Münster 2017 – scientific programme
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T: Fachverband Teilchenphysik
T 59: Gammaastronomie 3
T 59.1: Group Report
Tuesday, March 28, 2017, 16:45–17:05, H 2
FACT - Results from Five Years of TeV Monitoring — Daniela Dorner1 and •Jens Buss2 for the FACT collaboration — 1Universität Würzburg, Germany — 2TU Dortmund, Germany
The First G-APD Cherenkov Telescope (FACT) is monitoring blazars to study their variability and its origin. Pioneering the usage of SiPMs, the data taking efficiency was maximized reaching more than 2350 h of physics data in 12 months. Deriving a spectrum of the TeV standard candle Crab Nebula, the excellent performance of FACT was illustrated. To foster simultaneous multi-wavelength (MWL) observations, crucial to understand blazar physics, the FACT quick look analysis provides results with low latency. Based on this, 40 alerts and six astronomer's telegrams (Atels) were sent since March 2014. An early alert in 2012, resulted in detailed observations by the neighboring MAGIC telescopes on Mrk 501 providing useful information for the associated MWL study. In 2014, the follow-up by H.E.S.S. to another alert on the same source provides a high resolution spectrum complementing FACT's dense long-term light curve. A moderate flux flare of Mrk 421 in Dec 2015 triggered the ongoing target-of-opportunity program with X-ray satellites resulting in time-resolved spectral energy distributions. In 2016, 1ES 1959+650 underwent the brightest flaring activity in TeV energies since 2002. From FACT, an unprecedented dense light curve is available resulting in 26 alerts, five Atels and valuable MWL data. Studies about the long-term behaviour of several sources based on the FACT light curves are ongoing. The presentation summarizes experience and results from more than five years with FACT.