GCN Circular 1885
P. Garnavich (Notre Dame), K. von Braun (DTM), K. Stanek (CfA) We have calibrated the R-band images of the GRB 030226 field (Fox et al. GCN 1879; von Braun et al. GCN 1881) taken with the 1-m Swope telescope on Feb. 26 (UT). The Landolt standard field PG1323-086 (Landolt 1992, AJ, 104, 340) was observed at the end of the photometric night. We estimate the following magnitudes for stars near the optical afterglow: Star A 11:33:03.214 +25:51:30.73 (2000) R=15.39 +/-0.05 Star B 11:32:59.808 +25:52:38.73 (2000) R=17.06 +/-0.05 where most of the error is due to the uncertain airmass correction. Star A was noted in GCN 1881 as having a USNO magnitude of 15.0. Using this calibration we find the following brightness for the afterglow from the Swope data: Feb. 26.305 (3.5 hours after the burst) R=18.44 +/-0.05 The images show only a 0.02 mag variation in the brightness of the afterglow over a 20 minutes span. A finder chart for the afterglow and calibrated stars can be found at: http://www.nd.edu/~pgarnavi/grb030226.jpg This message may be cited.