L1688 Resolution Worksheet - Revision history

Rebull: /* Calibrating your expectations for point sources: what sizes do we expect? */

2018-04-11T15:39:15Z

Calibrating your expectations for point sources: what sizes do we expect?

Rebull: /* Calibrating your expectations for point sources: what sizes do we expect? */

2018-04-11T15:38:56Z

Calibrating your expectations for point sources: what sizes do we expect?

Rebull at 21:44, 10 April 2018

2018-04-10T21:44:36Z

Rebull: /* Spitzer and Cores-to-Disks */

2018-04-10T21:34:36Z

Spitzer and Cores-to-Disks

Rebull: /* Spitzer and Cores-to-Disks */

2018-04-10T21:33:43Z

Spitzer and Cores-to-Disks

Rebull: /* Part 1: What size region should we study? */

2018-04-10T21:31:58Z

Part 1: What size region should we study?

Rebull: /* Notes on Distances */

2018-04-10T21:31:30Z

Notes on Distances

Rebull: /* Introduction */

2018-04-10T21:27:29Z

Introduction

Rebull: /* Introduction */

2018-04-10T21:26:41Z

Introduction

Rebull: /* Specific sources in our region */

2018-03-15T17:09:54Z

Specific sources in our region

@@ Line 171: / Line 171: @@
 *'''Q2.5:''' The disk around beta Pictoris is about 1650 AU in radius. (Beta Pic's parallax is 51.44 mas.) What angular size would that be? (Again, though, the brightnesses are so different, in order to see the disk at all, you have to block out the brightness of the central star and integrate for a long time.)
 *'''Q2.6:''' L1688 is about 120 pc away. Put a star/disk system just like Beta Pictoris in L1688. What size would it be, ignoring issues of surface brightness and contrast with the star?
-*BONUS: [https://www.eso.org/public/images/eso1811c/ | This image] just came out in a press release. It is of IM Lupi. I get 25.47 mas parallax from Hipparcos. From the [http://www.eso.org/public/archives/releases/sciencepapers/eso1811/eso1811a.pdf | journal article], I get 300-900 AU disk radius. How big across is the disk in this image?
+*BONUS: [https://www.eso.org/public/images/eso1811c/ This image] just came out in a press release. It is of IM Lupi. I get 25.47 mas parallax from Hipparcos. From the [http://www.eso.org/public/archives/releases/sciencepapers/eso1811/eso1811a.pdf journal article], I get 300-900 AU disk radius. How big across is the disk in this image?
 THE POINT OF DOING THIS PART: 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.

@@ Line 171: / Line 171: @@
 *'''Q2.5:''' The disk around beta Pictoris is about 1650 AU in radius. (Beta Pic's parallax is 51.44 mas.) What angular size would that be? (Again, though, the brightnesses are so different, in order to see the disk at all, you have to block out the brightness of the central star and integrate for a long time.)
 *'''Q2.6:''' L1688 is about 120 pc away. Put a star/disk system just like Beta Pictoris in L1688. What size would it be, ignoring issues of surface brightness and contrast with the star?
 THE POINT OF DOING THIS PART: 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.

@@ Line 214: / Line 214: @@
 =Pulling it all together=
-Recall that '''THE POINT''' of doing this is to start to develop a sense of (1) what resolution these various telescopes have (and how to get reliable images out of these tools); and (2) why this matters for our multi-wavelength catalog merging.  Is this starting to make more sense?
+Recall that '''THE POINT''' of doing this is (1) pick our region! (2) develop a sense of what resolution means and how it changes between telescopes, e.g., WISE vs. Spitzer vs. 2MASS vs. Herschel resolution. (3) understand what the challenges will be for us in matching across wavelengths.  Is this starting to make more sense?
 Questions to be sure you know the answer to (for reference, I guess these are Q3.x):

