Downloading Chandra catalogs and Crossmatching to SDSS objects
Step One: you should try and install astroquery
on your computer. Just type the following into a terminal window
depending on how your python is installed (I think most of you use
anaconda, but here are instructions for both anaconda and pip):
If you can't install it, don't panic, I'll give workaround
instructions in a minute for those who cant get it installed.
- via anaconda: conda install -c astropy
- via pip: pip install --pre astroquery
Step Two: load Vizier (https://vizier.u-strasbg.fr/viz-bin/VizieR)
into your browser and watch the (13min) Introduction
to Vizier video, which shows how the Vizier catalog archive
works. By having Vizier loaded in your browser while you watch, you
can actually try some of the stuff shown in the video.
Step Three: watch the (14min) Downloading
Chandra Data video, which talks about the Chandra data we will
be getting, and how to download/read it using the astroquery
routines. (Also, it might not hurt to review the Project Intro notes
(from March 18) to remind you about how the Chandra data fits in to
the AGN search.)
If you can't get astroquery installed,
you can download the Chandra datafiles here (they are small):
Step Four: watch the (13min) Catalog
Cross-matching video, which talks about cross-matching and
shows how to do cross-matching using Astropy routines.
(But it's best if you do the download via astroquery, if you can.
My hope is that we'll do more astroquerying down the line....)
Step Five: use the ChandraCrossmatch.ipynb
notebook to download and crossmatch the Chandra data with the SDSS
data for Abell 2065. After doing the download/crossmatch, try and
make the following plots:
- log10(F90b) vs S/N: does this plot make sense?
- HRhs vs log10(F90b): which objects are most likely to be AGN?
- r0 vs SDSS-Chandra crossmatch separation: how would we decide
what would be a good match?
Step Six: Make a cluster color magnitude diagram (CMD)
- First, make a color magnitude diagram just from the SDSS data
showing all resolved sources (galaxies) projected within 1 Mpc
of the cluster center. (This is actually what we looked at in
Monday's zoom meeting, so you probably already have done this)
- On this plot, overlay all X-ray detected sources, using the
SDSS properties of their matched SDSS source. Which ones are
good candidates to be part of the cluster? Which ones probably
aren't in the cluster?
Remember, when plotting a cluster CMD, you want g-r
color on the y-axis and r magnitude on the x-axis, scaled like