What did luisa do?
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.
several people measured and reported fluxes at various bands. note that PA used MaxImDL, Rebull used apex/idl, and the rest used APT:
| person or group | irac1 (Jy) | irac2 (Jy) | irac3 (Jy) | irac4 (Jy) | mips1 (Jy) |
| PA group (Spuck et al.) | 0.0184 | 0.0406 | 0.0634 | 0.0771 | 1.58 |
| DeWolf & Johnson team | 0.0173 | 0.0394 | 0.06194 | 0.0793 | 1.822 |
| Shaefers | 0.01783 | 0.03963 | 0.06626 | 0.0916 | 1.9068 |
| NY group (Guastella et al.) | 0.017106 | 0.039 | 0.0625 | 0.0779 | 1.82 |
| MT Group (Dave McDonald) | 0.017193 | ||||
| MT group (Brandi, Blair, and Jacob average) | 0.0172 | 0.0389 | 0.0617 | 0.0778 | 1.636 |
| Rebull | 0.0152 | 0.0349 | 0.0600 | 0.0721 | 1.363 |
| AVERAGE | 0.0172 | 0.0388 | 0.0625 | 0.0788 | 1.675 |
| STD DEV | 0.000814 | 0.001665 | 0.001837 | 0.005570 | 0.172084 |
| fractional error | 0.047 | 0.042 | 0.029 | 0.070 | 0.102 |
the last row means that there is a 5% scatter in our measurements for irac-1 and 2, a 3% scatter in the measurements for irac-3, a 7% error in the measurements for irac-4, and a 10% error in the measurements for mips-1. these are really pretty darn good! pat yourself on the back. there is rather more scatter in mips-1 in particular than i was expecting, but this is probably because APT doesn't allow you to center up on a sub-pixel value.
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? the spreadsheet we made in june calculates several colors for you.
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? the spreadsheet we made in june makes the SED.
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).
good enough now to stop here for the AAS poster discussion on this target. NOTE THAT if you want any of the plots i made for the poster, i can make them using bigger font. just let me know.
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. russ's spreadsheet will allow us to model it as a series of blackbody curves, but i'm talking about something more sophisticated (see links on l1688 page for a start).
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.
make some multi-color images. look for very red sources in any combination of images. there aren't any boomers like in the other cloud, but i think i see some red objects anyway.
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. TONS more sources here than in the other observation, so it is easier to make this assessment. Luisa's plots of lynds981 photometry (pdf) now that there are a lot more points, the things that are red kinda stand out in these plots (the analogous plots for our other data look really silly because there are so few points).
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. look at where the objects are here that fall in the "red zone" and see how they compare to YSOs in those other plots.
here are the color selections i have most recently used in my work elsewhere to find YSOs. note that i am looking for not just red but also the brighter things (note, "brighter" does NOT mean saturated!! one of the comments on the talk page seems to imply some of you are looking for saturated objects). "Ks" = "K-short", a.k.a. the 2MASS K band measurement. the equations describe lines in the color-mag and color-color plots (try 'em! plot 'em up and see!). the color-mag and color-color spaces i used are:
- Ks vs. Ks-[24]
- [8] vs. [8]-[24]
- [4.5] vs. [4.5]-[8]
- [3.6]-[4.5] vs. [5.8]-[8] with an additional [3.6] brightness cutoff
the formulas are here: 
this color-based selection of YSOs suggests the following candidates (NOTE THAT you should refer to these by their full coordinates -- the names that are here follow IAU convention for new objects):
| name |RA |Dec | | |d |d | 205939.52+502124.2 314.914683 50.356735 205947.91+501432.3 314.949627 50.242329 210017.34+501940.4 315.072276 50.327901 210017.36+501940.3 315.072334 50.327888 210036.99+502057.6 315.154161 50.349361 210046.34+502344.9 315.193086 50.395817 210049.05+501524.5 315.204405 50.256821 210049.50+501542.9 315.206282 50.261929 210054.66+502617.0 315.227775 50.438076 210120.34+502007.7 315.334766 50.335499 210142.11+501305.4 315.425497 50.218189 210147.48+501821.9 315.447873 50.306110
a few of these are found in more than 1 CMD, suggesting perhaps more likely YSO? here are some sample CMDs/CCDs with these objects highlighted in red - you can see they are distinctly redder than the rest of the sample: Media:lynds981ysocandcmds.pdf
also need to look at where in space they fall:
i don't believe the photometry for those guys on the edge of the frame. (this is an irac-4 image, BTW.)
i also question the two objects that are right on top of each other - i think there is probably just one source really there that the source extractor saw as two objects.
are any of these previuosly known objects? go get literature. quanz et al. (2007, ApJ, 656, 287, also astro-ph/0610786) paper leads us to feigelson and kriss (1983, AJ, 88, 431) paper. feigelson and kriss report only names and finder charts; need to go to 2mass to extract high-quality modern coordinates. use their finder chart, a new poss image, and a new 2mass image to reconstruct which obj are which 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 ("fk" numbers correspond to numbers 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
here is all my photometry: Media:ldn981ysocand.cat.tbl. if you want my photometry for other objects (like any of the ones you all found on your own), let me know; i just didn't post the whole catalog because it would be too overwhelming.
AS ABOVE, when we measure spitzer fluxes, we get them back in uJy (or mJy or similar). the 2mass data come to us in magnitudes. 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. i did that in the file above.
go look at the CMDs and CCDs that people use to find YSOs. look above at where our objects fall in these diagrams. are they weak or strong compared to the source in our other cloud?
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 these sources. as above, watch your units. are these sources weak or strong compared to the source in our other cloud? here are my SEDs: Media:ldn981ysocandseds.pdf most of them are pretty small excess objects. this is consistent with what our eyes told us way back at the beginning - there aren't any booming red objects here.
here, one or two CMDs and/or SEDs can go into the poster.
good enough now to stop here for the AAS poster discussion on this target. NOTE THAT if you want any of the plots i made for the poster, i can make them using bigger font. just let me know.
ultimately, we want to go get follow-up optical classification spectra for these things to verify that they are really YSOs and not just background objects (or errors in the photometry).
