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GCN Circular 31357

GRB 220101A: Liverpool telescope imaging of a high-redshift afterglow
2022-01-01T22:14:13Z (2 years ago)
Daniel Perley at Liverpool JMU <>
D. A. Perley (LJMU) reports:

We acquired multicolor imaging of the optical afterglow of GRB 220101A
(Tohuvavohu et al., GCN 31347) using the IO:O camera of the 2m robotic
Liverpool Telescope.  The afterglow was observed twice in the griz
filters on 2022-01-01 UT, with the first epoch taking place between
20:07 and 20:17 and the second between 21:21 and 21:31.

Photometry with reference to SDSS secondary standard stars in
the field gives the following magnitudes:

dt(d)   filter mag   unc
0.6236  g      21.97 0.10
0.6254  r      19.84 0.03
0.6271  i      18.48 0.03
0.6288  z      18.20 0.03
0.6749  g      22.21 0.13
0.6767  r      19.92 0.03
0.6784  i      18.58 0.03
0.6802  z      18.27 0.03

Magnitudes are given in the SDSS system and uncorrected for extinction. 
Times are referenced to the BAT trigger time.

The colors are consistent with a moderately high-redshift (z = 4-5) 
afterglow, in agreement with the result of Fu et al. (GCN 31353).

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