SGER: Prototype Test Bench for Stellar Intensity Interferometry with Atmospheric Cherenkov Gamma Ray Telescopes

在大多数情况下，天文学家更喜欢在月亮黑暗的时候使用望远镜，对于一些项目，月球增加了太多的背景光，以至于每个月满月周围的8到10个晚上都不使用望远镜。例如，有一组望远镜用来测量宇宙射线进入地球大气层时产生的电磁辐射(切伦科夫辐射)的强度和方向。由于这些信号非常微弱，产生的光线非常微弱，望远镜通常会有近三分之一的夜晚处于闲置状态。然而，研究更亮物体的研究项目，如附近的恒星，仍然可以在月亮发光的时候进行。犹他大学的斯蒂芬·勒博赫克博士正计划在“明亮时期”利用这种可用的望远镜作为强度干涉仪来测量恒星的直径。这种测量在使用强度干涉法之前就已经完成，但这项技术已经失宠，被所谓的相位干涉仪所取代。位相干涉测量对于温度较低的红星很有效，因为红光和红外光的波长较长。然而，对于像我们的黄色太阳这样的恒星，以及更热、更蓝的恒星，强度干涉测量的效果要好得多。NSF的天文科学高级技术和仪器计划部门正在为LeBohec博士提供资金，以获得和开发在切伦科夫望远镜上进行强度干涉测量所需的仪器。

For the most part, astronomers prefer to use their telescopes during the dark of the moon and for some projects the moon adds so much background light that telescopes go unused every month for the eight to ten nights surrounding full moon. For example, there are arrays of telescopes used to measure the intensity and the direction of electromagnetic radiation (Cherenkov radiation) caused when cosmic rays enter the earth's atmosphere. Because these signals are very weak and the resulting light very faint, the telescopes typically sit idle nearly a third of the nights. However, research projects that investigate brighter objects like nearby stars can still be conducted while the moon is shining. In order to make use of such available telescopes during "bright time," Dr. Stephan LeBohec of the University of Utah is planning to use them during bright time as an intensity interferometer to measure the diameters of stars. This kind of measurement has been done before using intensity interferometry, but the technique has fallen out of favor and been superseded by so-called phase interferometers. Phase interferometry works well for cooler, red stars where the red and infrared light has longer wavelengths. However, for stars like our yellow sun as well as for hotter and bluer stars intensity interferometry performs much better. NSF's Division of Astronomical Sciences Advanced Technologies and Instrumentation Program is providing funding for Dr. LeBohec to acquire and develop the instrumentation necessary for the intensity interferometry measurements to be made on the Cherenkov telescopes.