . . . . . . . . . . . . . 16246[2436 16 24 38.6 [24 36 36 1.63 2.94 4.57 31.05L L1681A . . . . . . . . . . . . . . . . . . 16248[2424 16 24 47.7 [24 24 59 5.70 17.22 65.46L 35.65 L1681A . . . . . . . . . . . . . . . . . . 16253[2429 16 25 20.4 [24 29 55 0.25L 0.42L 2.91 16.29 L1681A . . . . . . . . . . . . . . . . . . 16257[2421 16 25 43.4 [24 21 50 0.67 0.73 2.07 52.48L TABLE 3ÈContinued F12km F25km F60km F100km Core Name IRAS or PMSa Name R.A. (1950) Decl. (1950) (Jy) (Jy) (Jy) (Jy) L1696B-1 . . . . . . . . . . . . . . . . 16242[2412 16 24 10.2 [24 12 34 2.27 19.77 33.73 165.96L L1696B-1 . . . . . . . . . . . . . . . . 16246[2415 16 24 38.1 [24 15 22 0.93 1.51 6.43L 165.96L L1696B-1 . . . . . . . . . . . . . . . . 16257[2421 16 25 43.4 [24 21 50 0.67 0.73 2.07 52.48L L1709B-1 . . . . . . . . . . . . . . . . 16286[2355 16 28 34.7 [23 55 13 1.19 3.73 9.46 60.81L L1709B-1 . . . . . . . . . . . . . . . . 16294[2358 16 29 21.3 [23 58 57 0.25L 0.71L 1.18 15.56 L1689B2 . . . . . . . . . . . . . . . . . 16293[24221 16 29 20.9 [24 22 13 0.25L 1.82 255.86 1028.02 L1689B4, L1689B1 . . . . . . 16306[2425 16 30 33.2 [24 25 21 0.37L 0.39L 1.49 31.05 DC 3387]18 . . . . . . . . . . . . 16307[4455 16 30 39.9 [44 55 13 1.69L 0.62 2.81 38.73L L1689B5 . . . . . . . . . . . . . . . . . 16306[2425 16 30 33.2 [24 25 21 0.37L 0.39L 1.49 31.05 L1689B5 . . . . . . . . . . . . . . . . . 16314[2439 16 31 23.9 [24 39 17 0.25L 0.47L 1.11 15.00 L43D . . . . . . . . . . . . . . . . . . . . . 16316[1540 16 31 37.7 [15 40 52 1.50 6.03 35.32 64.27 L1689B1 . . . . . . . . . . . . . . . . . 16314[2439 16 31 23.9 [24 39 17 0.25L 0.47L 1.11 15.00 L43E . . . . . . . . . . . . . . . . . . . . . 16316[1540 16 31 37.7 [15 40 52 1.50 6.03 35.32 64.27 L260 . . . . . . . . . . . . . . . . . . . . . . 16442[0930 16 44 14.2 [09 30 03 0.57 3.31 7.80 7.52 L255-1 . . . . . . . . . . . . . . . . . . . . 16451[0953 16 45 07.0 [09 53 20 0.25L 0.32L 0.60 12.82 L234E2 . . . . . . . . . . . . . . . . . . . 16452[1046 16 45 10.0 [10 45 53 0.25L 0.34L 0.99 7.11 L158-3 . . . . . . . . . . . . . . . . . . . . 16455[1405 16 45 32.0 [14 05 31 0.63 0.90 1.22 13.30L L158-4 . . . . . . . . . . . . . . . . . . . . 16464[1407 16 46 25.2 [14 07 48 0.60L 0.36L 0.63 6.49 L162-1 . . . . . . . . . . . . . . . . . . . . 16459[1411 16 45 54.7 [14 11 20 1.41 1.91 2.33L 6.49 L162-1 . . . . . . . . . . . . . . . . . . . . 16464[1407 16 46 25.2 [14 07 48 0.60L 0.36L 0.63 6.49 CB 68-3 . . . . . . . . . . . . . . . . . . 16534[1557 16 53 24.6 [15 57 27 0.39 1.41 1.94 12.13L CB 68-1 . . . . . . . . . . . . . . . . . . 16545[1604 16 54 27.2 [16 04 48 0.25L 1.49 19.41 33.73 L100 . . . . . . . . . . . . . . . . . . . . . . 17131[2053 17 13 03.9 [20 53 39 0.38L 1.22L 4.13 14.59 L100 . . . . . . . . . . . . . . . . . . . . . . 17134[20563 17 13 22.4 [20 56 13 8.95 5.60 0.95 16.75L L1774 . . . . . . . . . . . . . . . . . . . . . 17194[2705 17 19 22.9 [27 05 56 0.72L 6.19 6.73 10.86L DC 3463-41 . . . . . . . . . . . . . . 17229[42373 17 22 53.4 [42 37 19 1.47 0.79 1.53 17.06 L425 . . . . . . . . . . . . . . . . . . . . . . 17442[0433 17 44 11.7 [04 33 31 0.41 2.31 8.17 9.64 L323(CB 125) . . . . . . . . . . . . 18122[1818 18 12 14.2 [18 18 30 3.91 12.13 58.08L 625.17L L483-1 . . . . . . . . . . . . . . . . . . . . 18148[04401 18 14 50.6 [04 40 49 0.25L 6.92 88.72 165.96 L406 . . . . . . . . . . . . . . . . . . . . . . 18231[1144 18 23 04.5 [11 44 50 7.38 10.67 21.68L 440.55L L406 . . . . . . . . . . . . . . . . . . . . . . 18233[1154 18 23 15.2 [11 54 22 15.14 88.72 937.56 2857.59 B133 . . . . . . . . . . . . . . . . . . . . . . 19038[0659 19 03 48.0 [06 59 47 0.25L 0.50 0.98 9.82 L673-1 . . . . . . . . . . . . . . . . . . . . 