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FACT - Searching for periodicity in five-year light-curves of Active Galactic Nuclei
(2018)PoS: Proceedings of ScienceThe First G-APD Cherenkov Telescope (FACT) has been monitoring Active Galactic Nuclei (AGN) for the past five years. The use of robust silicon photomultipliers (SiPMs) allows for a continuous, unbiased sampling even during bright-light conditions. This dataset promises insights into the core regions of AGN by investigating the periodicity of the sources. Periodic changes in the flux could indicate a binary nature of the supermassive black ...Conference Paper -
Using Charged Cosmic Ray Particles to Monitor the Data Quality of FACT
(2018)PoS: Proceedings of Science ~ ICRC2017 proceedingsImaging Air Cherenkov Telescopes (IACT) measure the faint flashes of Cherenkov light emitted by air-showers that are produced when charged particles or gamma rays hit the atmosphere. Therefore, the atmosphere above the IACT is an integral part of the detector. Variations in the performance of the IACT itself, but also changes in the absorption and scattering of Cherenkov light due to clouds or dust affect the interpretation of measured ...Conference Paper -
FACT - Highlights from more than Five Years of Unbiased Monitoring at TeV Energies
(2018)PoS: Proceedings of ScienceThe First G-APD Cherenkov Telescope (FACT) is monitoring blazars at TeV energies. Thanks to the observing strategy, the automatic operation and the usage of solid state photosensors (SiPM, aka G-APDs), the duty cycle of the instrument has been maximized and the observational gaps minimized. This provides a unprecedented, unbiased data sample of almost 9000~hours of data of which 2375 hours were taken in 2016. An automatic quick look ...Conference Paper -
Measuring the Optical Point Spread Function of FACT Using the Cherenkov Camera
(2018)PoS: Proceedings of ScienceFACT, the First G-APD Cherenkov Telescope, is an Imaging Air Cherenkov Telescope (IACT) operating since 2011 at the Observatorio del Roque de los Muchachos on the Canary Island of La Palma. As typical for IACTs, its reflector is comprised of smaller mirror facets and not protected by a dome. In the case of FACT, 30 hexagonal facets form a total mirror area of 9.5 m 2 . Hence, it is crucial to monitor the optical properties of this ...Conference Paper -
Single Photon Extraction for FACT’s SiPMs allows for Novel IACT Event Representation
(2018)PoS: Proceedings of Science ~ Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017)Imaging Atmospheric Cherenkov Telescopes provide large gamma-ray collection areas > 10^4 m^2 and successfully probe the high energetic gamma-ray sky by observing extensive air showers during the night. The First G-APD Cherenkov Telescope (FACT) explores silicon based photoelectric converters (called G-APDs or SiPMs) which provide more observation time with strong moonlight, a more stable photon gain over years of observations, and ...Conference Paper -
FACT – Performance of the First Cherenkov Telescope Observing with SiPMs
(2018)PoS: Proceedings of Science ~ Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017)The First G-APD Cherenkov Telescope (FACT) is pioneering the usage of silicon photo mul- tipliers (SiPMs also known as G-APDs) for the imaging atmospheric Cherenkov technique. It is located at the Observatorio Roque de los Muchachos on the Canary island of La Palma. Since first light in October 2011, it is monitoring bright TeV blazars in the northern sky. By now, FACT is the only imaging atmospheric Cherenkov telescope operating with S ...Conference Paper -
Higher Order Temperature Dependence of SiPM used in FACT
(2018)PoS: Proceedings of Science ~ Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017)Solid state photosensors, usually called SiPM or G-APD, seem ideal devices to be used in Imaging Atmospheric Cherenkov Telescopes (IACT). Nevertheless, their temperature dependence poses questions about their suitability in the harsh environment intrinsic to the operation of IACTs. While detailed measurements in the laboratory are possible with some sample sensors, limited data about the performance and uniformity of large samples exist. ...Conference Paper