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GCN Circular 8997

GRB 090313: Gemini-S photometry
2009-03-14T10:38:18Z (15 years ago)
Daniel Perley at U.C. Berkeley <>
D. A. Perley (UC Berkeley) reports on behalf of a larger collaboration:

Following our spectroscopic integration on the optical afterglow of GRB
090313 (GCN 8994), we acquired one 60s frame in each of g, r, i, and z
filters using Gemini-S (GMOS) in imaging mode between 05:11 and 05:18 UT
(20.07 hours after the burst).  We report the following magnitudes:

g = 21.62 +/- 0.08
r = 20.12 +/- 0.03
i = 19.50 +/- 0.05
z = 19.03 +/- 0.05

The optical SED is well-fit assuming a moderate (A_V ~< 0.4) amount of
SMC-like dust extinction.  The presence of a 2175 A dust feature is
strongly ruled out by the z-band measurement.
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