19179]1129 19 17 54.0 11 29 56 0.27L 1.06 3.94 18.54 L673-12 . . . . . . . . . . . . . . . . . . 19184]1055 19 18 24.2 10 55 15 3.73 5.45 3.70L 9.73 L673-12 . . . . . . . . . . . . . . . . . . 19190]1048 19 19 00.4 10 48 12 1.13 3.40 7.80 61.38L L771 . . . . . . . . . . . . . . . . . . . . . . 19187]2325 19 18 39.8 23 25 50 0.25L 0.25L 1.04 6.61 L673-13 . . . . . . . . . . . . . . . . . . 19190]1048 19 19 00.4 10 48 12 1.13 3.40 7.80 61.38L L673-14 . . . . . . . . . . . . . . . . . . 19190]1048 19 19 00.4 10 48 12 1.13 3.40 7.80 61.38L L774-1, L769-1 . . . . . . . . . . 19216]2302 19 21 35.9 23 02 54 0.51L 0.26 1.13 7.38L L774-1 . . . . . . . . . . . . . . . . . . . . 19219]2300 19 21 54.1 23 00 46 0.25L 0.25L 2.78 12.47 L774-1 . . . . . . . . . . . . . . . . . . . . 19221]2300 19 22 08.3 23 00 05 0.54 1.22 1.57 5.81L L769-2 . . . . . . . . . . . . . . . . . . . . 19221]2300 19 22 08.3 23 00 05 0.54 1.22 1.57 5.81L L769-3 . . . . . . . . . . . . . . . . . . . . 19221]2300 19 22 08.3 23 00 05 0.54 1.22 1.57 5.81L L778-1 . . . . . . . . . . . . . . . . . . . . 19244]2352 19 24 23.8 23 52 10 0.33L 0.25L 3.05 8.63 L778-1 . . . . . . . . . . . . . . . . . . . . 19244]2350 19 24 23.9 23 50 56 0.33 0.57 0.40L 9.12 B335 . . . . . . . . . . . . . . . . . . . . . . 19346]07271 19 34 35.3 07 27 24 0.25L 0.25L 8.32 42.07 L1152 . . . . . . . . . . . . . . . . . . . . . 20353]6742 20 35 20.1 67 42 30 0.25L 0.34 4.09 7.11 L1041-1 . . . . . . . . . . . . . . . . . . 20361]5733 20 36 08.7 57 33 40 0.25L 1.16 11.38 26.55 L1082C-1 . . . . . . . . . . . . . . . . 20503]6006 20 50 19.6 60 06 41 0.25L 0.30 1.54 13.80L L1082B . . . . . . . . . . . . . . . . . . . 20521]6003 20 52 04.7 60 03 14 0.49 1.36 2.47 6.25 L1082B . . . . . . . . . . . . . . . . . . . 20527]5958 20 52 41.0 59 58 21 0.39L 0.25L 1.36 5.65 L981-3 . . . . . . . . . . . . . . . . . . . . 20595]5009 20 59 32.3 50 09 53 1.15 2.81 6.55 39.81L L1174 . . . . . . . . . . . . . . . . . . . . . 20597]6800 20 59 42.1 68 00 13 0.25L 0.82 4.49 54.95L L1172A-1 . . . . . . . . . . . . . . . . 21017]6742 21 01 44.2 67 42 24 0.28L 0.26 1.33 5.81 B361-1,2 . . . . . . . . . . . . . . . . . . 21107]4712 21 10 41.0 47 12 01 0.25L 0.78 15.70 39.08 L1125-2 . . . . . . . . . . . . . . . . . . 21137]6126 21 13 44.5 61 26 52 0.26 0.53 3.66 23.77 L1014-1 . . . . . . . . . . . . . . . . . . 21221]4955 21 22 08.7 49 55 09 0.42L 0.19 0.69L 8.71 L973 . . . . . . . . . . . . . . . . . . . . . . 21352]4307 21 35 14.4 43 07 05 1.02 3.56 6.85 13.93 L1121 . . . . . . . . . . . . . . . . . . . . . 21392]5802 21 39 10.3 58 02 29 0.56 8.87 144.54 424.62 L1031C . . . . . . . . . . . . . . . . . . . 21446]4704 21 44 35.6 47 04 21 0.25L 0.34L 0.86 13.43 L1139-2 . . . . . . . . . . . . . . . . . . 21539]5821 21 53 55.2 58 21 25 0.25L 0.25L 5.70 28.84 L1143 . . . . . . . . . . . . . . . . . . . . . 21570]5842 21 56 58.8 58 42 46 0.51 1.64 4.45 4.74 L1164 . . . . . . . . . . . . . . . . . . . . . 22052]5848 22 05 09.8 58 48 06 0.25L 5.20 51.52 93.76 L1221 . . . . . . . . . . . . . . . . . . . . . 22266]6845 22 26 37.2 68 45 52 0.98 3.53 12.36 25.82 L1251A-1 . . . . . . . . . . . . . . . . 22291]7458 22 29 03.3 74 58 51 0.28L 0.38 0.73 9.12L CB 243 . . . . . . . . . . . . . . . . . . . 23229]6320 23 22 52.9 63 20 04 0.26 0.74 2.07 7.94 0 10 20 0 20 40 60 80 N=348 All Cores 0 20 40 60 80 N=275 Starless Cores 0 20 40 60 80 N=72 Cores with EYSOs 0 0.5 1 1.5 0 20 40 60 N=292 All Cores 0 20 40 60 N=229 Starless Cores 0 20 40 60 N=63 Cores with EYSOs OPTICALLY SELECTED CORES 247 TABLE 3ÈContinued F12km F25km F60km F100km Core Name IRAS or PMSa Name R.A. (1950) Decl. (1950) (Jy) (Jy) (Jy) (Jy) L1262A . . . . . . 