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Astron. Astrophys. 340, 62-66 (1998)

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COMPTEL observation of the flaring quasar PKS0528+134

S. Zhang 1, 2, T.P. Li 1 and M. Wu 1

1 Laboratory of Cosmic Ray and High Energy Astrophysics, Institute of High Energy Physics, Academy of Sciences, P.O.Box 918-3, Beijing, P.R. China (zhangs@astrosv1.ihep.ac.cn)
2 Institute of Theoretical Physics, Academy of Sciences, Beijing, P.R. China

Received 10 July 1998 / Accepted 11 September 1998


With a direct demodulation method, we have reanalyzed the data from the COMPTEL observation of PKS0528+134 during the 1993 March flare in [FORMULA]-rays. Our results show that during the flare [FORMULA]-rays were detected at a level approximately 2.4-3.8 times higher than the observed intensity in two earlier COMPTEL observations VP 0 and VP 1 in the energy range 3 MeV to 30 MeV. The 3-30 MeV time variability of the flux follows well the trend as observed by EGRET at higher energies. No convincing excess can be found around the position of PKS0528+134 in the energy range 0.75 MeV to 3 MeV, which indicates a spectral break around 3 MeV. The detections and non-detections in the four standard COMPTEL energy bands are consistent with the earlier reports given by Collmar et al., while the feature that [FORMULA]-rays of the quasar still kept on flaring at energies down to 3 MeV is clearly found.

Key words: galaxies: active – gamma rays: observations – quasars: individual: PKS0528+134

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© European Southern Observatory (ESO) 1998

Online publication: November 3, 1998