GCN Circular 18199
Subject
GRB 150821A: LCOGT Siding Springs early observations
Date
2015-08-24T15:29:32Z (9 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), A. Gomboc (U. Ljubljana),
C. Mundell (U. Bath) on behalf of a larger collaboration report:
The 1-m LCOGT telescopes in Siding Springs (Australia) began observing
Swift GRB 150821A (Troja et al. GCN 18186) on August 21, 10:22 UT (38
minutes after the burst trigger) with SDSS r and i filters under
initially poor sky conditions.
We detect the optical afterglow (Troja et al. GCN 18186; D'Elia et al.
GCN 18187; Kuin et al. GCN 18192; Kruehler et al. GCN 18195) with the
following magnitudes:
Mid Time Exposure Filter Magnitude
(min) (s)
-----------------------------------------------------
135 1680 r' 19.1 +- 0.4
233 480 r' 19.7 +- 0.3
398 720 r' 20.3 +- 0.2
-----------------------------------------------------
Calibration is done against R2 and I values of USNOB-1 nearby stars.