Observations of Mkn 421 during 1997 and 1998 in the energy range above 500GeV with the HEGRA stereoscopic Cherenkov telescope system

Authors
Aharonian, FA Akhperjanian, AG Andronache, M Barrio, JA Bernlohr, K Bojahr, H Calle, I Contreras, JL Cortina, J Daum, A Deckers, T Denninghoff, S Fonseca, V Gonzalez, JC Gotting, N Heinzelmann, G Hemberger, M Hermann, G Hess, M Heusler, A Hofmann, W Hohl, H Horns, D Ibarra, A Kankanyan, R Kettler, J Kohler, C Konopelko, A Kornmeyer, H Kestel, M Kranich, D Krawczynski, H Lampeitl, H Lindner, A Lorenz, E Magnussen, N Mang, O Meyer, H Mirzoyan, R Moralejo, A Padilla, L Panter, M Petry, D Plaga, R Plyasheshnikov, A Prahl, J Puhlhofer, G Rauterberg, G Renault, C Rhode, W Rohring, A Sahakian, V Samorski, M Schilling, M Schroder, F Stamm, W Volk, HJ Wiebel-Sooth, B Wiedner, C Willmer, M Wittek, W
Citation
Fa. Aharonian et al., Observations of Mkn 421 during 1997 and 1998 in the energy range above 500GeV with the HEGRA stereoscopic Cherenkov telescope system, ASTRON ASTR, 350(3), 1999, pp. 757-764
Citations number
43
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
00046361 → ACNP
Volume
350
Issue
3
Year of publication
1999
Pages
757 - 764
Database
ISI
SICI code
0004-6361(199910)350:3<757:OOM4D1>2.0.ZU;2-E
Abstract
Since its commissioning in fall 1996, the stereoscopic system of Imaging At mospheric Cherenkov Telescopes (IACTs) of HEGRA, with an energy flux sensit ivity nu F-nu at 1 TeV of 10(-11) erg cm(-2) s(-1) for one hour of observat ion time, has been used to monitor the BL Lac object Mkn 421 on a regular b asis. In this paper, we report detailed temporal and spectral information a bout the TeV characteristics of Mkn 421 in 1997 and 1998. We study the ligh t curve, the shortest time scales of flux variability, the differential spe ctra on a diurnal basis for several days with good gamma-ray statistics, an d the time-averaged energy spectrum. Special emphasis is put on presenting the data taken during the world-wide April 1997 multiwavelength campaign.