GCN Circular 7475
Subject
GRB 080319C: KAIT OA observations
Date
2008-03-20T05:43:41Z (17 years ago)
From
Weidong Li at UC Berkeley KAIT/LOSS <weidong@astron.berkeley.edu>
W. Li and A. V. Filippenko, University of California, Berkeley,
report on behalf of the KAIT GRB team:
We have analyzed the KAIT observations of the optical afterglow (OA) of GRB
080319C (GCN 7442, GCN 7460) as reported in GCN 7441. Our first 5 s unfiltered
observation started at 12:27:11 UT, 75 s after the BAT trigger. Four subsequent
5 s exposures from t = 81 s to 100 s indicate a smoothly decaying behavior (but
perhaps not power law). After reaching a minimum at t = 180 s (or perhaps a bit
earlier), the OA brightened steeply to a second prominent peak centered at t ~
320 s, after which the OA decayed as an approximate power law, with evidence
for a gradually steepening decay index. Selected photometry, all unfiltered but
calibrated to the R band via USNO B1:
t_start (s) exp (s) mag mag_err
75 5.0 17.353 0.057
100 5.0 17.71 0.062
180 20.0 17.95 0.051
271 20.0 17.322 0.022
362 20.0 17.32 0.023
453 20.0 17.487 0.027
845 20.0 18.06 0.048
1429 20.0 18.866 0.096