TITLE:   GCN CIRCULAR
NUMBER:  29549
SUBJECT: GRB 210222B: Liverpool Telescope optical detection
DATE:    21/02/23 00:32:17 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley@ljmu.ac.uk>

D. A. Perley (LJMU) reports:

A short ugriz imaging sequence of the optical afterglow of GRB 210222A 
(Gropp et al. 29545) was obtained using IO:O on the robotic Liverpool 
Telescope between 23:39 and 23:50 UT on 2021-02-22.  Photometry relative 
to PS1 standards in the field gives the following magnitudes:

t-t0 (d)      magnitude
0.04333 :  g = 18.67 +/- 0.04
0.04440 :  r = 18.21 +/- 0.03
0.04544 :  i = 18.01 +/- 0.03
0.04971 :  z = 17.83 +/- 0.06

The g-band photometry lies below an extrapolation of the other bands and 
the source is not detected in u-band, which may suggest a moderately 
high redshift.











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