RA = 10 44 49.957, Dec = +21 31 17.46 (J2000)

GCN Circular #2021: GRB 030329: Optical Decay

J. P. Halpern, N. Mirabal, M. Bureau (Columbia U.), K. Fathi (U. Nottingham) report for the MDM Observatory GRB follow-up team: We monitored the optical afterglow of GRB 030329 (=H2652, Vanderspek et al. GCN 1997), identified by Peterson & Price (GCN 1985) and Torii (GCN 1986), in the R-band with the MDM 1.3m for 7.5 hours beginning on March 30 03:05 UT, 15.5 hours after the burst. During this period, the magnitude declined from R = 15.38 to R = 16.22, referenced to star "A" of Martini et al. (GCN 2012). A fit to the 7.5 hour run yields a power-law decay slope of -1.934 +/- 0.005, in agreement with contemporaneous measurements of Garnavich et al. (GCN 2018) and Smith (GCN 2019), although it is apparent that the slope is continuing to steepen further. A graph of the preliminary differential magnitude light curve is available at http://www.astro.columbia.edu/~jules/030329_lc.ps We thank J. Kemp for providing the data reduction pipeline. This message may be cited.