TITLE:   GCN CIRCULAR
NUMBER:  31323
SUBJECT: GRB 211227A: Liverpool Telescope upper limits
DATE:    21/12/28 05:27:43 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley@ljmu.ac.uk>

D. A. Perley (LJMU) reports:

We acquired imaging at the position of GRB 211227A (Beardmore et al., 
GCN 31316) using the IO:O camera of the 2m robotic Liverpool Telescope. 
The field was observed twice in the griz filters on 2021-12-28 UT, with 
the first epoch taking place between 00:36:10 and 00:45:43 and the 
second between 02:04:43 and 02:14:18.

No new source is detected within or near the XRT position (Goad et al., 
GCN 31322) after digital subtration of reference imaging from the 
Pan-STARRS 1 survey.  Photometry with reference to PS1 secondary 
standard stars in the field gives the following upper limits:

dt(days)    magnitude
0.04449     g > 21.99
0.04625     r > 22.62
0.04799     i > 22.68
0.04974     z > 21.36

The LCO source mentioned by Strausbaugh et al. (GCN 31321) is detected 
in PS1 reference imaging and is also marginally detected in both sets of 
(unsubtracted) LT images and is far from the enhanced XRT error circle, 
suggesting it is unlikely to be related to the GRB.





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