帕米尔高原慕士塔格址点天文观测条件研究

As one of the three high-altitude sites of ongoing site-testing for China's "Large Optical/ infrared Telescope Project”, Muztagh Ata site has been monitored since the beginning of 2017; and the observation work was carried out smoothly. The observation shows that the site present good seeing and possible low near ground turbulence layer, which show features of a high quality site. In addition, Muztagh Ata site is located in the far west of China, has a unique geographical position in longitude for time-domain observing equipment layout. So, it is of great significance to study the site’s astronomical observing conditions in depth. Aiming at the comprehensive and reliable evaluation of the astronomical observing conditions of Muztagh Ata site, three researches are set up in this project. (1) Statistical analysis and study of astro-cliamte and meteorological parameters of the site, (2) Investigating the site's characteristics of seeing and ground layer turbulence, and (3) the study of the site’s environment for astronomical photometry. It is an important research work for a site-testing to observe and accumulate the reliable astro-cliamte and meteorological data of candidate site for many years, and give the results of statistical analysis and compare them with that of other existing sites. Furthermore, the characteristics of the near ground turbulence and the environment for astronomical photometry are two important aspects need to be considered in order to determine the site’s quality; therefore, it is also necessary to carry out the research on them in depth. There is a batch of site-testing equipment running at Muztagh Ata site, which can guarantee the acquisition of necessary data for this project.

作为我国正在开展的“大型光学/红外望远镜项目”选址监测的三个高原址点之一，帕米尔高原慕士塔格选址点2017年初投入定点监测，观测工作平稳进行。观测显示该址点视宁度好、近地面逆温层低，表现出良好台址的特征；另外，该址点地处我国最西部，在时域天文观测布局中具有独特的地理经度位置；所以，对该点天文观测条件开展深入研究有重要意义。以全面可靠的评价慕士塔格址点天文观测条件为目标，本项目设置三个研究内容：（1）址点天文气象参数的统计分析研究；（2）址点视宁度与近地层湍流特性的研究；（3）址点测光环境研究。观测积累多年可靠的台址监测数据，给出统计分析结果，并与已有台址比对，是选址工作重要的研究内容；而近地面湍流特征和测光环境是决定台址质量的两个重要方面，也是台址综合评价的重要内容，深入研究是必要的。慕士塔格址点正在运行着多台选址观测设备，可保证研究数据的获取。开展本项目的研究条件具备。

随着地基光学望远镜口径的不断增大，光学天文台址的观测条件已经成为决定这些大口径光学望远镜能否发挥极限设计性能的关键因素，我国亟需优良的址点来运行新一代 10 米级光学/红外望远镜。以全面可靠的评价慕士塔格址点天文观测条件为目标，本课题设定主要的研究内容是：（1）址点天文气象参数的统计分析研究；（2）址点视宁度与近地层湍流特性的研究；（3）址点测光环境研究。在项目执行期内，本课题在慕士塔格台址开展了长期的台址条件数据监测，并深入分析了数据统计结果，得到的主要结论有：慕士塔格台址夜间温度中值为­6.2℃，夜间相对湿度中值为 49%；夜间风速中值为 5.5m/s，址点主风向为西南风；台址可观测时间比例为65%；无月夜的夜天光年中值为21.74 mag/arcsec2；11 米高度视宁度中值为0.82arcsec；年晴天PWV中值为2.3mm。本课题从多个角度系统的评估了慕士塔格台址的光学观测条件质量，为进一步深入挖掘帕米尔高原天文台址资源奠定了基础。