LLAMMa Resolution Worksheet - Revision history

Rebull at 04:20, 30 March 2016

2016-03-30T04:20:55Z

Rebull: /* Getting started: what sizes do we expect? */

2016-03-15T04:06:16Z

Getting started: what sizes do we expect?

Rebull: /* Obtaining images of our region, and resolution of various surveys */

2016-03-15T04:05:23Z

Obtaining images of our region, and resolution of various surveys

Rebull: /* Next steps directly related to these skills and issues */

2016-03-09T22:18:45Z

Next steps directly related to these skills and issues

Rebull: /* Pulling it all together */

2016-03-09T22:14:13Z

Pulling it all together

Rebull: /* Comparing resolution of various surveys, and why it matters */

2016-03-09T22:13:05Z

Comparing resolution of various surveys, and why it matters

Rebull: /* Comparing resolution of various surveys, and why it matters */

2016-03-09T22:09:43Z

Comparing resolution of various surveys, and why it matters

Rebull: /* Comparing resolution of various surveys, and why it matters */

2016-03-09T22:08:20Z

Comparing resolution of various surveys, and why it matters

Rebull at 19:47, 2 March 2016

2016-03-02T19:47:43Z

Rebull at 15:49, 2 March 2016

2016-03-02T15:49:13Z

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 For a general introduction, please start with the main text already on the wiki for [[Resolution]]. Please also look at the examples lower on that page, but you don't need to actually do the one that suggests that you go download data, etc.  The skills you might have gained from that specific example will be stuff that we do as part of our project.
-We will be using [http://irsa.ipac.caltech.edu/applications/finderchart/ FinderChart] at IRSA to retrieve images, but we will also use [http://skyview.gsfc.nasa.gov/ Goddard's Skyview] to retrieve larger FITS images. You need a way to view and interact with FITS files (see FITS explanation below). FinderChart (and its more generic friend [http://irsa.ipac.caltech.edu/fftools/app.html IRSA Viewer]) allow you to interact directly with the FITS files. You could also use DS9 which you can download here: [http://hea-www.harvard.edu/RD/ds9/ DS9].  Also, ds9 was the topic of a tutorial in [http://nitarp.ipac.caltech.edu/resource/8 NITARP tutorials].
+We will be using [http://irsa.ipac.caltech.edu/applications/finderchart/ FinderChart] at IRSA to retrieve images, but we will also use [http://skyview.gsfc.nasa.gov/ Goddard's Skyview] to retrieve larger FITS images. You need a way to view and interact with FITS files (see FITS explanation below). FinderChart (and its more generic friend [http://irsa.ipac.caltech.edu/irsaviewer/app.html IRSA Viewer]) allow you to interact directly with the FITS files. You could also use DS9 which you can download here: [http://hea-www.harvard.edu/RD/ds9/ DS9].  Also, ds9 was the topic of a tutorial in [http://nitarp.ipac.caltech.edu/resource/8 NITARP tutorials].
 =Skyview basics and other things to note=
@@ Line 64: / Line 64: @@
 ==FITS Viewers: FinderChart (and IRSA Viewer)==
-[http://irsa.ipac.caltech.edu/applications/finderchart/ FinderChart] and [http://irsa.ipac.caltech.edu/fftools/app.html IRSA Viewer] both use software that is called "Firefly", and both tools have a similar look-and-feel. FinderChart was originally designed to create finder charts for use at a telescope, but it has evolved into one of IRSA's most popular tools. It provides images from up to 5 surveys in up to 21 bands, and allows simultaneous searches of the corresponding catalogs. IRSA Viewer is a more generic version of FinderChart, providing the FITS viewer and one-by-one image retrieval and catalog searches.
+[http://irsa.ipac.caltech.edu/applications/finderchart/ FinderChart] and [http://irsa.ipac.caltech.edu/irsaviewer/app.html IRSA Viewer] both use software that is called "Firefly", and both tools have a similar look-and-feel. FinderChart was originally designed to create finder charts for use at a telescope, but it has evolved into one of IRSA's most popular tools. It provides images from up to 5 surveys in up to 21 bands, and allows simultaneous searches of the corresponding catalogs. IRSA Viewer is a more generic version of FinderChart, providing the FITS viewer and one-by-one image retrieval and catalog searches.
 In both cases, the search capability is integrated with the FITS viewer capability. (In Skyview, these capabilities are not integrated.)  When FinderChart or IRSA Viewer give you images as a result of a search, you are looking at (and interacting with) the original FITS files. There is a toolbox on the top of both tools that can be used with the images. You can change color stretches and color tables, you can leave markers on the image, you can read in catalogs (and ds9 regions files), etc. In FinderChart, by default, all the images are locked together, so what you do to one image (zoom, etc.), happens to all of them.  (To unlock them, click on the lock icon in the image toolbox.) (Just for completeness, in IRSA Viewer, there is no ''a priori'' guarantee that the images that are loaded are of the same patch of sky, so they are by default NOT locked.)

