选址与日冕观测组知识库

The Wumingshan mountain (Mt. WMS), located in the Grand Shangri-La area of south-west China, has been selected as one of the most potential regions for hosting China’s next-generation ground-based large telescopes. Firstly, Mt. WMS has ideal astronomical conditions for both day-time and night-time observations. Comprehensive analysis of remote and on-site long-term meteorological, geological and geographic data suggests that WMS satisfies the strict requirements for an excellent candidate site, through a series of key parameters including average seeing factor r0, sky brightness, clear-sky days, precipitable water vapor content (PWVC), refractive index structure constant, atmospheric coherence time, isoplanatic angle and meteorological information etc. Averagely, its daily seeing factor is over 10 cm and its night seeing factor is 0.9 arcsec on ground. The average wind speed is less than 5 m/s. The average normalized PWVC at unit air mass is about 2.5 mm. The average yearly sunshine duration is generally more than 2500 hours. The amount of yearly clear sky days and nights are respectively 250 d and 270 d. The median night sky brightness level is 21.8 mag arcsec-2. The atmosphere cleanliness is also excellent. Secondly, Mt. WMS possesses the necessary conditions for the establishment of high altitude observatories. Its ridge is flat and spreads over 2 km2. The large relative elevation difference in the local terrain, plus the existence of population settlements at low altitude (~ 2800 m) in the vicinity, substantially reduces the future cost for construction, settlement, and logistics. Its geological structure is stable, and there is virtually no record of geological disaster or inclement weather. The nearby counties have low population density (~5 km-2) and there have been extensive transportation networks. In October 2014, we initiated a long-term monitoring project in Mt. WMS. We have been collecting data from two monitoring sites for more than three years. Both sites are located about 4700~4800 m above the sea level. Our instruments mainly include the solar and stellar Differential Image Motion Monitors, the Sky Brightness Monitors, the PWVC monitors, the Atmospheric Temperature Fluctuation Monitors, the Multi-wavelength Solar Photometers and robot meterological stations, and so on. There have been a lot of activities within the ASO-G (i.e., CGST and large coronagraph) sites’ study since our last reports.1, 2 In this paper, we introduce the daily observation, transmission, storage and analysis of the harvested data, and the overall operation, management and technical support of the monitoring platforms.