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, S_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_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.

500米口径球面射电望远镜（FAST）拥有最大的口径和19束L波段接收器，使其成为研究宇宙中中性氢原子气体（H i ）的强大工具。我们推出了 HiFAST (https://hifast.readthedocs.io)，这是一种专用的、模块化的、独立的校准和成像管道，用于处理 FAST 的 Hi数据。该流程包括频率相关噪声二极管校准、基线拟合、使用基于 FFT 的方法去除驻波、通量密度校准、杂散辐射校正以及网格化以生成数据立方体。这些模块可以根据需要进行组合，以处理来自大多数 FAST 观测模式的数据：跟踪、漂移扫描、动态测绘及其大多数变体。使用 HiFAST，所有 19 个光束的校准光谱的均方根 (RMS) 噪声仅略高于理论预期 (∼5%)。扩展源 M33 和点源的结果与阿雷西博的结果一致。 M33的矩图（0、1和2）与阿雷西博星系环境调查（AGES）的结果非常吻合，分数差异小于10%。对于来自 Arecibo Legacy Fast ALFA (ALFALFA) 调查的 221 个信噪比 S/N > 10 源的常见样本，两个数据集之间积分通量密度S _int的分数差平均值为约0.005%，离散度为15.4%。进一步检查23个光源的7个观测值的积分通量密度表明，光源与发光物体（S _int > 2.5 Jy km s ^-1）的通量密度方差小于5%。我们的测试表明，FAST 望远镜以及高效、精确且用户友好的 HiFAST 管道将在宇宙中H i的研究中产生许多重要的科学发现。