@@ Line 92: / Line 92: @@
 Googling to get what you need is ok!
-Let's start by calibrating our expectations.
+Let's start by calibrating our expectations by thinking about the sizes of things in arcseconds (or arcminutes or degrees) with which we are more familiar before launching into measuring things on the FITS images.
 *'''Q1.1:''' What approximate angular size is the Moon?
 *'''Q1.2:''' What approximate angular size is Jupiter?

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	Go to [http://irsa.ipac.caltech.edu/applications/finderchart/ FinderChart] and ask it for images that are at least 20 arcmin on a side (you could go to half-degree- or degree-size images if you want) at that coordinate for POSS, SDSS, 2MASS, WISE, and IRAS. (Don't forget IRAS too!) Turn off catalog searching for now because otherwise it gets just too confusing.		Go to [http://irsa.ipac.caltech.edu/applications/finderchart/ FinderChart] and ask it for images that are at least 20 arcmin on a side (you could go to half-degree- or degree-size images if you want) at that coordinate for POSS, SDSS, 2MASS, WISE, and IRAS. (Don't forget IRAS too!) Turn off catalog searching for now because otherwise it gets just too confusing.
		+
		+	''All units here should be arcseconds (or arcminutes or degrees).''

	'''Q2.1 :''' For the images that it returns, what is the size of each pixel for each survey? (Make the image big enough in your view of it that you can see pixels, and measure the size of it.) Try at least one image from each of the surveys. Most of these surveys were electronic from the start; however, the original POSS was photographs, so the spatial resolution was set by the seeing at Palomar that night, AND the size of the silver grains on the photographic emulsion. When the plates got scanned, during the digitization process, this got mapped into the pixels you see in the images.		'''Q2.1 :''' For the images that it returns, what is the size of each pixel for each survey? (Make the image big enough in your view of it that you can see pixels, and measure the size of it.) Try at least one image from each of the surveys. Most of these surveys were electronic from the start; however, the original POSS was photographs, so the spatial resolution was set by the seeing at Palomar that night, AND the size of the silver grains on the photographic emulsion. When the plates got scanned, during the digitization process, this got mapped into the pixels you see in the images.

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 =Next steps directly related to these skills and issues=
-For our project, we have a list of "things in which we are interested" which consists of (a) objects Xavier identified one way or another as possible YSOs; (b) objects from the literature that someone identified as interesting (OB stars, carbon stars, halpha stars). This list of sources is inhomogeneous in that some sources come from WISE directly, and some come from other observations. Our path forward:
+For our project, we have a list of "things in which we are interested" which consists of (a) objects we (well, Rob Gutermuth) identified via IR colors as possible YSOs; (b) objects that we (well, Scott Wolk and I) identified from their X-ray properties as possible YSOs; (c) objects that we (well, I) identified from their light curves as possible variables (which are likely but not guaranteed by any means to be YSOs); (d) objects from the literature that someone identified as interesting -- Halpha stars and the SCUBA sources. This list of sources is inhomogeneous in that sources come from many different observations. Our path forward:
-* Assemble list of objects from the literature.
+* Assemble list of objects from SCUBA. Make sure that we have matched them appropriately in the catalog. There may be some we can't do anything about until we have the Herschel data to link us between 24 um and 450/850 um. (Will use FinderChart for this.)
-* For each of those objects, make sure that we are confident in which source it matches in 2MASS/WISE at least. (Will use FinderChart for this.)
+* Take net list of "things in which we are interested" (e.g., candidate YSOs) and pass it to FinderChart for POSS/SDSS/2MASS/WISE; take notes on which look like point sources and which look like artifacts or non-point-sources.
 * If at all possible, also look at these objects (those surviving prior step) in GLIMPSE and IPHAS using ds9. (This will be a little harder than FinderChart in that it has a little steeper learning curve to make it work smoothly.)  Take notes on which look like point sources and which may be breaking into pieces in the higher-resolution images.