23238]7401 23 23 48.8 74 01 08 0.25L 0.77 9.64 15.14 L1271-2 . . . . . . 23585]6653 23 58 30.1 66 53 53 1.54 2.25 40.55L 55.46L NOTE.ÈUnits of right ascension are hours, minutes, and seconds, and units of declination are degrees, arcminutes, and arcseconds. a Names with 1 and 2 added were previously known as class 0 YSOs by Bachiller 1996 and Mardones et al. 1997, respectively. Names with 3 and 4 added were identiÐed as PMS by the criteria of Weintraub 1990 and the PMS catalog of Herbig & Bell 1988, respectively clouds whose distances are known and/or LSR velocities [known from a recent CS (2È1) and N (1È0) survey; 2H` Lee, Myers, & Tafalla 1999] of our sources are within ^2 km s~1 of those of the known clouds. Linear sizes of more than 80% of all the cores are between 0.05 and 0.35 pc and the mean size (^s.e.m.) of the cores is about 0.24 (^0.01) pc. Most (about 70%) of the cores with EYSOs have sizes of 0.15È0.4 pc with a mean of 0.33 (^0.03) pc, while most (more than 85%) of starless cores have sizes of 0.05È0.35 pc with a mean of 0.21 (^0.01) pc. The sizes of cores with EYSOs clearly tend to be larger than those of starless cores. Interestingly, this tendency is similar to that of the distribution of the sizes of NH cores by BM. We investigated wh3ether this apparent di†erence in core sizes originates from any distance e†ect. Figure 6 shows the distribution of distances of starless cores and of cores with EYSOs, indicating no signiÐcant di†erence in the distances between these two groups. Moreover the mean distances are nearly same within the range of error, about 227^8 pc for starless cores and about 244^19 pc for cores with EYSOs. Thus it seems real that the cores with EYSOs are usually larger than starless cores by a typical factor of 1.6. FIG. 4.ÈDistribution of the apparent angular size of cores. The positions of mean angular sizes (mean^s.e.m.) of 3.@7^0@.1, 3.@3^0.@1, and 5.@1^0.@4 for all cores, starless cores, and cores with EYSOs, respectively, are marked with vertical bars in each panel. This may mean that larger cores have a greater likelihood to form stars since they have more initial mass, or alternatively cores with EYSOs may be larger because they have been growing for a longer time. The aspect ratio (a/b) of cores ranges mostly between 1.5 and 2.5 for both starless cores and cores with EYSOs (Fig. 7). The mean (^s.e.m.) aspect ratios are 2.4^0.1, 2.2^0.2, and 2.4^0.1 for starless cores, cores with YSOs, and all cores, respectively. The most elongated cores are L1271-1 (10.4) and L698 (10.0). Our measured aspect ratios are slightly larger than the value of CB (2.0) for their cores, the value of Wood et al. (1994) (1.98) for the IRAS cores, and the value of BM (1.9^0.12) for their 41 NH cores. Our measurement for the aspect ratio of cores co3nÐrms that most cores are more likely elongated than spherical. 2.2.3. Spatial Distribution of Selected Cores Figure 8 shows the spatial distribution of cores in galactic coordinates. This indicates that the cores have been uniformly selected from all regions. There seems to be no indication that the distribution of cores with EYSOs is di†erent from that of starless cores. In this Ðgure we marked Ðve distinctive star-forming regions in boxes that contain cores FIG. 5.ÈDistribution of the linear size of cores. The positions of mean linear sizes (mean^s.e.m.) of 0.24^0.01 pc, 0.22^0.01 pc, and 0.33^0.02 pc for all cores, starless cores, and cores with EYSOs, respectively, are marked with vertical bars in each panel. 0 200 400 600 800 1000 0 50 100 150 200 N=292 All Cores 0 50 100 150 200 N=229 Starless Cores 0 50 100 150 200 N=63 Cores with EYSOs 0 2 4 6 8 10 12 0 50 100 150 N=308 Total 0 50 100 150 N=249 Starless Cores 0 50 100 150 N=58 Cores with EYSOs 248 LEE & MYERS Vol. 123 FIG. 6.