Yingjie Jing, Jie Wang, Chen Xu, Ziming Liu, Qingze Chen, Tiantian Liang, Jinlong Xu, Yixian Cao, Jing Wang, Huijie Hu, Chuan-Peng Zhang, Qi Guo, Liang Gao, Mei Ai, Hengqian Gan, Xuyang Gao, Jinlin Han, Ligang Hou, Zhipeng Hou, Peng Jiang, Xu Kong, Fujia Li, Zerui Liu, Li Shao, Hengxing Pan, Jun Pan, Lei Qian, Jinghai Sun, Ningyu Tang, Qingliang Yang, Bo Zhang, Zhiyu Zhang, Ming Zhu
{"title":"HiFAST: An Hi data calibration and imaging pipeline for FAST","authors":"Yingjie Jing, Jie Wang, Chen Xu, Ziming Liu, Qingze Chen, Tiantian Liang, Jinlong Xu, Yixian Cao, Jing Wang, Huijie Hu, Chuan-Peng Zhang, Qi Guo, Liang Gao, Mei Ai, Hengqian Gan, Xuyang Gao, Jinlin Han, Ligang Hou, Zhipeng Hou, Peng Jiang, Xu Kong, Fujia Li, Zerui Liu, Li Shao, Hengxing Pan, Jun Pan, Lei Qian, Jinghai Sun, Ningyu Tang, Qingliang Yang, Bo Zhang, Zhiyu Zhang, Ming Zhu","doi":"10.1007/s11433-023-2333-8","DOIUrl":null,"url":null,"abstract":"<p>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 (H<span>i</span>) in the universe. We present HiFAST (https://hifast.readthedocs.io), a dedicated, modular, and self-contained calibration and imaging pipeline for processing the H<span>i</span> 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 root-mean-square (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, <i>S</i><sub>int</sub>, 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 (<i>S</i><sub>int</sub> > 2.5 Jy km s<sup>−1</sup>) 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 H<span>i</span> in the universe.</p>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":null,"pages":null},"PeriodicalIF":6.4000,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Science China Physics, Mechanics & Astronomy","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1007/s11433-023-2333-8","RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"PHYSICS, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
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 root-mean-square (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, Sint, 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 (Sint > 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.
期刊介绍:
Science China Physics, Mechanics & Astronomy, an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China, and published by Science China Press, is committed to publishing high-quality, original results in both basic and applied research.
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