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GCN Circular 20508

GRB 170121B: LCO FTN observations
2017-01-23T08:41:54Z (7 years ago)
Cristiano Guidorzi at Ferrara U,Italy <>
C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc 
(U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large 
collaboration report:

We observed Fermi GRB 170121B (Hamburg et al. GCN 20505) on January 23, 
07:21 UT (1.7 days since the GRB) with the 2-m LCO Faulkes Telescope 
North in Hawaii with SDSS r and i filters. We do not detect the MASTER 
optical counterpart (Lipunov et al. GCN 20502) down to the following limits:

Mid Time      Exposure       Filter       Magnitude (AB)
(days)           (s)
1.69            2x120        SDSS-R        > 21.0
1.69            2x120        SDSS-I        > 19.5

as calibrated against nearby USNO-URAT1 sources.
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