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 Skyview won't give you Spitzer images, because Spitzer isn't an all-sky survey. But there are lots of large images available at IRSA from Spitzer. SEIP = Spitzer Enhanced Imaging Products, but this too works in tiles, and the request you give Finder Chart runs off the edges of some of those tiles. There are data there, just not in the tile that Finder Chart is pulling for you here.
-Spitzer was the first NASA mission (or observatory of any sort) to specifically solicit large, coherent projects before launch and require those teams to deliver data products back to the community. The reason for this was that, if something catastrophic happened and Spitzer broke quickly, by conducting these large, coherent investigations right out of the gate, then at least we'd have all these large, coherent data sets. Spitzer has been working for more than 3 times its nominal lifetime now, so that's not a concern. However, part of the deal with these early teams was that these teams would deliver products back to IRSA for distribution. Through this, we have changed the astronomy culture, and many people after that very first cycle have delivered products back to IRSA for distribution. Cores-to-disks (c2d, definitely *not* C2D) was one of those very first teams. They set out to make large maps of several famous star forming regions ... including L1688.  Their delivered products are curated [http://irsa.ipac.caltech.edu/data/SPITZER/C2D/overview.html here] at IRSA.  They delivered maps of large regions as well as specific cores. You can go and get their data (stuff they delivered back to us, both images and catalogs). For this exercise, you want images of *cloud* (big maps) (as opposed to cores) and things marked "Oph" (for rho Ophiuchus, another name for this big SFR).
+Spitzer was the first NASA mission (or observatory of any sort) to specifically solicit large, coherent projects before launch and require those teams to deliver data products back to the community. The reason for this was that, if something catastrophic happened and Spitzer broke quickly, by conducting these large, coherent investigations right out of the gate, then at least we'd have all these large, coherent data sets. Spitzer has been working for more than 3 times its nominal lifetime now, so that's not a concern. However, part of the deal with these early teams was that these teams would deliver products back to IRSA for distribution. Through this, we have changed the astronomy culture, and many people after that very first cycle have delivered products back to IRSA for distribution. Cores-to-disks (c2d, definitely *not* C2D) was one of those very first teams. They set out to make large maps of several famous star forming regions ... including L1688.  Their delivered products are curated [http://irsa.ipac.caltech.edu/data/SPITZER/C2D/overview.html here] at IRSA.  They delivered maps of large regions as well as specific cores. You can go and get their data (stuff they delivered back to us, both images and catalogs). For this exercise, you want images of the *cloud* (big map) (as opposed to individual, much smaller, cores) and things marked "Oph" (for rho Ophiuchus, another name for this big SFR).
 '''Q1.6 :''' Figure out how to get images. You can load them directly into IRSA Viewer from these pages. Some of the images will be very large, because they cover essentially all of the rho Ophiuchus region; if you load from this page into IRSA Viewer, you'll be using only Caltech's network, not your school's...

@@ Line 127: / Line 127: @@
 Skyview won't give you Spitzer images, because Spitzer isn't an all-sky survey. But there are lots of large images available at IRSA from Spitzer. SEIP = Spitzer Enhanced Imaging Products, but this too works in tiles, and the request you give Finder Chart runs off the edges of some of those tiles. There are data there, just not in the tile that Finder Chart is pulling for you here.
-Spitzer was the first NASA mission (or observatory of any sort) to specifically solicit large, coherent projects before launch. The reason for this was that, if something catastrophic happened and Spitzer broke quickly, by conducting these large, coherent investigations right out of the gate, then at least we'd have all these large, coherent data sets. Spitzer has been working for more than 3 times its nominal lifetime now, so that's not a concern. However, part of the deal with these early teams was that these teams would deliver products back to IRSA for distribution. Through this, we have changed the astronomy culture, and many people after that very first cycle have delivered products back to IRSA for distribution. Cores-to-disks (c2d, definitely *not* C2D) was one of those very first teams. They set out to make large maps of several famous star forming regions ... including L1688.  Their delivered products are curated [http://irsa.ipac.caltech.edu/data/SPITZER/C2D/overview.html here] at IRSA.  They delivered maps of large regions as well as specific cores. You can go and get their data (stuff they delivered back to us, both images and catalogs). For this exercise, you want images of *cloud* (big maps) (as opposed to cores) and things marked "Oph" (for rho Ophiuchus, another name for this big SFR).
+Spitzer was the first NASA mission (or observatory of any sort) to specifically solicit large, coherent projects before launch and require those teams to deliver data products back to the community. The reason for this was that, if something catastrophic happened and Spitzer broke quickly, by conducting these large, coherent investigations right out of the gate, then at least we'd have all these large, coherent data sets. Spitzer has been working for more than 3 times its nominal lifetime now, so that's not a concern. However, part of the deal with these early teams was that these teams would deliver products back to IRSA for distribution. Through this, we have changed the astronomy culture, and many people after that very first cycle have delivered products back to IRSA for distribution. Cores-to-disks (c2d, definitely *not* C2D) was one of those very first teams. They set out to make large maps of several famous star forming regions ... including L1688.  Their delivered products are curated [http://irsa.ipac.caltech.edu/data/SPITZER/C2D/overview.html here] at IRSA.  They delivered maps of large regions as well as specific cores. You can go and get their data (stuff they delivered back to us, both images and catalogs). For this exercise, you want images of *cloud* (big maps) (as opposed to cores) and things marked "Oph" (for rho Ophiuchus, another name for this big SFR).
 '''Q1.6 :''' Figure out how to get images. You can load them directly into IRSA Viewer from these pages. Some of the images will be very large, because they cover essentially all of the rho Ophiuchus region; if you load from this page into IRSA Viewer, you'll be using only Caltech's network, not your school's...