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 # Is is possible that the sources seen as individual with WISE will break into pieces when viewed with IRAC?
 # Is there any guarantee that a single source seen with IRAC is really a single object?
 =Postscript on the resolution issues: Slight improvements are sometimes possible=

@@ Line 139: / Line 139: @@
 '''Q3.2 :''' Include some GLIMPSE images (IRAC 1 and 2) in your resolution experiments. (You can get them from me or from the Contributed Products from GLIMPSE in the [http://sha.ipac.caltech.edu/applications/Spitzer/SHA/#id=SearchByPosition&RequestClass=ServerRequest&DoSearch=true&SearchByPosition.field.radius=0.3333333334&UserTargetWorldPt=346.40118;62.54626;EQ_J2000&TargetPanel.field.targetName=J230536.28+623246.5&SimpleTargetPanel.field.resolvedBy=nedthensimbad&MoreOptions.field.prodtype=aor,pbcd,supermosaic,inventory&InventorySearch.radius=0.3333333334&shortDesc=Position&isBookmarkAble=true&isDrillDownRoot=true&isSearchResult=true Spitzer Heritage Archive]. (Be a little careful because this search will give you more images than you really need; you want the tile GLM_11150+0235* -- look where the blue circle (your target) falls on the image.) Here the PSF is distinctly triangular, even for isolated sources.
-'''Q3.3 :''' For each of the following sources, can you find the counterparts between 2MASS and WISE (ch 1 and 2)? Bonus points if you give me the coordinate-based names from WISE and 2MASS '''and''' GLIMPSE. (Hint: catalog search in FinderChart.) (If you want, regions file of these sources: <FONT COLOR="RED">STOPPING UPDATING HERE</FONT>[[file:section3sources.reg.txt]] - save that actual file (not the wiki link) to disk and change filename to remove the .txt extension, leaving .reg for use in ds9 or FinderChart/IRSA Viewer)
+'''Q3.3 :''' For each of the following sources, can you find the counterparts between 2MASS and WISE (ch 1 and 2)? Bonus points if you give me the coordinate-based names from WISE and 2MASS '''and''' GLIMPSE. (Hint: catalog search in FinderChart.) (If you want, regions file of these sources: [[file:section3sourcescepc.reg.txt]] - save that actual file (not the wiki link) to disk and change filename to remove the .txt extension, leaving .reg for use in ds9 or FinderChart/IRSA Viewer)
 Easy :

← Older revision		Revision as of 22:09, 9 March 2016
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−	'''Q3.4 :''' So, knowing what you do now, why is it that IRAS sources are given as, e.g., "IRAS 23038+6215" and 2MASS sources are given as, e.g., "2MASS 23053628+~~6232465~~" ?	+	'''Q3.4 :''' So, knowing what you do now, why is it that IRAS sources are given as, e.g., "IRAS 23038+6215" and 2MASS sources are given as, e.g., "2MASS 23053628+6232466" ?

