DATA FREQUENCY DOMAIN ANALYSIS AND TELESCOPE AUTOMATIC CONTROL: A CASE STUDY OF NEUTRAL HYDROGEN OBSERVATION EXPERIMENT

Hydrogen is the most abundant baryonic matter in the universe, with most of it existing in the form of hydrogen atoms. The hyperfine line of neutral hydrogen atoms at 21cm wavelength is a strong radio source in the sky, making it a tool to probe the distribution of cosmic baryonic matter. In this paper, we introduce the experiment of galactic neutral hydrogen line observation conducted on the 3.2m radio telescope at Sun Yat-sen University (SYSU). The dynamic spectrum is achieved from the time-domain electromagnetic signals. The signal-to-noise ratio is increased by binning the timesteps and the spectra channels in the experiment. We also introduce the observation modes of radio telescopes, and achieve automatic sky survey on the 3.2m SYSU radio telescope. Sky map of neutral hydrogen distribution in our galaxy is generated in an elective experiment. Based on the sky map, the distance between the sun and the galactic center is estimated, and the galactic rotation curve is obtained based on the redshift of the lines. This paper, combined with the previous experiment on the temporal variation of solar radio flux introduced in the first paper of this series, provide references for practical radio astronomy teaching.