@@ Line 96: / Line 96: @@
 The point of this exercise is to narrow down our region. The skills you're going to need here include: finding data, loading and viewing FITS images, aligning the images so that they all cover the same region of the sky, overlaying regions, changing the color stretch and maybe the color table.
-The reason I want you to pull the data from IRSA directly and not just grab the copies of my Box drive is so that you know how to find data after your work on this team is done.
+The reason I want you to pull the data from IRSA directly and not just grab the copies off my Box drive is so that you know how to find data after your work on this team is done.
 ==Finder Chart: DSS, 2MASS, WISE, SEIP, AKARI, IRAS... ==

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 Technically, to be absolutely correct, because you are calculating distances on a sphere, in order to do this, you need to do spherical trigonometry. This matters because the angle subtended by 1 hour of RA on the celestial equator is much larger than that subtended by 1 hour of RA near the celestial pole. For quick and dirty purposes, it should be mostly fine to simply subtract the RA and Dec to get a reasonable estimate of the distance BUT WATCH YOUR UNITS because RA by default is in hours:min of time:sec of time, not deg:arcmin:arcsec.
-The spherical trig does make a difference, though. See [http://spiff.rit.edu/classes/phys301/lectures/precession/precession.html#sep this excerpt from someone's class notes] with some really nice graphics and explanations of why you need to do this, and how to do it right. (hint: For the distances we'll consider here, you need a cosine of the declination. I won't make you do the full spherical trig in most cases.) For the ambitious, anticipating skills you'll need downstream from this worksheet, try programming a spreadsheet to do this for you, given two RA,Dec position pairs. '''NB: Be sure to watch your units on the Dec-- some cosine functions want radians, and some take degrees.'''  (Bonus: how much of a difference in L1688 does it make if you leave out the cos(dec) term? Is that going to get worse or better if we move closer to the north celestial pole?)
+The spherical trig does make a difference, though. See [http://spiff.rit.edu/classes/phys301/lectures/precession/precession.html#sep this excerpt from someone's class notes] with some really nice graphics and explanations of why you need to do this, and how to do it right. (hint: cosine of the declination.) For the ambitious, anticipating skills you'll need downstream from this worksheet, try programming a spreadsheet to do this for you, given two RA,Dec position pairs. '''NB: Be sure to watch your units on the Dec-- some cosine functions want radians, and some take degrees.'''  (Bonus: how much of a difference in L1688 does it make if you leave out the cos(dec) term? Is that going to get worse or better if we move closer to the north celestial pole?)
 =Part 1: What size region should we study?=

