Measuring the Mass of the Pisces-Perseus Supercluster with the APPSS Survey

The Arecibo Pisces-Perseus Supercluster Survey (APPSS) is a project to determine the mass of the Pisces-Perseus Supercluster by measuring the effect of the supercluster’s gravity on the velocities of galaxies near the supercluster. The velocities of the galaxies are determined using observations of the 21-cm line emitted by atomic hydrogen (HI), obtained at the Arecibo Observatory in Puerto Rico.  A galaxy's velocity has two components, one due to the effects of the expansion of the Universe, the Hubble velocity, and one due to the local gravity from the supercluster, or the “peculiar” velocity. I present reduction and analysis of APPSS HI spectral data of 177 targets in a slice at declination 29 degrees to obtain velocities and identify members of the supercluster. 49% of the 177 target galaxies were detected. Of these detections, 66% are possible members of the Pisces-Perseus Supercluster. Optical observations obtained from public archives are used to determine the distance of the galaxies to remove the Hubble velocity, providing the peculiar velocity for each galaxy. Analysis of the final sample of 2000 galaxies will be used to determine the supercluster’s mass.