Difference between revisions of "What did luisa do?"
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no additional very red sources found in data. all other sources detected at multiple bands seem to have zero spitzer color, e.g., they are not red. not all of these sources are necessarily stars, but if they are stars, then they don't have any infrared excess and thus we infer no circumstellar dust. | no additional very red sources found in data. all other sources detected at multiple bands seem to have zero spitzer color, e.g., they are not red. not all of these sources are necessarily stars, but if they are stars, then they don't have any infrared excess and thus we infer no circumstellar dust. | ||
HOWEVER, the one visibly red object is quite impressive and very red indeed. | HOWEVER, the one visibly red object is quite impressive and very red indeed. | ||
| + | |||
| + | when we measure spitzer fluxes, we get them back in uJy (or mJy or similar). the 2mass data come to us in magnitudes. we can use both magnitudes and fluxes to assess how red this source is. it is useful thus to convert the measured spitzer fluxes to mags and the 2mass mags to fluxes. in june, we wrote a spreadsheet to do that. let me know if you need a copy, or write one from scratch using the stuff on the L1688 page (or, more specifically, pages it references). | ||
| + | |||
| + | go look at the CMDs and CCDs that people use to find YSOs. i gave you several in the intro ppt, several are buried in the wiki, and you can find many more in the literature. Calculate the colors for our red object and see where it falls in these diagrams. is this a weak or strong excess source? | ||
| + | |||
| + | go look at the SEDs that are expected for YSOs. i gave you several in the intro ppt, several are buried in the wiki, and you can find many more in the literature. plot up the SED for this source. watch your units (as it says elsewhere in the wiki) because this can be VERY tricky. you will find that you are either right or very very wrong (e.g., off by 38 orders of magnitude, etc). see how the SED for this source compares to other YSOs. is this a weak or strong excess source? | ||
taking a shot in the dark, i wrote connelley to see if we could get copies of his fits images from his paper. he obliged and sent them to us, so we now have very deep K-band imaging, much deeper than that from 2mass. but those data don't have any WCS information in the headers, so they are likely to be hard to use in MaxImDL. | taking a shot in the dark, i wrote connelley to see if we could get copies of his fits images from his paper. he obliged and sent them to us, so we now have very deep K-band imaging, much deeper than that from 2mass. but those data don't have any WCS information in the headers, so they are likely to be hard to use in MaxImDL. | ||
| − | + | the SED and a table of the colors can go into the poster. a CMD or CCD with a single point is unlikely to be helpful, but if you wish to put it in context, you can add your point to one of the existing plots you find in the literature or on the wiki and put THAT on the poster. make sure you cite where the original plot came from (and specifically what region the rest of the data points come from). | |
| − | + | ||
| − | + | ultimately, we would like to model this source, looking at the shape of the SED AND (this is important) the morphology of the object as it appears in the deep K image and the irac-1 image. it is interesting that is is not a point but more of a rectangle. this shape plus the SED is telling us something about the nature of the source. | |
| + | good enough to stop here for the poster. | ||
=LDN 981= | =LDN 981= | ||
Revision as of 21:38, 4 December 2008
I made this into a separate page so as not to ruin your discussion among your classes. :)
in the interest of getting information into the page, i am using minimal punctuation and grammar and am being perhaps too brief in some of these steps. let me know when something doesn't make sense.
Left as an exercise for the reader: Compare these steps to those we discussed in June in the Working with L1688 analysis. hint: those steps that seem too briefly summarized HERE have a LOT more explanation on that other page.
LDN 425
NB: discussed in june.
download bcd and pbcd data. likely only to use pbcd, but might as well get bcd now in case i have to reprocess it.
unzip it.
look at pipeline produced mosaics. they look fine. no need to reprocess.
make some 3-color mosaics. note bright red thing in depths of the stuff that is dark in the optical. no other screamingly obvious objects seen in 3-color mosaic as bright red things. another obj seen at 24, but not as red as the first obj.
look in literature for previously known objects. note that the red thing is the same object studied by connelley et al. (2007 AJ 133, 1528).
do photometry, a.k.a. run source extraction (manually on previously known obj, or automatically on everything.) i'm using apex and idl, but APT is also JUST FINE. check source extraction to make sure photometry makes sense and looks good. it does.
no additional very red sources found in data. all other sources detected at multiple bands seem to have zero spitzer color, e.g., they are not red. not all of these sources are necessarily stars, but if they are stars, then they don't have any infrared excess and thus we infer no circumstellar dust. HOWEVER, the one visibly red object is quite impressive and very red indeed.
