Subjects: Astronomy >> Astrophysical processes submitted time 2023-10-20 Cooperative journals: 《天文研究与技术》
Abstract： In order to explore the differences in the applications of Astrometry.net and SCAMP in astrometric calibration as well as the differences in the calibration results obtained by running them in different processes, we first introduce the working principles of the two suits of software, and then do astrometric calibration to 100 images from the ZTF survey in 4 difference processes, taking Gaia DR2 catalog as the reference catalog. The calibration results including those given by ZTF itself are compared in terms of total time consuming, catalog matching, and coordinate RMS deviation. The results show that Astrometry.net can quickly calculate rough linear calibration results, while SCAMP can quickly perform distortion correction based on the former. The combined calibration process averagely takes only 1 second, and the average right ascension and declination RMS deviations are less than 70 milliarcseconds, which is better than the calibration result only using Astrometry.net. Therefore, using Astrometry. net and SCAMP in combination can achieve faster and more accurate astrometric calibration, which may be applied to data reduction of time-domain projects nowadays.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-06-07 Cooperative journals: 《天文学进展》
Abstract： Very high energy(VHE) γ-ray are considered as the best “messengers” to study the extreme Universe and its physical processes because their production mechanisms are closely related to the particles interaction and the transmission process are not influenced by the star magnetic field. The window of VHE γ-ray was opened only in 1989 by the Whipple collaboration, reporting the observation of TeV γ-ray from the Crab nebula. After a slow start, this new field of research is now rapidly expanding with the discovery of more than 200 VHE γ-ray emitting sources. Due to the limitation of effective area, space experiments can only detect γ-ray with en#2;ergy below TeV directly, the higher energy γ-ray can only be detected indirectly by ground experiments. Imaging Atmospheric Cherenkov Telescope (IACT) array is one of the key detection technology of ground-based VHE γ-ray astronomical observation and widely used in the existing and planned γ-ray ground exploration because of the most sensitive view of the very high energy γ-ray sky (50 GeV ― 20 TeV), excellent γ/p discrimination ability, coupled with relatively good angular and spectral resolution, to some extent the achieve#2;ment of ground-based VHE γ-ray astronomical observation results are closely related to the developments of IACT. The potential of atmospheric Cherenkov telescopes for γ-ray astronomy was first ex#2;plored by Jelley and Galbraith in the 1950s, the key technology image of the Cherenkov emission from air showers and stereo observation technology made important breakthroughs in the late 1980s and 1990s, and gradually developed and matured at the beginning of this century. We summarized and prospected the developments and evolutions of atmospheric Cherenkov telescope, introduced the status of VHE γ-ray detection, the principle of atmo#2;spheric Cherenkov telescope, the development, evolution and key breakthroughs of the three generation Cherenkov telescope technology, the main IACT arrays in working and some of their work highlights, compared the advantages of different ground-based detection devices. Finally, the development of the next generation IACT technology is briefly prospected.
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