The Optical/Infrared Astronomical Quality of High Atacama Sites. I. Preliminary Results of Optical Seeing
The Optical/Infrared Astronomical Quality of High Atacama Sites. I. Preliminary Results of Optical Seeing
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阿塔卡马高地的光学/红外天文质量。
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
M. Swain
中科院分区：
文献类型：
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作者：
R. Giovanelli;J. Darling;M. Sarazin;Jennifer Yu;P. Harvey;C. Henderson;W. Hoffman;L. Keller;D. Barry;J. Cordes;S. Eikenberry;G. Gull;J. Harrington;J. Smith;G. Stacey;M. Swain
位于智利北部阿塔卡马沙漠的高海拔高原查南托周围地区，因其作为天文台的潜力而引起了天文学界的注意。结合高海拔和极低的大气含水量，Llano已被选为阿塔卡马大型毫米波阵列的未来地点。我们已经发起了一项运动，调查该地区在光学/红外方面的天文潜力。在此，我们报告我们的运动的一个方面，其目的是建立一个看得见的基准，作为该地区今后活动的参考。在简要介绍了该地区及其气候之后，我们描述了用0.5 μm波长的差分像动监测器进行的天文观测活动的结果。1998年5月在海拔5000米的Llano观测了7个晚上，得到的FWHM中值为1.″1。然而，视力下降到0。″7从1998年7月到2000年10月的38个夜晚，在高原（Cerro Chico）上方适度升高100米。这两种情况都不能代表该地区预期的最佳视力；这组测量结果为目前正在Cerro Chico和该地区其他感兴趣的地点同时进行的双重运行提供了参考基础。在Cerro Chico和Cerro Paranal的同时测量结果的比较表明，Cerro Chico的观测结果比Paranal的观测结果好12%。在Chajnantor地区，光学光度夜的百分比约为60%，而对天文工作有用的夜的百分比接近80%。
The region surrounding the Llano de Chajnantor, a high‐altitude plateau in the Atacama Desert in northern Chile, has caught the attention of the astronomical community for its potential as an observatory site. Combining high elevation and extremely low atmospheric water content, the Llano has been chosen as the future site of the Atacama Large Millimeter Array. We have initiated a campaign to investigate the astronomical potential of the region in the optical/infrared. Here we report on an aspect of our campaign aimed at establishing a seeing benchmark to be used as a reference for future activities in the region. After a brief description of the region and its climate, we describe the results of an astronomical seeing campaign, carried out with a Differential Image Motion Monitor that operates at 0.5 μm wavelength. The seeing at the Llano altitude of 5000 m, measured over 7 nights in 1998 May, yielded a median FWHM of 1.″1. However, the seeing decreased to 0.″7 at a modest 100 m gain above the plateau (Cerro Chico), as measured over 38 nights spread between 1998 July and 2000 October. Neither of these represents the best seeing expected in the region; the set of measurements provides a reference base for simultaneous dual runs at Cerro Chico and at other sites of interest in the region, currently underway. A comparison between simultaneous measurements at Cerro Chico and Cerro Paranal indicates that the seeing at Cerro Chico is about 12% better than that at Paranal. The percentage of optically photometric nights in the Chajnantor region is about 60%, while that of nights useful for astronomical work is near 80%.