[vsnet-grb-info 19488] GRB 170519A: TShAO and AbAO optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21208
SUBJECT: GRB 170519A: TShAO and AbAO optical observations
DATE:    17/06/05 19:41:04 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), A. Kusakin (Fesenkov Astrophysical 
Institute),  R. Inasaridze (AbAO), I. Reva (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 GRB 170519A (Ukwatta et al., GCN 21106) with 
Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory
starting on May 20 (UT) 18:42:38. We took several images in R-filter
with exposures of 120 s during this night and 2 subsequent nights.
The optical afterglow (Ukwatta et al., GCN 21106; Izzo, et al.,
GCN 21108) is visible in stacked images.

We also observed this field with AS-32 (0.7m) telescope of Abastumani
Observatory on May 21 (UT) 17:22:33. We took several unfiltered frames
with 60 s exposure. In the enhanced XRT error circle (Beardmore et al.,
GCN 21107) we do not detect the afterglow.

Preliminary photometry of the afterglow is following:

Date       UT start   t-T0    Filter Exp.   OT   Err. UL    Telescope
                      (mid, days)     (s)              (3 sigma)

2017-05-20 18:42:38  1.58414  R    24*120  20.06 0.06 21.4 Zeiss-1000
2017-05-21 15:58:25  2.48340  R    39*120  20.95 0.14 21.6 Zeiss-1000
2017-05-22 15:27:05  3.46168  R    39*120  22.20 0.40 21.9 Zeiss-1000
2017-05-21 17:22:33  2.52050  CR   20*60   n/d   n/d  20.8 AS-32

The photometry is based on nearby SDSS stars, reported by
Mazaeva et al. (GCN 21169).

The  light curve of the GRB 170519A afterglow based on our observations 
  (GCNs 21162, 21169, 21206)  can be found at
http://grb.rssi.ru/GRB170519A/GRB170519A_lc.png