GCN Circular 21029
Subject
Swift Trigger 748858: AbAO and TSHAO optical observations
Date
2017-04-21T20:16:17Z (7 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), R. Inasaridze (AbAO), I. Reva
(Fesenkov Astrophysical Institute), A. Kusakin (Fesenkov Astrophysical
Institute), A. Volnova (IKI), V. Ayvazian (AbAO), O. Kvaratskhelia
(AbAO), G. Inasaridze (AbAO), I. Molotov (KIAM), report on behalf of
larger GRB follow-up collaboration:
We observed the field of the SWIFT trigger 748858 (Siegel, et al., GCN
21011) with AS-32 (0.7m) telescope of Abastumani Observatory and with
Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory. In each
observation we fully cover both BAT error circles, initial (Siegel et
al., GCN 21011) and ground-calculated error circle (Sakamoto et al.,
GCN 21017). Within ground-calculated error circle we do not find any
new source in comparison with SDSS catalog. Within XRT error circle of
the source reported in GCN 21017 (Sakamoto et al.) we find the source
which is already mentioned by (Butler et al., GCN 21026). The source
coincides with the star of J131924.35+153001.6 and has the brightness
of R =19.53 +/- 0.04 according to SDSS DR9 and Lupton gri -> R
transformations.
Limiting magnitudes as well as the brightness of the star
J131924.35+153001.6 for each observation are presented below.
Date UT start t-T0 Filter Exp. XRT Err UpLim (3 sigma)
(mid, days) (s)
2017-04-19 17:03:29 0.39918 CR 33*60 19.35 0.06 22.2
2017-04-19 17:37:14 0.42414 R 21*180 19.47 0.05 22.0
Photometry is based on nearby SDSS DR9 stars (Lupton transformations)
J131940.43+152853.2 15.63
J131934.46+152944.3 15.44
J131930.90+152831.0 16.02
J131927.38+153041.9 16.17
J131911.74+152820.9 15.72
J131859.43+153017.2 16.72
J131859.61+152435.2 16.63