2011ATel.3161....1M

The unidentified and variable TeV gamma-ray source HESS J0632+057 was recently reported to show a strong flux increase in X-rays by Swift (ATel #3152) starting Jan. 23, 2011 and staying active at least up to Feb. 6, 2011. Shortly afterwards an increase in the TeV flux around Feb. 7/8, 2011 was reported by the VERITAS collaboration (Atel #3153).

The TeV source HESS J0632+057 was suggested to be a binary system and the recent X-ray measurements suggest an orbital period of ∼ 320 days (ATel #3152).

MAGIC monitored HESS J0632+057 during the same time period as Swift and VERITAS. We observed the source between Feb. 7-9, 2011 and our preliminary analysis results in a detection of a significant (above 5 standard deviations) gamma-ray signal above 200 GeV. The estimated flux corresponds to about 3.4% of the Crab Nebula flux in the same energy band. No indication of day-to-day variability is found.

Further observations of HESS J0632+057 with MAGIC are planned for the next nights, to monitor the flux level and duration of the gamma-ray activity.

MAGIC consists of two 17m diameter imaging air Cherenkov telescopes operating in stereoscopic mode located on La Palma, Canary Islands, Spain. Questions regarding the MAGIC observations should be directed to Mose Mariotti ().