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Two Variable Radio Sources Near the Position of GRB 940301We report on the results of a search for a radio counterpart to the strong gamma-ray burst GRB 940301. Observations with the Westerbork Synthesis Radio Telescope of the Compton Telescope error box region of GRB 940301 began on March 4, 1994, at 21 cm and April 2, 1994, at 92 cm. No flux density variations were detected at 92 cm above S= 10 mJy (5 (sigma)) within a period of 1 to 4 months after the burst. However, when we compared the field with Westerbork Northern Sky Survey data, taken two years prior to GRB 940301, we found two radio sources with significantly increased flux densities. These sources, only 17 min. apart, are located at the 2.3 and 2.6(sigma) Compton Telescope confidence contours. Their separation from the Inter Planetary Network annulus virtually excludes association with GRB 940301. Further observations in January 1996 reveal that the sources continued to change in flux density. The relatively large flux density variations at 92 cm, compared to those at higher frequencies, and the inverted spectra in the frequency range from 325-38O MHz make the sources somewhat unusual. Because the sources were already detected at 5 GHz in 1986 most, if not all, of the radio emission is probably associated with activity in Active Galactic Nuclei in distant galaxies.
Document ID
19980227499
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Galama, T. J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
DeBruyn, A. G.
(NASA Marshall Space Flight Center Huntsville, AL United States)
vanParadijs, J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Hanlon, L.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Groot, P. J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
VanDerKlis, M.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Strom, R.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Spoelstra, T.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Bennett, K.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Fishman, G. J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Hurley, K.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
August 18, 2013
Publication Date
January 1, 1997
Publication Information
Publication: Astronomy and Astrophysics
Publisher: Springer-Verlag
Volume: 321
Subject Category
Space Radiation
Distribution Limits
Public
Copyright
Other

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