High-energy TeV observations of gamma-ray blazars Mkn 421, Mkn 501, Mkn 180 and OJ 287

Abstract

The radio-loud active galactic nuclei having the radio emission arising from a core region rather than from lobes are often referred to as and include BL Lacertae (BL Lac) objects, flat spectrum radio quasars. We present a results of long term observations of know blazars of BL Lac type objects Mkn 421 and Mkn 501, as well as Mkn 180 and OJ 287 which was recently detected by SHALON Cherenkov telescopic system. The integral average gamma-ray fluxes of Mkn 180 and OJ 287 are (0:65 § 0:09) £ 10 i12 cm i2 s i1 and (0:26 § 0:07) £ 10 i12 cm i2 s i1 respectively. The integral average gamma-ray fluxes of Mkn 421 and Mkn 501 were found as (0:63 § 0:05) £ 10 i12 cm i2 s i1 and (0:86 § 0:06) £ 10 i12 cm i2 s i1 respectively. The spectra and images of these blazars are obtained. Also, spectral energy distributions are presented. Extreme variability in different wavelengths including VHE gamma rays is the most distinctive feature of BL Lac. For example, the significant increase of Mkn 501 flux was detected in 1997 with the VHE ground telescopes all over the world. A number of significant increases had been detected from Mkn 421 and Mkn 501 on the year time-scales. These observations are carrying out with SHALON mirror telescopes at the Tien-Shan high mountainous Observatory of P.N. Lebedev Physical Institute.