FAST Ultra-Deep Survey: Data Release for FUDS0

We have used the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to conduct a blind ultradeep survey for neutral hydrogen (H i). We present the complete results from the first of six fields (FUDS0). These observations of 95 hr allowed us to achieve a high-sensitivity (∼50 μJy beam−1) and a high-frequency resolution (22.9 kHz) over an area of 0.72 deg2. We detected 128 galaxies in H i distributed over the redshift range of 0 < z < 0.4, with H i masses in the range of , and three faint high-velocity clouds, with a peak column density of NH i ≤ 3.1 × 1017 cm−2. Of the galaxies, 95 are new detections and six have z > 0.38, where no unlensed H i emission has previously been directly detected. Estimates of completeness and reliability are presented for the catalog. The consistency of continuum and H i flux estimates with the NRAO VLA Sky Survey and the Arecibo Ultra-Deep Survey, respectively, confirms the accuracy of the calibration method and data reduction pipeline developed for the full FAST Ultra-Deep Survey.