On teraelectronvolt γ-ray emission from Markarian 501 in 2004

摘要

Galaxy Markarian 501 was observed with the Cerenkov telescope GT-48 at the SRI Crimean Astrophysical Observatory. A total of about 18 hr of source exposure in good weather conditions for 20 nights in the period between May and July 2004 were used for processing the Cerenkov light images induced by extensive air showers. Discrimination analysis has shown the excess number of detected very-high-energy photons in the direction of the observed object at the 5.6s level. The emission from the object was characterized by the variability of its intensity on a monthly scale. The analysis of X-ray data has also shown enhanced activity from the object in the observation period.