GCN Circular 2336
Second Epoch Magellan Observations of XRF030723 (=H2777) A. Dullighan, N. Butler, R. Vanderspek, J. Villasenor, and G. Ricker (MIT) write: We have observed the SXC error circle for the HETE-discovered X-ray flash XRF030723 (=H2777; Prigozhin et al, GCN 2313) with the MagIC instrument on the 6.5m Magellan Clay telescope at Las Campanas Observatory in Chile. Two 200 second, Harris R-band exposures were taken in an interval centered on July 28.385 UT, at 5.13 days after the burst. The seeing was ~0.8 arcsec. Coaddition of the images gives a limiting magnitude of R = 24.3. We detect the optical counterpart (Fox et al., GCN 2323) of GRB 030723 at R = 24.2 +/- 0.3. Combining our photometry with that available from the GCN Circulars (Bond, GCN 2329; Dullighan et al., GCN 2326; Fox et al., GCN 2323), we estimate a late time power law decay index of ~2, and an early power law decay of 0.9. The break in the light curve is between 30-50 hours after the burst. Our measurements have been calibrated against the USNO photometry data reported by Henden in GCN 2317. A plot of this light curve can be seen at: http://space.mit.edu/HETE/Bursts/GRB030723/ We gratefully acknowledge observational assistance by Matthew J. Holman and Jeff McClintock. This message may be cited.