Vol 22, No 6

## Extragalactic HI Survey with FAST: First Look at the Pilot Survey Results

#### Jiangang Kang, Ming Zhu, Mei Ai, Haiyang Yu, Chun Sun

Abstract

Abstract We present the first data release of H I sources extracted from a pilot extragalactic survey using the Five-hundredmeter Aperture Spherical radio Telescope (FAST). We extracted sources from three-dimensional (3D) spectral data cubes datacubes to perform interactive searching and computing, yielding global parameters for each source, extending redshift ranges of H I emission up to z = 0.04. A total of 544 extragalactic H I sources has been detected by the pilot FAST H I drift scan survey covering part of the sky region in R.A. (R.A. or α) and decl. (decl. or δ) range 00h 47m < R. A. (J2000) < 23h 22m and +24° < decl. (J2000) < +43°. Of which, 528 sources are matched with optical counterparts via examination of digital optical survey databases collected from NED (http://ned. ipac.caltech.edu/Documents/Guides/Searches) and Vizier (https://vizier.u-strasbg.fr/viz-bin/VizieR-2) data center, and 449 of them have optical velocities. Furthermore, we detect 36 galaxies with H I mass $$<10^8~M_{\odot}$$, which is significant for the study of low-mass systems in the local universe. We present catalogs for all H I detections with signal-to-noise ratio (S/N) greater than 5.1. The data are classified into four categories based on their S/N and baseline qualities, which are flagged with code 1 to 4: (1) 422 sources with S/N > 6.5; (2) 61 sources with 5.1 $$\lesssim$$ S/N $$\lesssim$$ 6.5; (3) 28 sources with relatively poor baselines; (4) 33 sources that are partly masked by strong radio frequency interferences (RFIs). In addition, we find 16 H I sources that have not been matched with any counterparts in the existing galaxy catalogs. This data release can provide guidance for the future extragalactic H I survey with FAST.

Keywords

Keywords galaxies: formation – radio lines: galaxies – surveys – galaxies: distances and redshifts – radiation: dynamics – galaxies: evolution

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