The Arecibo Legacy Fast ALFA Survey: VIII. HI Source Catalog of the Anti-Virgo Region at dec = +25 deg

TL;DR

This paper presents a catalog of 541 HI sources from the ALFALFA survey in the Anti-Virgo region, including extragalactic sources and high velocity clouds, with high reliability and optical counterparts for most objects.

Contribution

It provides a new, detailed catalog of HI sources in a specific sky region, expanding previous surveys with improved detection reliability and optical matching.

Findings

541 HI sources cataloged in the Anti-Virgo region

High detection reliability (>95%) for sources with S/N > 6.5

Most extragalactic sources have optical counterparts

Abstract

We present a fourth catalog of HI sources from the Arecibo Legacy Fast ALFA (ALFALFA) Survey. We report 541 detections over 136 deg2, within the region of the sky having 22h < R.A. < 03h and 24 deg < Dec. < 26 deg . This complements a previous catalog in the region 26 deg < Dec. < 28 deg (Saintonge et al. 2008). We present here the detections falling into three classes: (a) extragalactic sources with S/N > 6.5, where the reliability of the catalog is better than 95%; (b) extragalactic sources 5.0 < S/N < 6.5 and a previously measured optical redshift that corroborates our detection; or (c) High Velocity Clouds (HVCs), or subcomponents of such clouds, in the periphery of the Milky Way. Of the 541 objects presented here, 90 are associated with High Velocity Clouds, while the remaining 451 are identified as extragalactic objects. Optical counterparts have been matched with all but one of the extragalactic objects.