HiFAST: an HI data calibration and imaging pipeline for FAST

Abstract

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has the largest aperture and a 19-beam L-band receiver, making it powerful for investigating the neutral hydrogen atomic gas (HI) in the universe. We present HiFAST (https://hifast.readthedocs.io), a dedicated, modular, and self-contained calibration and imaging pipeline for processing the HI data of FAST. The pipeline consists of frequency-dependent noise diode calibration, baseline fitting, standing wave removal using an FFT-based method, flux density calibration, stray radiation correction, and gridding to produce data cubes. These modules can be combined as needed to process the data from most FAST observation modes: tracking, drift scanning, On-The-Fly mapping, and most of their variants. With HiFAST, the RMS noises of the calibrated spectra from all 19 beams were only slightly (~ 5%) higher than the theoretical expectation. The results for the extended source M33 and the point sources are consistent with the results from Arecibo. The moment maps (0,1 and 2) of M33 agree well with the results from the Arecibo Galaxy Environment Survey (AGES) with a fractional difference of less than 10%. For a common sample of 221 sources with signal-to-noise ratio S/N >10 from the Arecibo Legacy Fast ALFA (ALFALFA) survey, the mean value of fractional difference in the integrated flux density, $S_{\mathrm{int}}$, between the two datasets is approximately 0.005 %, with a dispersion of 15.4%. Further checks on the integrated flux density of 23 sources with seven observations indicate that the variance in the flux density of the source with luminous objects ($S_{\mathrm{int}}$ $>2.5$ Jy km s${}^{-1}$) is less than 5%. Our tests suggest that the FAST telescope, with the efficient, precise, and user-friendly pipeline HiFAST, will yield numerous significant scientific findings in the investigation of the HI in the universe.

Accepted by SCPMA. 21 pages, 14 figures. The pipeline is accessible at https://hifast.readthedocs.io

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Cited by in corpus (16)

• HiFAST : An HI Data Calibration and Imaging Pipeline for FAST II. Flux Density Calibration
• HiFAST: An HI Data Calibration and Imaging Pipeline for FAST III. Standing Wave Removal
• Beam Measurements of Full Stokes Parameters for the FAST L-band 19-beam Receiver
• The FAST HI 21-cm absorption blind survey. II. -- Statistic Exploration for Associated and Intervening systems
• FASHI: An untargeted survey of the 21 cm HI absorption galaxies with FAST
• Unveiling the nature and fate of the almost-dark cloud AGC 226178 through HI mapping
• The FAST Ursa Major supergroup HI survey (FUMaS): catalog and HI mass function
• Observation of HI around three satellite galaxies of the M31 with the FAST: Andromeda II, NGC 205, and NGC 185
• FASHI: A search for extragalactic OH megamasers with FAST
• AVID: Formation and evolution of a coalesced major merger of late-type dwarf galaxies (VCC 479) on the outskirts of the Virgo cluster
• Reinforcement Learning for Data-Driven Workflows in Radio Interferometry. I. Principal Demonstration in Calibration
• HiFAST: An HI data calibration and imaging pipeline for the FAST IV: The stray-radiation correction
• Deep neutral hydrogen observations of the early-type galaxy NGC 2768: collided by a newly discovered satellite galaxy?
• AVID: A Near-Major Post-Merger of Late-Type Dwarfs beneath a Regularly Rotating HI Disk (VCC 693)
• The FAST Hundred-Deg${}^2$ HI Deep (HD${}^2$) Survey: Early Results from the Pilot Survey
• Toward Understanding the Evolutionary Role of Star-forming Lenticular Galaxies: New HI Detections and Comparison with Quiescent S0s and Red Spirals