ÈDistance distribution of cores. The distributions of distances of starless cores and cores with EYSO are not di†erent. The positions of mean distance (mean^s.e.m.) of 231^8 pc, 227^8 pc, and 244^19 pc for all cores, starless cores, and cores with EYSOs, respectively, are indicated with vertical bars in each panel. with similar distances. They are Taurus (Ungerechts & Thaddeus 1987), Ophiuchus (de Geus, Bronfman, & Thaddeus 1990), Lupus (Murphy, Cohen, & May 1986), Chamaeleon II, III (Chen et al. 1997), and Vela (Vilas-Boas et al. 1994). The boundaries of each areas were adopted from the references listed above in parentheses. 2.2.4. Implications of the Ratio of the Number of Cores with EY SOs to the Number of Starless Cores Our sample gives a ratio [N(cores with EYSOs)]/ [N(starless cores)] of about 0.31 (B94/306). This ratio is important in constraining models of core formation, of FIG. 7.ÈDistribution of the aspect ratio for all cores, starless cores, and cores with EYSOs. The positions of the mean aspect ratio (mean^s.e.m.) of 2.4^0.1, 2.4^0.1, and 2.2^0.2 for all cores, starless cores, and cores with EYSOs, respectively, are indicated with vertical bars in each panel. which ambipolar di†usion is the best known (Mestel & Spitzer 1956). If every core undergoes ambipolar di†usion (i.e., dense core formation), infall, and then protostellar emission, the value of the ratio [N(cores with EYSOs)]/ [N(starless cores)] should be approximately [t(life of protostar)]/[t(core formation)], assuming that the cores have uncorrelated start times. The time t(life of protostar) will correspond approximately to the duration of the class 0]class I stages, based on our IRAS selection criteria described in ° 2.1. This time interval has been observationally determined to be about (1È5)]105 yr from the relative numbers of embedded objects and T Tauri stars FIG. 8.ÈDistributions in Galactic coordinates of (a) cores with EYSOs and (b) starless cores listed in Table 2 No. 1, 1999 OPTICALLY SELECTED CORES 249 (Myers et al. 1987; Wilking, Lada, & Young 1989; Kenyon et al. 1990). The time t(core formation) should be the time that the core is detectable at its typical observed density, according to its formation model. The cores in our catalog (most of which have been selected from Lynds classes 5 and 6) are thought to have visual extinctions of 4.5È6 mag in their centers (Cernicharo & Bachiller 1984). This means that the mean number density in the center of our optically selected cores is about (6È8)]103 cm~3, assuming a core diameter of 0.24 pc from our statistics and the relationship N(H cm~2 from Dickman (1978) where 2)B1]1021Av N(H and are column density of and magnitude of 2) Av Hvisual extinction, respectively. Therefor2e the time that the core has gas density (6È8)]103 cm~3 can be obtained from ambipolar di†usion models. We Ðnd that di†erent models give slightly di†erent time periods for gas to have such density. The most detailed model ““B of Ciolek & Mous- UV ÏÏ chovias (1995) gives about (5.5È6.7)]106 yr, the model by Li (1998) about (3.5È4.1)]106 yr, and the model by Palla & Galli (1997) about (8.7È13.4)]106 yr for a core with a size of 0.24 pc and magnetic Ðeld strength of 30 kG. Thus present ambipolar di†usion models seem to indicate that detectable cores in our sample will be condensed within about (3.5È13.4)]106 yr, after which the cores will undergo dynamical, star-forming collapse. Thereby, the predicted ratios of [t(life of protostar)]/[t(core formation)] is [(1È5)]105]/[(3.5È13.4)]106]B0.007È0.14, which is smaller than our