12-20 July 2017
Asia/Seoul timezone
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BEXCO - Room F(201/202/203/204)

[GA233] Precision atmospheric transmission calibration for IACTs with a set of dedicated optical auxiliary instruments


  • Ievgen VOVK

Primary authors

  • Ievgen VOVK (Max Planck Institute for Physics, Munich, Germany)



High-precision ground-based observations of the very high energy (VHE) sources with Imaging Atmospheric Cherenkov Telescopes (IACTs) require accurate calibration in terms of the atmospheric transmission profiles. For this purpose, various cuts on observable parameters are usually applied in order to select the data corresponding to sufficiently good weather conditions. Furthermore, the MAGIC and CTA collaborations rely on dedicated LIDAR instruments to measure the state of the atmosphere nearly in real time. Despite proven to be successful, this technique requires a very powerful LIDAR laser to be used for observations far from zenith, where the atmosphere thickness is high. At the same time, simulations have shown that under such conditions a measurement of the total aerosol thickness is sufficient and a range-resolved aerosol profile not required. Here we describe a setup with a small optical telescope equipped with a spectrograph, capable of providing accurate transmission measurements at any zenith distance. We also discuss its cross-calibration with the existing MAGIC LIDAR and a dedicated CCD camera with several color filters and demonstrate the performance of the system.