	=Pulling it all together=		=Pulling it all together=

@@ Line 137: / Line 137: @@
 '''Aside''': You can also blink images in FinderChart or ds9, which sometimes is more helpful for seeing differences than a 3-color image -- in order to do this in ds9, either use the command line (ds9 *fits) or start ds9, then do file/open and find the first image; do frame/new then file/open and load the second image, etc. If you used the command line trick, you will load all the images into individual tiles, in alphabetical order (which is most likely not wavelength order!). If you did them one-by-one, you will have them virtually in a stack, in the order you loaded them. To see all of them at once, click on 'frame' then 'tile.' To get it back to one at a time (in a virtual stack), pick 'single.' To line them up on the sky, pick from the top "frame" menu/match/frame/wcs to match them in terms of area on the sky. (That command means, "align all the images I have loaded in ds9 to be North up, all on the same spatial scale as the image I have selected when I initiate this command." WCS stands for world coordinate system, meaning that there is information about the ra, dec, and mapping of pixels to ra and dec in the FITS header.) To scroll through the whole stack, pick 'next' or 'previous', or go ahead and blink them. You can configure the length of time spent on each frame. You can change the ordering - explore the menu options on the top "Frame" menu.  In the 'single' frame case, the image you are looking at is the active one; in the 'tile' view, the one with the blue outline is the active one. Click on the tile to make it the active one.
-'''Q3.2 :''' Include some GLIMPSE images (IRAC 1 and 2) in your resolution experiments. (You can get them from me or from the Contributed Products from GLIMPSE in the [http://sha.ipac.caltech.edu/applications/Spitzer/SHA/#id=SearchByPosition&RequestClass=ServerRequest&DoSearch=true&SearchByPosition.field.radius=0.13888889000000001&UserTargetWorldPt=346.4625;62.515277777777776;EQ_J2000&SimpleTargetPanel.field.resolvedBy=nedthensimbad&MoreOptions.field.prodtype=aor,pbcd,inventory&InventorySearch.radius=0.13888889000000001&shortDesc=Position&isBookmarkAble=true&isDrillDownRoot=true&isSearchResult=true Spitzer Heritage Archive]. Here the PSF is distinctly triangular, even for isolated sources.
+'''Q3.2 :''' Include some GLIMPSE images (IRAC 1 and 2) in your resolution experiments. (You can get them from me or from the Contributed Products from GLIMPSE in the [http://sha.ipac.caltech.edu/applications/Spitzer/SHA/#id=SearchByPosition&RequestClass=ServerRequest&DoSearch=true&SearchByPosition.field.radius=0.3333333334&UserTargetWorldPt=346.40118;62.54626;EQ_J2000&TargetPanel.field.targetName=J230536.28+623246.5&SimpleTargetPanel.field.resolvedBy=nedthensimbad&MoreOptions.field.prodtype=aor,pbcd,supermosaic,inventory&InventorySearch.radius=0.3333333334&shortDesc=Position&isBookmarkAble=true&isDrillDownRoot=true&isSearchResult=true Spitzer Heritage Archive]. (Be a little careful because this search will give you more images than you really need; you want the tile GLM_11150+0235* -- look where the blue circle (your target) falls on the image.) Here the PSF is distinctly triangular, even for isolated sources.
-'''Q3.3 :''' For each of the following sources, can you find the counterparts between IRAC (from GLIMPSE, ch 1 and 2) and WISE (ch 1 and 2)? Bonus points if you give me the coordinate-based names from WISE and 2MASS and GLIMPSE. (Hint: catalog search in FinderChart.) (If you want, regions file of these sources: <FONT COLOR="RED">STOPPING UPDATING HERE</FONT>[[file:section3sources.reg.txt]] - save that actual file (not the wiki link) to disk and change filename to remove the .txt extension, leaving .reg for use in ds9 or FinderChart/IRSA Viewer)
+'''Q3.3 :''' For each of the following sources, can you find the counterparts between 2MASS and WISE (ch 1 and 2)? Bonus points if you give me the coordinate-based names from WISE and 2MASS '''and''' GLIMPSE. (Hint: catalog search in FinderChart.) (If you want, regions file of these sources: <FONT COLOR="RED">STOPPING UPDATING HERE</FONT>[[file:section3sources.reg.txt]] - save that actual file (not the wiki link) to disk and change filename to remove the .txt extension, leaving .reg for use in ds9 or FinderChart/IRSA Viewer)
-Easy (do the first two together):
+Easy :
-*Source at 5:28:17.12, +34:28:04.1 (an Halpha source from Jose et al.)
+*Source at 23:05:36.28 +62:32:46.5 (the Halpha source from Mikami et al.)
-*Source at 5:28:16.07, +34:27:28.8 (quite near the above one, an Halpha source from Jose et al.)  (Bonus: distance between them?)
+*Source at 23:06:38.24 +62:32:04.1 (the Halpha source from Witham et al.)
-*Source at 5:29:03.31, +34:24:13.6
+A bit harder:
 Hard:
-*Source at 5:28:07.00, +34:25:27.0 (An OB star from Jose et al.)
+*Source at 23:05:10.77 +62:27:18.7 (why do I have this in the "hard" bin?)
-*Source at 5:28:05.72, +34:25:28.1 (Another OB star from Jose et al.)
+*Source at 23:05:12.44 +62:29:41.9 (why do I have this in the "hard" bin? Hint: you need GLIMPSE.)
 Really hard:
-*5:28:06.000, +34:25:00.00 (Another OB star from Jose et al.)
+*23:06:29.75 +62:26:11.7 (why do I have this in the "hard" bin? Hint: you need SDSS)
-'''Q3.4 :''' So, knowing what you do now, why is it that IRAS sources are given as, e.g., "IRAS 23038+6215" and 2MASS sources are given as, e.g., "2MASS 21402612+5814243" ?
+'''Q3.4 :''' So, knowing what you do now, why is it that IRAS sources are given as, e.g., "IRAS 23038+6215" and 2MASS sources are given as, e.g., "2MASS 23053628+6232465" ?
 =Pulling it all together=

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 =Skyview basics and other things to note=
-==Background information I'm assuming you know==
+==Background information==
 If you need a refresher on mosaics, see [[What is a mosaic and why should I care?]]

@@ Line 102: / Line 102: @@
 THE POINT OF DOING THIS: will we see any disks or rings around our stars using our data? You may need the resolution information from the below to answer this. :)  Having gotten the answer to this, you will be met with a Paddington Bear-style "hard stare" if I hear you telling anyone that the "rings" in the MIPS-24 data are rings of dust around those stars.
-=FinderChart: Obtaining images of our region, and resolution of various surveys=
+=Obtaining images of our region, and resolution of various surveys=
 We are studying a square that is ~18-20 arcmin on a side, centered on 23:05:51 +62:30:55. (bonus: what is that in decimal degrees?)