empirical value (0.31) by a factor of about 2È44. This discrepancy between model predictions and our data is also seen for the Ðve star forming regions ; the empirical ratios are 0.39 (B4/36) for Taurus, 0.46 (B9/41) for Ophiuchus, 0.33 (B9/27) for Lupus, 0.23 (B3/13) for Chamaeleon II and III, and 0.38 (B5/13) for Vela. As a result, the timescale of ambipolar di†usion for core formation in the present models seems to be too long, suggesting that the models of ambipolar di†usion need to be modiÐed or perhaps that faster mechanisms of core formation should be also considered (cf. Tafalla et al. 1998). We suggest that the typical lifetime of starless cores [Z(6È8) ]103 cm~3] may be about 3 times longer than the duration of the class 0 and class I phases, i.e., about (0.3È 1.6]106) yr, which is shorter than the ambipolar model prediction by a factor of 2È44. A similar conclusion was reached by Jijina, Myers, & Adams (1998) based on statistics of NH cores with and without associated stars. 3 3. CONCLUSION In this paper we present a new catalog of 406 dense cores optically selected by using the STScI Digitized Sky Survey (DSS). We have imaged areas of 0.52 or 1.0 deg2 around already known numerous NH and C18O cores, every Lynds class 5 and 6 cloud (Lynds3 1962), and every southern Hartley et al. (1986) class A cloud, to identify every local minimum of intensity in each Ðeld and to select the darkest and best resolved minima. For the identiÐed 406 sources, we used the IRAS Point Source Catalog to determine which have associated point sources and used the criteria for PMS stars by Weintraub (1990) and the catalog of PMS stars by Herbig & Bell (1988) to Ðnd possible PMS stars associated with the cores. From these surveys, 306 starless cores with neither an embedded YSO (EYSO) nor a preÈmainsequence (PMS) star, 94 cores with EYSOs (one core has both an EYSO and a PMS star), and six cores with only a PMS star are found. This list of dense cores will be a useful database for an extensive systematic study of dense cores for a better understanding of the early stages of star formation. Our fairly complete sample of most opaque cores gives representative statistics of physical parameters of dense cores. Most cores are found to have an apparent angular size of 1@È4@ and a linear size of D0.1È0.3 pc, with an average of 0.24 pc. Interestingly, the sizes (mean: 0.33^0.03 pc) of the cores with EYSOs are usually larger than those (mean: 0.21^0.01 pc) of the starless cores. The mean aspect ratio of cores is 2.4^0.1, conÐrming that most cores are more likely elongated than spherical. The ratio of [N(cores with EYSOs)]/[N(starless cores)] for our sample is about 0.31 (B94/306). This value is much higher than expected from the relative time scales ([t(life of protostar)]/[t(core formation)]B[(1È5)]105]/ [(3.5È13.4)]106]B0.007È0.14) of ambipolar di†usion of a core [with gas densityZ(6È8)]103 cm~3] and the life of a protostar. The statistics of our sample indicate that the ambipolar di†usion timescale predicted by present models for dense core formation may be too long. The typical lifetime of starless cores is suggested to be about 3 times longer than the duration of the class 0 and class I phases, i.e., about (0.3È1.6)]106 yr, which is shorter than the ambipolar model predictions by a factor of 2È44. C. W. L acknowledges the Ðnancial support from the 1996 Overseas Postdoctoral Support Program of Korea Research Foundation. C. W. L also thanks the Harvard- Smithsonian Center for Astrophysics for support while working on this project. We would like to thank Lori Allen and August Muench for their careful reading of our manuscript and an anonymous referee for