GCN Circular 21419
Subject
GRB 170728B: TShAO, SAO RAS and AbAO optical observations
Event
Date
2017-08-07T10:23:04Z (8 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (IKI), A. Kusakin (Fesenkov Astrophysical Institute), A.S.
Moskvitin (SAO RAS), O.I. Spiridonova (SAO RAS), R. Inasaridze (AbAO), I.
Reva (Fesenkov Astrophysical Institute), E. Mazaeva (IKI), A. Pozanenko
(IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 170728B (Cenko et al., GCN 21371)
with Zeiss-1000 of SAO RAS (July 29, August 4,5 ), AS-32 telescope of AbAO
(July 29) and Zeiss-1000 telescope of Tien Shan Astronomical Observatory
(July 30,31 August 1,6). Below we report the photometry of the optical
afterglow (D'Avanzo et al., GCNs 21372, 21373; Heintz et al., GCN 21374;
Guidorzi et al., GCN 21375) and upper limits of our observations.
Preliminary photometry is following:
Date UT start t-T0 Filter Exp. OT Err. UL Telescope
(mid, days) (s) (3 sigma)
2017-07-29 00:41:51 0.07228 R 600 n/d n/d 18.6 Z-1000 SAO
2017-07-29 17:27:49 0.79594 CR 43*60 n/d n/d 20.4 AS-32 AbAO
2017-07-30 16:12:56 1.79815 R 97*120 21.93 0.25 22.1 Z-1000 TSHAO
2017-08-01 15:12:51 3.72304 R 60*120 n/d n/d 21.6 Z-1000 TSHAO
2017-08-04 00:41:51 5.98081 R 41*300 22.6 0.23 22.8 Z-1000 SAO
The photometry is based on nearby USNO-B1.0 stars
1601-0108291 15:52:31.54 +70:09:31.7 R2 17.95
1601-0108289 15:52:28.99 +70:09:26.3 R2 18.08
1601-0108260 15:51:57.87 +70:09:53.8 R2 16.87
1601-0108254 15:51:50.88 +70:08:41.2 R2 15.04
1601-0108262 15:52:03.24 +70:07:32.0 R2 16.01
Coordinates of the afterglow obtained from observation on July 30 are
(J2000)
15 51 55.5179 +70 07 21.123 with uncertainties on both coordinates of 0.2
arces which is compatible with coordinates of TNG (D'Avanzo et al., GCN
21373) and VLA (Fong et al., GCN 21395). The finding chart can be found in
http://grb.rssi.ru/GRB170728B/GRB170728B_TShAO_R_170730.png
The light curve of the afterglow based on observations above and photometry
reported in GCNs (Dintinjana et al., GCN 21394; Watson GCN 21389; D'Avanzo
et al., GCN 21372; Heintz et al., GCN 21374; Guidorzi et al., GCN 21375)
can be found in
http://grb.rssi.ru/GRB170728B/GRB170728B_lc+GCNs_v2.png
Based on our observation on July, 30 (~ 1.8 days after burst onset) one can
suggest that the OT experienced rebrightening at that epoch.