when we measure spitzer fluxes, we get them back in uJy (or mJy or similar). the 2mass data come to us in magnitudes. we can use both magnitudes and fluxes to assess how red this source is. it is useful thus to convert the measured spitzer fluxes to mags and the 2mass mags to fluxes. in june, we wrote a spreadsheet to do that. let me know if you need a copy, or write one from scratch using the stuff on the L1688 page (or, more specifically, pages it references).
go look at the CMDs and CCDs that people use to find YSOs. i gave you several in the intro ppt, several are buried in the wiki, and you can find many more in the literature. Calculate the colors for our red object and see where it falls in these diagrams. is this a weak or strong excess source?
go look at the SEDs that are expected for YSOs. i gave you several in the intro ppt, several are buried in the wiki, and you can find many more in the literature. plot up the SED for this source. watch your units (as it says elsewhere in the wiki) because this can be VERY tricky. you will find that you are either right or very very wrong (e.g., off by 38 orders of magnitude, etc). see how the SED for this source compares to other YSOs. is this a weak or strong excess source?
taking a shot in the dark, i wrote connelley to see if we could get copies of his fits images from his paper. he obliged and sent them to us, so we now have very deep K-band imaging, much deeper than that from 2mass. but those data don't have any WCS information in the headers, so they are likely to be hard to use in MaxImDL.
the SED and a table of the colors can go into the poster. a CMD or CCD with a single point is unlikely to be helpful, but if you wish to put it in context, you can add your point to one of the existing plots you find in the literature or on the wiki and put THAT on the poster. make sure you cite where the original plot came from (and specifically what region the rest of the data points come from).
ultimately, we would like to model this source, looking at the shape of the SED AND (this is important) the morphology of the object as it appears in the deep K image and the irac-1 image. it is interesting that is is not a point but more of a rectangle. this shape plus the SED is telling us something about the nature of the source.
good enough to stop here for the poster.
LDN 981
download bcd and pbcd data. likely only to use pbcd, but might as well get bcd now in case i have to reprocess it.
unzip it.
look at pipeline produced mosaics. they look fine. no need to reprocess.
do photometry, a.k.a. run source extraction (i'm using apex and for irac, idl as well, but APT is also JUST FINE). check source extraction to make sure photometry makes sense and looks good. it does.
color-based selection of YSOs suggests the following candidates (NOTE THAT names are not static, and you should refer to these by their full coordinates until we establish a final real list):
981-01 20 59 39.5 +50 21 24 981-02 20 59 47.9 +50 14 32 981-03 21 00 17.3 +50 19 40 981-04 21 00 17.4 +50 19 40 ** 981-05 21 00 37.0 +50 20 58 ** 981-06 21 00 46.3 +50 23 45 981-07 21 00 49.1 +50 15 25 981-08 21 00 49.5 +50 15 43 981-09 21 00 54.7 +50 26 17 ** 981-10 21 01 20.3 +50 20 08 ** 981-11 21 01 42.1 +50 13 05 981-12 21 01 47.5 +50 18 22
ones with "**" found in more than 1 CMD, suggests likely YSO?
go get literature. quanz paper leads us to feigelson and kriss paper. feigelson and kriss report only names and finder charts; need to go to 2mass to extract high-quality modern coordinates. use finder chart to reconstruct whch obj and make note of coords and JHK mags. can find all but one based on finder chart, comparing images. got new 2mass coords for all of those:
\char comment = cleaned-up feigelson & kriss catalog
| name |RA |Dec |
| |d |d |
1 315.511000 50.495400
2 315.473400 50.537900
3 315.362247 50.528336
4 315.304731 50.401846
5 315.287700 50.361600
6 315.244400 50.403600
7 315.184000 50.488800
8 315.172215 50.495880
9 315.155700 50.500000
10 315.134800 50.527100
12 315.022700 50.437300
13 315.070701 50.401503
14 315.136002 50.363911
15 315.041164 50.352451
16 315.175594 50.259917
17 315.182015 50.204971
18 315.221231 50.271915
19 315.285914 50.260887
20 315.355610 50.330031
21 315.344357 50.360091
22 315.536100 50.378600
find 9 with counterparts in our images, none of which are disk
candidates based on above:
fk15 21 00 09.9 +50 21 09 fk13 21 00 17.0 +50 24 05 fk14 21 00 32.6 +50 21 50 fk 8 21 00 41.3 +50 29 45 fk17 21 00 43.7 +50 12 18 fk18 21 00 53.1 +50 16 19 fk19 21 01 08.6 +50 15 39 fk 4 21 01 13.2 +50 24 07 fk21 21 01 22.7 +50 21 36
haven't made SEDs of any of these yet. will need to make for you the CMDs I used to pick obj above, and to see where the fk objects fall in the same CMDs. soon!
also need to copy here the full photometry i have for these objects. i have it, just haven't copied it here yet, sorry. will want to compare your photometry and mine, as we did for the other cloud in june.
