标题： 星链低地轨道暗卫星的光学至近红外亮度测量以及暗化处理的效果 显示英文标题

标题： Optical-to-NIR magnitude measurements of the Starlink LEO Darksat satellite and effectiveness of the darkening treatment

摘要： 四次对Starlink的LEO通信卫星Darksat和STARLINK-1113的观测是在两个夜晚使用两台望远镜进行的。 Chakana 0.6米望远镜位于Ckoirama天文台（智利），分别于2020年3月5日（UTC）和2020年3月7日（UTC）使用Sloan r'和Sloan i'滤镜观测了这两颗卫星。 ESO VISTA 4.1米望远镜配备VIRCAM仪器，分别于2020年3月5日（UTC）和2020年3月7日（UTC）在NIR J波段和Ks波段观测了这两颗卫星。 Darksat图像的校准、图像处理和分析显示，当缩放至550公里的距离（天光系数$=1$）并校正太阳入射角和观测者相位角时，r $\approx$ 5.6星等，i $\approx$ 5.0星等，J $\approx$ 4.2星等，Ks $\approx$ 4.0星等。 与之相比，STARLINK-1113图像在考虑了距离、太阳入射角和观测相位角后，r $\approx$ 4.9 mag，i $\approx$ 4.4 mag，J $\approx$ 3.8 mag，Ks $\approx$ 3.6 mag。 本文中呈现的数据和结果表明，Starlink为Darksat使用的特殊暗色涂层使Sloan r'波段亮度降低了50%，Sloan i'波段亮度降低了42%，NIR J波段亮度降低了32%，NIR Ks波段亮度降低了28%。 结果表明，这两颗卫星的反射亮度随着波长的增加而增加，且暗色处理的效果在较长波长下有所降低。 这表明，Starlink和其他LEO卫星运营商正在开发的缓解策略需要考虑其他波长，而不仅仅是光学波长。 这项工作强调了继续获取许多不同LEO卫星的多波长观测的重要性，以表征它们的反射特性，并帮助社区开发影响模拟和缓解工具。 显示英文摘要

摘要： Four observations of Starlink's LEO communication satellites, Darksat and STARLINK-1113, were conducted on two nights with two telescopes. The Chakana 0.6\,m telescope at the Ckoirama observatory (Chile) observed both satellites on 5\,Mar\,2020 (UTC) and 7\,Mar\,2020 (UTC) using a Sloan r' and Sloan i' filter, respectively. The ESO VISTA 4.1\,m telescope with the VIRCAM instrument observed both satellites on 5\,Mar\,2020 (UTC) and 7\,Mar\,2020 (UTC) in the NIR J-band and Ks-band, respectively. The calibration, image processing, and analysis of the Darksat images give r\,$\approx$\,5.6\,mag, i\,$\approx$\,5.0\,mag, J\,$\approx$\,4.2\,mag, and Ks\,$\approx$\,4.0\,mag when scaled to a range of 550\,km (airmass $=1$) and corrected for the solar incidence and observer phase angles. In comparison, the STARLINK-1113 images give r\,$\approx$\,4.9\,mag, i\,$\approx$\,4.4\,mag, J\,$\approx$\,3.8\,mag, and Ks\,$\approx$\,3.6\,mag when corrected for range, solar incidence, and observer phase angles. The data and results presented in this work show that the special darkening coating used by Starlink for Darksat has darkened the Sloan r' magnitude by 50\,\%, Sloan i' magnitude by 42\,\%, NIR J magnitude by 32\,\%, and NIR Ks magnitude by 28\,\%. The results show that both satellites increase in reflective brightness with increasing wavelength and that the effectiveness of the darkening treatment is reduced at longer wavelengths. This shows that the mitigation strategies being developed by Starlink and other LEO satellite operators need to take into account other wavelengths, not just the optical. This work highlights the continued importance of obtaining multi-wavelength observations of many different LEO satellites in order to characterise their reflective properties and to aid the community in developing impact simulations and developing mitigation tools.