Observing Conditions at Mount Graham: Vatican Advanced Technology Telescope UBVR Sky Surface Brightness and Seeing Measurements from 1999 through 2003
Observing Conditions at Mount Graham: Vatican Advanced Technology Telescope UBVR Sky Surface Brightness and Seeing Measurements from 1999 through 2003
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DOI：
10.1086/422929
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发表时间：
2004-06
影响因子：
3.5
通讯作者：
V. Taylor;R. Jansen;R. Windhorst
中科院分区：
文献类型：
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作者：
V. Taylor;R. Jansen;R. Windhorst
我们目前的天空表面亮度和看到格雷厄姆山，在梵蒂冈先进技术望远镜（VATT）在1999年4月至2003年12月之间的16次观测运行获得的测量。我们表明，天空表面亮度显着黑暗的光度条件下，可以是高度可变的过程中的一个单一的观察运行，以及从一个运行到下一个，无论光度。在我们的测光观测中，我们发现U、B、V和R的平均低空气质量（秒z<1.2）天空表面亮度分别为22.00、22.53、21.49和20.88等角秒−2。最暗的运行（2000年2月在U和2001年2月在BVR）的平均天空表面亮度分别为22.38、22.86、21.72和21.19等角秒−2（U、B、V和R）。有了这些结果，我们表明，在最佳条件下，格雷厄姆山可以与夏威夷和智利最黑暗的地方竞争，部分原因是图森和萨福德严格的黑暗天空条例。我们预计在太阳活动极小期（2006-2007年），格雷厄姆山的天空会比我们1999-2003年的结果更暗。在2001年夏季和秋季对望远镜进行改进后，我们发现我们测量的恒星半高宽有了大约0 . 45的显著改善。恒星的FWHM值变化很大，每次观测的R波段焦点FWHM中值从0 .“97到2 .”15不等。偶尔可获得显著的亚弧秒视程，R的值低至0 .“65 FWHM。可能仍然有一个显着的望远镜贡献的看到在VATT，但附近的树木一样高的圆顶目前的主导因素。
We present measurements of sky surface brightness and seeing on Mount Graham, obtained at the Vatican Advanced Technology Telescope (VATT) during 16 observing runs between 1999 April and 2003 December. We show that the sky surface brightness is significantly darker during photometric conditions and can be highly variable over the course of a single observing run, as well as from one run to the next, regardless of photometricity. In our photometric observations, we find an average low air mass (sec z<1.2) sky surface brightness of 22.00, 22.53, 21.49, and 20.88 mag arcsec−2 in U, B, V, and R, respectively. The darkest run (2000 February in U and 2001 February in BVR) had an average sky surface brightness of 22.38, 22.86, 21.72, and 21.19 mag arcsec−2 in U, B, V, and R, respectively. With these results, we show that under the best conditions, Mount Graham can compete with the darkest sites in Hawaii and Chile, thanks in part to the strict dark‐sky ordinances in place in Tucson and Safford. We expect the sky over Mount Graham to be even darker than our 1999–2003 results during solar minimum (2006–2007). We find a significant improvement of about 0 .″45 in our measured stellar FWHM after improvements to the telescope were made in summer and fall 2001. Stellar FWHM values are highly variable, with median R‐band focus FWHM values in each observing run ranging from 0 .″97 to 2 .″15. Significant subarcsecond seeing was occasionally achieved, with values as low as 0 .″65 FWHM in R. There may still be a significant telescope contribution to the seeing at the VATT, but nearby trees as high as the dome are currently the dominant factor.