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GCN Circular 17106

GRB 141121A: three epochs of SAO RAS optical observations
2014-11-27T18:23:54Z (10 years ago)
Vladimir Sokolov at SAO RAS <>
A.S. Moskvitin and V.N. Komarova report on behalf of a larger team:

We observed the field of GRB 141121A (Lien et al., GCN 17075)
with the SAO RAS 1-m Zeiss-1000 telescope at three nights:
2014.11.24/25, 25/26, 26/27.

The GRB OT (Tanga et al., GCN 17078) is clearly detected
in our stacked frames each night. Our charts can be found at

We used nearby SDSS stars for calibration. The "ugriz" magnitudes
were converted to "UBVRI" with the Lupon-2005 equations. Our OT
brightness measurements are in good agreement with R-band values
estimated within the close epochs and reported in the GCN circulars:
Kuroda et al. (GCN 17098), Mazaeva et al. (GCN 17102). Our OT
magnitudes are also similar to r-band measurements by Watson et al.
(GCN 17100) and Butler et al. (GCN 17101).
Our preliminary results are presented in the following table:
Date   T-T0  UT_start-end Exp.,s  R_mag
24.942 3.782 20:14--00:59  900 20.31+/-0.09
25.956 4.796 22:16--23:38 3600 20.86+/-0.04
26.980 5.820 22:12--00:50 4800 21.36+/-0.09
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