his useful comments. This research was supported by NASA Origins of Solar System Program, grant NAGW-3401. REFERENCES Bachiller, R. 1996, ARA&A, 34,111 Beichman, C. A., Myers, P. C., Emerson, J. P., Harris, S., Mathieu, R., Benson, P. J., & Jennings, R. E. 1986, ApJ, 307, 337 Benson P. J., & Myers P. C. 1989, ApJS, 71, 89 (BM) Bok, B. J., & McCarthy, C. C. 1974, AJ, 79, 42 Bourke, T. L., Hyland, A. R., & Robinson, G. 1995a, MNRAS, 276, 1052 Bourke, T. L., Hyland, A. R., Robinson, G., James, S. D., & Wright, C. M. 1995b,MNRAS, 276, 1067 Carballo, R., & Sahu, M. 1994, A&A, 289, 131 Cernicharo, J., & Bachiller, R. 1984, A&AS, 58, 327 Chen, H., Grenfell, T. G., Myers, P. C., & Hughes, J. D. 1997, ApJ, 478, 295 Chini, R. 1981, A&A, 99, 346 Ciolek, G. E., &Mouschovias, T. Ch. 1995, ApJ, 454, 194 Clark, F. O. 1986, A&A, 164, L19 Clemens, D. P., & Barvainis, R. 1988, ApJS, 68, 257 (CB) Codella, C., Welser, R., Henkel, C., Benson, P. J., & Myers, P. C. 1997, A&A, 324, 203 Cohen, M., & Kuhi, L. V. 1979, ApJS, 41, 743 Dame, T.M., et al. 1987, ApJ, 322, 706 Dame, T.M., & Thaddeus, P. 1985, ApJ, 297, 751 de Geus, E., Bronfman, L., & Thaddeus, P. 1990, A&A, 231, 137 Dickman, R. L. 1978, 37, 407 Elias, J. 1978a, ApJ, 223, 859 ÈÈÈ. 1978b, ApJ, 224, 453 Feitzinger, J. V. & Stu� we, J. A. 1984, A&AS, 58, 365 Felli, M., Palagi, F., & Tofani, G. 1992, A&A, 225, 293 Frerking,M. A., & Langer, W. D. 1982, ApJ, 256, 523 Gauvin, L. S., & Strom, K.M. 1992, ApJ, 385, 217 Goodman, A. A., Benson, P. J., Fuller, G. A., & Myers, P. C. 1993, ApJ, 406, 528 Graham, J. A., & Frogel, J. A. 1985, ApJ, 289, 331 Harjunpaa, P., Liljestrom, T., & Mattila, K. 1991, A&A, 249, 493 Hartley, M., Manchester, R. N., Smith, R.M., Tritton, S. B., & Goss, W. M. 1986, A&AS, 63, 27 (HMSTG) 250 LEE & MYERS Herbig, G. H., & Bell, K. R. 1988, in Third Catalog of Emission-Line Stars of Orion Population, Lick Obs. Bull., 1111 Herbig, G. H., & Jones, B. F. 1983, AJ, 88, 1040 Hetem, J. C. G., Sanzovo, G. C., & Lepine, J. R. D. 1988, A&A, 76, 347 Hilton, J., & Lahulla, J. F. 1995, A&AS, 113, 325 Jijina, J., Myers, P. C., & Adams, F. C. 1998, ApJ, submitted Kenyon, S. J., Hartmann, L., Strom, S. E., & Strom, K.M. 1990, AJ, 99, 869 Kun, M., & Prusti, T. 1993, A&A, 272, 235 Lee, C. W., Myers, P. C., & Tafalla,M. 1999, in preparation Lemme, C., Wilson, T. L., Tieftrunk, A. R., & Henkel, C. 1996, A&A, 312, 585 Leung, C.M., Kutner,M. L., &Mead, K. N. 1982, ApJ, 262, 583 Li, Z.-Y. 1998, ApJ, 493, 230 Lindblad, P. 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J. 1983, ApJ, 264, 517 (MLB) Neckel, T., & Klare, G. 1980, A&AS, 42, 251 Onishi, T., Mizuno, A., Kawamura, A., Ogawa, H., & Fukui, Y. 1996, ApJ, 465, 815 Palla, F., & Galli, D. 1997, ApJ, 476, 38 Postman, M. 1996, in Distribution of the Astronomy Community of the Compressed Digitized Sky Survey (Baltimore: Space Telescope Science Inst.) Rogers, A. W. 1960, MNRAS, 120, 163 Schmidt, E. G. 1975, MNRAS, 172, 401 Schwartz, R. D. 1991, in Low Mass Star Formation in Southern Molecular Clouds, ed. B. Reipurth (ESO Sci. Rep. 11) (Garching: ESO), 93 Shu, F. H., Adams, F. C., & Lizano, S. 1987, ARA&A, 25, 23 Snell, R. L. 1981, ApJS, 45,121 Straizys, V., Cernis, K., Kazlauskas, A., & Meistas, E. 1992, Baltic Astron., 1, 149 Tafalla, M., Mardones, D., Myers, P. C., Caselli, P., Bachiller, R., & Benson, P. J. 1998, ApJ, 504, 900 Tody, D. 1993, in ASP Conf. Ser. 52, Astronomical Data Analysis Software and Systems II, ed. R. J. Hanisch, R. J. V. Brissenden, & J. 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This didn't format well. Please let me know if there is a better way to send papers Thanks --Guastella 20:48, 8 January 2008 (PST) Pete

