Return to Home Page
TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2017 SUBJECT: GRB 030329: Optical decay and synthesis DATE: 03/03/30 07:57:04 GMT FROM: Paul Price at RSAA, ANU <pap@mso.anu.edu.au> P.A. Price, B.P. Peterson and B.P. Schmidt (RSAA, ANU) report: Synthesis of observations from Rykoff et al. (GCN #1995), Gal-Yam et al. (GCN #1999), Martini et al. (GCN #2012) and from the SSO 40-inch (GCN #1987) yeilds the following decay: R/mag ~ 15.8 + 2.4 log (t/days) with corresponding power-law index alpha = 0.97 +/- 0.03. Hence, though the afterglow is bright, the decay is not unusually shallow (eg, 010222 had alpha1 ~ 0.80). The spectral index, calculated from the B-I colour from Burenin et al. (GCN #2001) and Rumyantsev et al. (GCN #2005) is beta ~ 1.2. Using the measured redshift (Martini et al., GCN #2013; Della Ceca et al., GCN #2015), optical decay and spectral index, we calculate the R-band absolute magnitude of the optical afterglow for t=1 day in the source frame, M_R,1 = -26.7 mag. This is therefore the most intrinsically bright optical afterglow observed to date (with 000301C and 000418 tied for second at M_R,1 = -26.1 mag). The low redshift and the large intrinsic brightness combined to produce an optical afterglow with a large apparent brightness. The redshift of z=0.57 and measured fluence (Vanderspek et al., GCN #1997) implies an isotropic-equivalent energy release of 1.1 x 10^53 erg (30-400 keV). The Frail et al. "standard energy" result implies a jet-break time of around 4 days. At this time, the afterglow should be R ~ 17.3 mag. We encourage polarimetric observations to be made on this timescale to constrain the jet dynamics. This message may be cited.
Return to the Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
