Matching to Spitzer and Weeding the SEDs

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Revision as of 17:32, 10 November 2011 by Rebull (talk | contribs) (→‎BRC 34)
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This page follows the same conceptual structure as Working with the BRCs (specifically steps 6 through at least 11) but reflects the most recent work in Fall 2011.

Matching known to Spitzer

In Identification of Previously Known Objects on Candidate List (and several earlier pages), we established the complete list of previously-known YSOs.

Now, we have, independently, done the Spitzer data reduction. We need to compare this catalog of known sources with the catalog from the Spitzer data reduction (which also includes 2MASS).

When I do this, sources off the edge of the Spitzer maps will not have a match, because they have no Spitzer data. Some sources will have only I1/I3 data, and some will have only I2/I4 data. (Do you remember why?) Some sources in BRC 27 we have already identified as likely very interesting sources, but because they are embedded in bright, extended nebulosity, we are going to have a hard time finding an automatic match to those sources.

Here is what I get for all of the matches to the set of previously known sources in BRC 27: File:Litsrcs+spitzer-brc27-0916-lmr.txt CAUTION: this is JUST the KNOWN sources. See next step. (also, NB: this file has optical through M24 data.)

We need to do this for BRC34 too, but this is easier because there are only two previously known sources in the literature, with no optical photometry. And, moreover, one of the two previously known sources does not appear to have a match within the Spitzer catalog. It is probably an error in the original Ogura paper, and we may never know what they were looking at originally. File:Litsrcs+spitzer-brc34-1109-lmr.txt CAUTION: this is JUST the ONE KNOWN source, and it has NO OPTICAL. See next step.

Finding IR Excess sources

In Working with the BRCs, we talked about selecting sources that appeared to have colors like young stars, e.g., objects that survive the Gutermuth selection process. I gave you a catalog of these objects on the DVD in July, for both BRC 27 and BRC 34.

All the sources in which we are interested (for now)

Recall that:

  • There will be objects with IR excesses we discover as YSO candidates,
  • there will be objects with IR excesses we REdiscover as YSO candidates that someone else identified first, and
  • there will be objects someone else identified as YSO candidates that we find to not have IR excesses.

So, we need to create one file that has all of these items in one place for both BRC 27 and BRC 34.

BRC27

For BRC27, this is that file, as of right now: File:New+known-brc27-0916-lmr.txt IMPORTANT NOTES AND CAUTIONS ABOUT THIS FILE:

  • NB: this file has mags and fluxes for all available bands, optical through M24. Did I do the flux/mag conversion correctly?
  • NB: this file has all previously identified names listed
  • NB: this file has a column, "whyhere", which indicates why this object is included in this file. If it says "IRx", it survived the Gutermuth test. If it says "PrevKn", it is a previously known source. If it says "IRx+PrevKn", it is BOTH a survivor and a known object.
  • CAUTION: See the caveats about the objects embedded in bright nebulosity above. Those objects indeed do not have counterparts here, and we will have to pursue those separately, manually.

BRC34

What about for BRC 34? This is that file, backdated to the state of things as of the end of September, prior to any SED weeding: File:New+known-brc34-0916-lmr.txt Same caveats as for the BRC 27 file.

Making and weeding the SEDs, part 1

The next step is to make the SEDs and look critically at each one, going back to images and checking photometry (again) where it needs help, for both BRC 27 and BRC 34. Based on this, we WILL drop sources off the 'interesting' list to create a 'final' list. We will have to do this again when we get optical data for these sources from Haleakala.

Notes on SEDs from BRC27 - a sort of impromptu ad hoc to-do list is at the bottom of that page as well.

Notes on SEDs from BRC34

Checking the photometry

After going through and assessing those SEDs, we needed to check on the photometry for many sources.

BRC27


BRC34

  • re-checked IRAC, MIPS photometry pending.
  • discovered bright source in the middle was missing off our list. see Notes on SEDs from BRC34 for more details.

redone catalogs for both clouds, with best, final photometry PENDING

Getting optical data incorporated

BRC Optical Ground-Based Follow-Up has the backstory on this.

BRC 34

BRC 34 data were taken Oct 22.

Russ' page on Haleakala data reduction

File:New+known+opt-brc34-1110-lmr.txt - catalog of optical through MIPS70 for BRC34, including the 'new' source added. BIG CAUTIONS THAT GO WITH THIS FILE:

  • SOME LIMITS INCLUDED IN HERE, and not indicated in the header. the limits appear in front of the flux density measurement. If there is a "<" then the true measurement of this source is somewhere below that number, e.g., we did not detect it in that band. NOTE THAT the sense of the limits is reversed. a undetected object will have a true flux density less than the cited number in microJanskys, but a true magnitude greater then a cited number in magnitudes. As such, the limits are only given in the correct sense for the flux densities, and as such only in front of the flux density measurements, but are meant to be (properly) applied to the rest of the measurements for that band.
  • Spitzer photometry still to be checked and refined, so still original Spitzer measurements in here.
  • There is a MIPS-70 measurement for one object here, which I don't think you've done before. See Central wavelengths and zero points for the information you need for 70 um.
  • no WISE data released in this region yet (unlike BRC27), so no WISE columns here.
  • no literature optical available (unlike BRC27), so optical data starts at Haleakala data (r,i).
  • All the mags are Vega-based magnitudes, except for the Sloan bands, which are AB mags! See Central wavelengths and zero points for the cautions associated with conversion of these magnitudes to flux densities.
  • Objects we are very likely going to drop are indicated in the 'whyhere' column.

File:New+known+opt-brc34-1110-lmrSEDs.pdf is the file of the SEDs that go with this. asterisks=optical (Haleakala), diamonds=2MASS, circles=IRAC, squares=MIPS. Downward pointing arrows are limits.


Catalogs of our best, final data merged with new optical data PENDING

Making and reassessing the SEDs, part 2

Now that we have new, hopefully improved Spitzer photometry, and optical data from Haleakala is coming in, we need to make new SEDs including these new/improved points, and reassess the SEDs.

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