| 其他摘要 | Objects and structures of different scales in the universe, such as planets, stellar, nebulae, galaxies and the whole universe, are researched in radio astronomy. In order to study the formation and evolution of stars before the zero-age main sequence, the molecular and atomic lines can be used as probes to observe at radio bands. Theoretical research requires a reasonable analysis of reliable observational data. By processing the observation data of H and He radio recombination lines in W51M, and utilizing the profile and broadening width in the spectrum, the electron temperature of the HII region is calculated to be around 7400 K and the turbulence velocity to be 13.767 km s-1, which is consistent with the previous studies. Moreover, in the comparison of relative flux calibration and spectral line broadening calculation, it is found that the observation method and the observation equipment may have impacts on the reliability of the data, especially on the frequency, the antenna temperature and other related parameters.The 40-meter radio telescope of Yunnan Observatories, Chinese Academy of Sciences could carry out molecular spectral line observation in C band. Its terminal is DIBAS. In order to take full advantage of the advanced performance of multi-window, multi-frequency resolution of the terminal, we introduced the observation control systems BuddleJ, M&C and its data post-processing software, which are developed by the team of Shanghai Astronomical Observatory, Chinese Academy of Sciences and obtain Fits files that can be used in Gildas Class. The first systematic observation of methanol, formaldehyde and large carbon and nitrogen chain molecules using this telescope proves that the telescope system has good performance and has the basic capacity to observe molecular spectral lines. Through further analysis, it is found that the C-band of 40-meter radio telescope is seriously interfered by radio frequency, resulting in the failure of spectral line observation in the range of 4~6 GHz. Based on current observation data, the telescope may detect molecular lines with flux densities higher than 158 mJy.In the future, the frequency resolution and the stability of the equipment are required when the spatial resolution of the telescope is concerned. Through the ratio correction method commonly used in digital signal processing, frequency correction is carried out on the discrete spectrum with frequencies of 80.0 MHz, 141.8 MHz and 270.8 MHz and the frequency resolution are improved to be 7.5 Hz/channel. Moreover, the method can be useful in checking the stability and system deviation of the local oscillator in the sampling equipment and terminal. Although the study is only applicable to single peak spectral lines in astronomical observation and is not applicable to multi-peak spectrum, it is of certain significance to the spectrum correction in the radio astronomy observations.Different from the common single point observation, the mapping observation is suitable for the extended source. Through OTF technique, single dish can generate mapping results as aperture synthesis and VLBI. The key of using the technique is the spatial sampling within the beam width to meet the Nyquist sampling theorem. After the combination of antenna, receiver, data terminal and observation requirements, the celestial sphere coordinate array is generated and sent to the coordinate conversion program according to the time series. Then the azimuth and elevation are generated and the pointing calibration is made. Utilizing this method, one can realize the separation of the outline and the antenna control program. To prove it, the observation region of the OTF simulation is set to 30‘ * 30‘, and the operation time is about 30 minutes by considering the general observation settings and the actual preparation time, which is consistent with the published papers. |
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