GCN Circular 22935
Subject
GRB 180709A: Optical limits
Date
2018-07-09T16:36:22Z (6 years ago)
From
Jules Halpern at Columbia U. <jph1@columbia.edu>
J. P. Halpern (Columbia U.) reports:
I observed the field of Swift GRB 180709A (Marshall et al., GCN 22930)
with an SDSS r filter using the 1.3m McGraw Hill telescope of the
MDM Observatory, beginning 17.6 minutes after the trigger.
Four 5-minute exposures were obtained in morning twilight.
Upper limits at the enhanced Swift-XRT position of Beardmore et al.
(GCN 22933) are listed below, as calibrated to Pan-STARRS1 photometry.
---------------------------------------------
Date(UT) Start(UT) Mid-time T-T0 r(mag)
---------------------------------------------
July 9 11:09:34 1194 s > 22.0
July 9 11:14:41 1501 s > 21.8
July 9 11:19:47 1807 s > 21.4
July 9 11:24:54 2114 s > 21.1
---------------------------------------------
These magnitudes are not corrected for Galactic extinction, which is
considerable at this Galactic latitude of -0.1 deg. According to the
NED implementation of Schlafly & Finkbeiner (2011), A_r = 6.1 mag.