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.

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):
(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 Four: watch the (13min) Catalog Cross-matching video, which talks about cross-matching and shows how to do cross-matching using Astropy routines.

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:

Step Six: Make a cluster color magnitude diagram (CMD)

Remember, when plotting a cluster CMD, you want g-r color on the y-axis and r magnitude on the x-axis, scaled like this:
plt.xlim([13,24])
plt.ylim([-1,2])