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GCN Circular 2384

Magellan Observations of GRB030725 (=H2779)
2003-09-16T13:46:36Z (21 years ago)
Roland Vanderspek at MIT <>
Magellan Observations of GRB030725 (=H2779)

A. Dullighan, N. Butler, R. Vanderspek, J. Villasenor, and G. Ricker


We have observed the optical counterpart (Monard, GCN 2324) of the
HETE-discovered Gamma Ray Burst GRB030725(=H2779; Shirasaki et al, GCN
2322) with the MagIC instrument on the 6.5m Magellan Clay telescope at
Las Campanas Observatory in Chile. Two 300 second, Sloan r-band
exposures were taken in an interval centered on August 1.305 UT, at 6.81
days after the burst.  Another two 360 sec Sloan r-band exposures were
taken on August 2.166 UT, at 7.68 days after the burst.

   Date UT	  r Magnitude
August 1.305	 22.25 +/- 0.05
August 2.166	 22.55 +/- 0.05

These measurements are consistent with the late time decay slope of -1.4
+/- 0.1 as reported by Jorgensen, et al. (GCN 2344).

A lightcurve for the optical afterglow of GRB 030725 can be seen at:

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