EDP Sciences
Free access
Volume 396, Number 3, December IV 2002
Page(s) 923 - 928
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20021434

A&A 396, 923-928 (2002)
DOI: 10.1051/0004-6361:20021434

An unidentified variable gamma-ray source near the galactic plane detected by COMPTEL

S. Zhang1, 2, W. Collmar1 and V. Schönfelder1

1  Max-Planck-Institut für extraterrestrische Physik, PO Box 1603, 85740 Garching, Germany
2  High Energy Astrophysics Lab, Institute of High Energy Physics, PO Box 918-3, Beijing 100039, PR China

(Received 13 May 2002 / Accepted 1 October 2002 )

We report the detection of an unidentified $\gamma$-ray source near the Galactic plane by the COMPTEL experiment aboard the Compton Gamma-Ray Observatory. The source is detected at a significance level of ~7.2 $\sigma$ in the energy range 1-3 MeV and at ~4.6 $\sigma$ in the lower 0.75-1 MeV band in the time period March to July 1995. At energies above 3 MeV are only marginal hints or upper limits obtained. The MeV spectrum has a soft shape. Strong flux variability is found within one year at energies below 3 MeV. Possible counterparts of galactic and extragalactic nature are discussed.

Key words: $\gamma$ rays: observations

Offprint request: S. Zhang, szhang@mail.ihep.ac.cn

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