@@ Line 4: / Line 4: @@
 The spatial resolution of various instruments and missions is a very important thing for us to consider in the course of our work. We're using data that come from several different surveys, with different spatial resolution. This is most vividly seen by a comparison of WISE channel 1 and 2 with Spitzer IRAC channel 1 and 2 because the wavelengths are very similar (and the telescopes are different). Spatial resolution differences will matter a lot in particular for the Herschel data.
-'''MY GOALS''' for you in doing this are to develop a sense of (1) what resolution means and how it changes between telescopes, e.g., WISE vs. Spitzer vs. 2MASS vs. Herschel resolution; and (2) understand what the challenges will be for us in matching across wavelengths. '''Ancillary goals''' (e.g., you can't do this worksheet without also accomplishing these): (1) get used to working with FITS files, manipulating stretches, etc.; (2) identifying objects in and measuring distances on FITS files; (3) learn how to use Finder Chart (and other IRSA tools), ds9, and Skyview as resources to be used down the road on whatever you find yourself doing next.
+'''MY GOALS''' for you in doing this are to (1) pick our region! (2) develop a sense of what resolution means and how it changes between telescopes, e.g., WISE vs. Spitzer vs. 2MASS vs. Herschel resolution. (3) understand what the challenges will be for us in matching across wavelengths. '''Ancillary goals''' (e.g., you can't do this worksheet without also accomplishing these): (1) get used to working with FITS files, manipulating stretches, etc.; (2) identifying objects in and measuring distances on FITS files; (3) learn how to use Finder Chart (and other IRSA tools), ds9, and Skyview as resources to be used down the road on whatever you find yourself doing next.
 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.

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 =Introduction=
-The spatial resolution of various instruments and missions is a very important thing for us to consider in the course of our work. We're using data that come from several different surveys, with different spatial resolution. This is most vividly seen by a comparison of WISE channel 1 and 2 with Spitzer IRAC channel 1 and 2 because the wavelengths are the same (and the telescopes are different), but it will matter a lot in particular for the Herschel data.
+The spatial resolution of various instruments and missions is a very important thing for us to consider in the course of our work. We're using data that come from several different surveys, with different spatial resolution. This is most vividly seen by a comparison of WISE channel 1 and 2 with Spitzer IRAC channel 1 and 2 because the wavelengths are very similar (and the telescopes are different). Spatial resolution differences will matter a lot in particular for the Herschel data.
 '''MY GOALS''' for you in doing this are to develop a sense of (1) what resolution means and how it changes between telescopes, e.g., WISE vs. Spitzer vs. 2MASS vs. Herschel resolution; and (2) understand what the challenges will be for us in matching across wavelengths. '''Ancillary goals''' (e.g., you can't do this worksheet without also accomplishing these): (1) get used to working with FITS files, manipulating stretches, etc.; (2) identifying objects in and measuring distances on FITS files; (3) learn how to use Finder Chart (and other IRSA tools), ds9, and Skyview as resources to be used down the road on whatever you find yourself doing next.

@@ Line 206: / Line 206: @@
 *16:27:11.739,-24:38:32.19
 *16:27:09.430,-24:37:19.71
-Call them up in whatever FITS viewer works for you. Decide what size images you need, or how much you need to zoom. Are these sources present in all available bands in J band and longer? If not, which bands have this source? You will need to change the color stretch, at least. Are any bands saturated? Bonus: find the name of any counterparts in particular for Spitzer SEIP, but also any other bands in which you can find the counterpart.
+Call them up in whatever FITS viewer works for you. Decide what size images you need, or how much you need to zoom. Are these sources present in all available bands in J band and longer? If not, which bands have this source? You will need to change the color stretch, at least. Are any bands saturated? Bonus: find the name of any counterparts in particular for Spitzer SEIP, but also any other bands in which you can find the counterpart. Double-bonus: how far offset from this position are these counterparts?
 For this location:
 *16:27:28.061,-24:39:30.92
-How many sources are there? Are these sources present in all available bands in J band and longer? If not, which bands have this source? Are any saturated? Bonus: find the name of the Spitzer components (HARD) and any Herschel counterparts.
+How many sources are there? Are these sources present in all available bands in J band and longer? If not, which bands have this source? Are any saturated? Bonus: find the name of the Spitzer components (HARD) and any Herschel counterparts. Double-bonus: how far offset from this position are these counterparts?
 =Pulling it all together=