GCN Circular 13700
Subject
GRB 120817B: Deep limit on the optical afterglow from du Pont and Magellan observations
Date
2012-08-22T18:26:16Z (13 years ago)
From
Wen-fai Fong at CFA <wfong@cfa.harvard.edu>
W. Fong, E. Berger (Harvard), D. Kelson, R. Williams (Carnegie) report:
"We re-observed the BAT-refined location of the IPN short-duration GRB
120817B (GCNs 13670, 13692) with the Inamori-Magellan Areal Camera and
Spectrograph (IMACS) mounted on the Magellan/Baade 6.5-m telescope starting
on 2012 Aug 21.410 UT, 4.2 days post-burst and 3.3 days after our initial
LCO/WFCCD observations (GCN 13672). We obtained 2x300-sec exposures in
R-band in 0.92" seeing. Digital image subtraction with our first
observations using the ISIS software package reveals no evidence for a
fading optical source in or around the BAT error circle. Calculating the
zeropoint using a Stetson standard star field at the same airmass, we place
a 3-sigma limit of R(Vega)>23.3 mag on the optical afterglow of GRB 120817B
at 23.7 hours after the burst."