2015/08/27 by Jan Ebr, Ebr, Jan, Petr Janeček +5
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #FOS: Physical sciences #Gamma-ray bursts and supernovae #Instrumentation and Methods for Astrophysics (astro-ph.IM) #Radiation Detection and Scintillator Technologies
paper · pdf · doi:10.48550/arxiv.1508.06798
openalex publication_date 2015/08/27 · openalex created_date 2022/10/01 · openalex updated_date 2026/07/28
The Cherenkov Telescope Array (CTA) is the next generation of ground-based\nvery high energy gamma-ray instruments and is planned to be built on two sites\n(one in each hemisphere) in the coming years, with full array operation\nforeseen to begin 2020. The goal of performing high precision gamma-ray energy\nmeasurements while maximizing the use of observation time demands detailed and\nfast information about atmospheric conditions. Besides LIDARs designed to\nmonitor clouds and aerosol content of the atmosphere in the pointing direction\nof the CTA telescopes, we propose to use the "FRAM" (F(/Ph)otometric Robotic\nAtmospheric Monitor) device, which is a small robotic astronomical telescope\nwith a large field of view and a sensitive CCD camera that together ensure\nprecise atmospheric characterization over the complete field-of-view of the\nCTA. FRAM will use stellar photometry to measure atmospheric extinction across\nthe field of view of the CTA without interfering with the observation (unlike\nlaser-based methods). This allows FRAM to operate with high temporal resolution\nand provide both real-time data for on-the-fly scheduling decisions and an\noffline database for calibration and selection of scientific data. The fast\nrobotic mount of the telescope supports quick observation of multiple fields\nwhen the array is split and even a check of the conditions in the directions of\nthe upcoming observations is possible. The FRAM concept is built upon\nexperience gained with a similar device operated at the Pierre Auger\nObservatory. A working prototype of FRAM proposed for CTA is being built in\nPrague for extensive testing before deployment on site; first results and\nexperiences with this prototype are presented.\n