Gutermuth color selection - Revision history

Rebull: /* The Gutermuth method, broken down */

2015-04-20T20:14:01Z

The Gutermuth method, broken down

Rebull at 18:45, 16 July 2012

2012-07-16T18:45:40Z

Rebull: /* The Koenig method, broken down */

2012-05-23T22:10:58Z

The Koenig method, broken down

Rebull at 00:20, 23 May 2012

2012-05-23T00:20:41Z

Rebull at 00:15, 23 May 2012

2012-05-23T00:15:24Z

Rebull: /* Complicated equations can spell out simple things */

2012-02-15T18:44:57Z

Complicated equations can spell out simple things

Rebull at 01:01, 24 January 2012

2012-01-24T01:01:12Z

Rebull: /* Complicated equations can spell out simple things */

2012-01-24T01:00:47Z

Complicated equations can spell out simple things

Rebull at 01:00, 24 January 2012

2012-01-24T01:00:07Z

Rebull: /* Introduction */

2012-01-24T00:59:02Z

Introduction

@@ Line 51: / Line 51: @@
 =The Gutermuth method, broken down=
-See [[media:gutermuth-appa.pdf| Gutermuth et al. 2009, Appendix A]] for the absolutely complete discussion, justification, etc.  Technically, we should deredden the photometry for some of these steps, but we don’t have enough information to to that, and it should not matter too much for the stars we are working with.
+See [[media:gutermuth-appa.pdf| Gutermuth et al. 2009, Appendix A]] for the absolutely complete discussion, justification, etc.  Technically, we should deredden the photometry for some of these steps, but we often don’t have enough information to do that, and it should not matter too much for the stars we are working with.
 [[media:gutersumm.pdf|Summary of the color steps (pdf)]]

@@ Line 59: / Line 59: @@
 =The Koenig method, broken down=
-The Koenig method is the same idea as Gutermuth, but for different bands. [[file:koenigapp.pdf|Koenig et al. 2012 appendix]]
+The Koenig method is the same idea as Gutermuth, but for different bands. [[file:koenigapp.pdf|Koenig et al. 2012 appendix]] - sorry, but to get this file onto the wiki server, i had to decrease its resolution almost to illegibility. if you want a full-res copy of the file, go get the original article (Koenig et al. 2012 ApJ, 744, 130) or let me know and I'll email it to you.
 =Real life situation=
 [[Taurus catalog]] has a catalog of legitimate young stars. Where do these objects fall with respect to either the Gutermuth or Koenig colors? Which ones would be retrieved or lost by these color selections?

@@ Line 58: / Line 58: @@
 =The Koenig method, broken down=
-Coming soon... same idea, different bands ...
 =Real life situation=
 [[Taurus catalog]] has a catalog of legitimate young stars. Where do these objects fall with respect to either the Gutermuth or Koenig colors? Which ones would be retrieved or lost by these color selections?

← Older revision		Revision as of 00:20, 23 May 2012
Line 59:		Line 59:
	=The Koenig method, broken down=		=The Koenig method, broken down=
	Coming soon... same idea, different bands ...		Coming soon... same idea, different bands ...
		+
		+	=Real life situation=
		+	[[Taurus catalog]] has a catalog of legitimate young stars. Where do these objects fall with respect to either the Gutermuth or Koenig colors? Which ones would be retrieved or lost by these color selections?

← Older revision		Revision as of 00:15, 23 May 2012
Line 58:		Line 58:

	=The Koenig method, broken down=		=The Koenig method, broken down=
−	Coming soon...	+	Coming soon... same idea, different bands ...

@@ Line 47: / Line 47: @@
 =Complicated equations can spell out simple things=
-See [http://www.npr.org/blogs/krulwich/2012/01/10/144991340/don-t-make-me-do-this-the-equations-screamed here], and be sure to click on the complicated equations to see what they describe.  The Gutermuth (or for that matter, Koenig) method has similar complicated sets of equations, but they are just describing line segments in various color-color and color-magnitude spaces. Sit down and work through a few, even with a pencil and paper if you don't want to use Excel. You'll see, it's not so bad; it just ''looks'' bad.
+See [http://www.npr.org/blogs/krulwich/2012/01/10/144991340/don-t-make-me-do-this-the-equations-screamed here], and be sure to click on the complicated equations to see what they describe. Or, perhaps try googling "sqrt(cos(x))*cos(300x)+sqrt(abs(x))-0.7)*(4-x*x)^0.01, sqrt(6-x^2), -sqrt(6-x^2) from -4.5 to 4.5" (without the quotes around it).   The Gutermuth (or for that matter, Koenig) method has similar complicated sets of equations, but they are just describing line segments in various color-color and color-magnitude spaces. Sit down and work through a few, even with a pencil and paper if you don't want to use Excel. You'll see, it's not so bad; it just ''looks'' bad.
 =The Gutermuth method, broken down=

