Abell 1656: The Coma Cluster of Galaxies

This tutorial uses the advanced VO functionalities of Aladin (interactive sky atlas), TOPCAT (tools to work on catalogs) and Cassis (interactive spectrum analyzer) to study interactively the Coma cluster of galaxies. The user can visualize the Coma cluster of galaxies and build a subset of these galaxies with Aladin. With TOPCAT, they can analyze this subset. Finally, they can study an HST power spectrum with Cassis. (If needed the complementary Jupyter notebook can be downloaded at http://www.euro-vo.org/sites/default/files/documents/tutorial_abel1656-p....)

Goal of this tutorial:
•Examine the Coma cluster of galaxies (Abell 1656) using VO data and tools in order to performa quick evaluation of the mean redshift and velocity dispersion of the cluster.
•Use redshifts and photometry (Petrosian r magnitude) of the SDSS survey and then add redshiftsof the CAIRNS survey (Rines et al. 2003) in order to improve the completeness of the redshiftsample.
•Look for hydrogen lines in HST spectra in the direction of this cluster and check whether thelines are consistent with foreground or with galaxy velocities.The software packages we require to tackle these tasks are Aladin, TOPCATand CASSIS.