[vsnet-grb-info 19845] GRB 170921A: LCO 2m telescope observations
GCN Circulars
gcncirc at capella2.gsfc.nasa.gov
Fri Sep 22 21:08:06 JST 2017
TITLE: GCN CIRCULAR
NUMBER: 21910
SUBJECT: GRB 170921A: LCO 2m telescope observations
DATE: 17/09/22 12:07:33 GMT
FROM: Cristiano Guidorzi at Ferrara U,Italy <guidorzi at fe.infn.it>
C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath),
A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara, D. Morris,
and B. Gendre (U. Virgin Islands) on behalf of a large collaboration report:
We began observing Swift GRB 170921A (D'Ai et al. GCN 21901) on
September 21, from 14:52 to 15:05 UT (from 24 to 37 minutes since the
GRB trigger time) with the LCO 2-m telescope in Hawaii in the SDSS R and
I filters. Within the enhanced Swift-XRT circle (Beardmore et al. GCN
21906) we do not detect any optical counterpart down to the following
limits, in agreement with previous reports (Klotz et al. GCN 21903;
Kuroda et al. GCN 21905; Feng et al. GCN 21907; Malesani et al. GCN 21909):
Mid Time Exposure Filter Magnitude (AB)
(min) (s)
-------------------------------------------------------
26.8 5x60 SDSS-R > 20.7
34.0 3x60 SDSS-I > 19.8
-------------------------------------------------------
as calibrated against nearby SDSS objects.
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