← Older revision		Revision as of 01:01, 24 January 2012
Line 56:		Line 56:

	We can easily do the Gutermuth method up to slide 26. This provides an IRAC-based selection. We cannot deredden (we don’t have enough information), so we can’t do his JHK steps. We need to look for things that are MIPS-only; for CG4/SA101, they just fell out of the IRAC selection. We then take that initial, automatic cut and produce a short list of objects. Then we need to look at each and every one of those objects in the Spitzer bands and any other bands we can find. We then can drop computer glitches of one sort or another (duplicate sources), and we can identify any sources that are actually resolved background galaxies. Then we need to construct and examine the SED for each one, and assess them all individually for quality (like Gutermuth does too).		We can easily do the Gutermuth method up to slide 26. This provides an IRAC-based selection. We cannot deredden (we don’t have enough information), so we can’t do his JHK steps. We need to look for things that are MIPS-only; for CG4/SA101, they just fell out of the IRAC selection. We then take that initial, automatic cut and produce a short list of objects. Then we need to look at each and every one of those objects in the Spitzer bands and any other bands we can find. We then can drop computer glitches of one sort or another (duplicate sources), and we can identify any sources that are actually resolved background galaxies. Then we need to construct and examine the SED for each one, and assess them all individually for quality (like Gutermuth does too).
		+
		+	=The Koenig method, broken down=
		+	Coming soon...

@@ Line 43: / Line 43: @@
 Now... For each combination, can compare colors for each object (e.g., make a plot). For each object, note properties of that object in that comparison. Then, have a big table, one entry per object, with properties of each object in each combination. You can then make an educated guess, based on properties in all available bands, which are the blue peanut M&Ms.
-This is what we need to do using Spitzer colors for the young star candidates.  We measure the properties of each object in all available bands.  We make plots and compare them in many different color-color spaces. (You can do this manually, or let the computer do the comparison.) We make educated guesses as to which objects were likely YSOs or contaminants in each space, keeping track of which objects were which and which had which properties. (This bookkeeping should all be done within the computer.)
+This is what we need to do using Spitzer or WISE colors for the young star candidates.  We measure the properties of each object in all available bands.  We make plots and compare them in many different color-color spaces. (You can do this manually, or let the computer do the comparison.) We make educated guesses as to which objects were likely YSOs or contaminants in each space, keeping track of which objects were which and which had which properties. (For your own sanity, this bookkeeping should all be done within the computer.)
 =Complicated equations can spell out simple things=

@@ Line 5: / Line 5: @@
 No color cuts can perform this task flawlessly, though many have been discussed in the literature in the context of Spitzer observations (e.g., Allen et al. 2004, Padgett et al. 2008b, Rebull et al. 2007, Harvey et al. 2007, Gutermuth et al. 2008, 2009, Rebull et al. 2010, 2011) and now WISE too (Koenig et al. 2011).
-Right after Spitzer started, there were some simple color cuts implemented to try and find these objects. There are some examples on the [[Color-Magnitude and Color-Color plots]] page.  These are simple to explain and implement and visualize.  However, by 2008-2009, the community had started to recognize that this was actually a more complex problem, requiring cuts in more than one space at a time. The basic approach of Gutermuth et al. (see [[media:gutermuth-appa.pdf| Gutermuth et al. 2009, Appendix A]]) is the easiest way to impose a series of cuts in several different color-color and color-magnitude spaces all at once (by computer) to get a first guess at a list of young stars. Here we now discuss these cuts in more detail.
+Right after Spitzer started, there were some simple color cuts implemented to try and find these objects. There are some examples on the [[Color-Magnitude and Color-Color plots]] page.  These are simple to explain and implement and visualize.  However, by 2008-2009, the community had started to recognize that this was actually a more complex problem, requiring cuts in more than one space at a time. The basic approach of Gutermuth et al. (see [[media:gutermuth-appa.pdf| Gutermuth et al. 2009, Appendix A]]) is the easiest way to impose a series of cuts in several different color-color and color-magnitude spaces all at once (by computer) to get a first guess at a list of young stars. Koenig et al. (2011) extended this method to the WISE bands.  Here we now discuss this concept and these cuts in more detail.
 =Example of this concept using more familiar things=