LDN 1340

--Rebull 20:14, 8 January 2008 (PST) Here's a summary of the latest developments on this object:

One of you (Peter?) suggested this object - and it was a fabulous suggestion. Beautiful in the optical, with IRAS sources, a handful of existing literature, and no Spitzer. Perfect! The icing on the cake was that it's visible in the Spring.

One of you (Peter again?) noticed that there was another AAS poster from 2005 on this object. I mentioned that I knew 2 of the authors (JoAnn O'Linger and Grace Wolf-Chase). Not 2 hours after leaving you, I ran into them. One thing I didn't mention in the context of searching the archive is that there is an open call for proposals out now, eg., there are ~700 proposals for objects that are currently being reviewed, and 20% of them will get their targets approved by March. To some extent, since you're putting in a proposal more or less now, you kind of trump them. On the other hand, it's never good to make enemies.... So, it turns out that JoAnn and collaborators have submitted a proposal to map this region over 1 square degree. There's no guarantee that their data will actually be taken this cycle (before we run out of cryogen in Spring 2009), but at the same time, we probably won't be able to ask for a full square degree (it would take too much time). We could pick a subregion to focus on, or we could find another target entirely.

I'll continue to talk to JoAnn (we had just a brief conversation today), and if I can get her posters (one from before, one from this meeting!), I'll post them here.

[END]

Lynds Target Selection

Contents

LDN 470

LDN 1225

LDN 880

LDN 1340

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