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GCN Circular 21276

GRB 170626A: TShAO optical observations
2017-06-27T16:50:15Z (6 years ago)
Alexei Pozanenko at IKI <>
A. Volnova (IKI),  A. Pozanenko (IKI), I. Reva (Fesenkov Astrophysical Institute),  E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), report on behalf of larger GRB follow-up collaboration:

We observed the field of the Swift GRB 170626A (Marshall et al., GCN Circ. 21264; Hamburg & Meegan, GCN Circ. 21266) 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 total exposure of 1130 s.  The optical afterglow (Moskvitin et al., GCN 21268; de Ugarte Postigo, et al., GCN 21269) is clearly visible in a stacked image.

Preliminary photometry of the afterglow is following:

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

2016-06-26 16:47:33  0.30832  R    1130   19.87  0.13 21.0  

The magnitude is also compatible with a magnitude of the afterglow reported by Lipunov (GCN 21272) after observation at the same epoch.
Taken into account that between our observation at ~7.4 hours (mid time) and TNG observation at 11.53 hours (Melandri et al., GCN 21270) the magnitude of the aftegrlow did not change one may suggest either flare like activity or plateau phase of the afterglow and the burst can interesting for follow up observations.

The  finding chart can be found at

The photometry is based on nearby SDSS stars, part of them already used in Moskvitin et al. (GCN 21169).

SDSS_id              R_Lupton Err
J110107.23 +564104.2 15.987 0.013
J110157.37 +563628.5 15.225 0.013
J110211.15 +563624.1 15.177 0.012
J110206.51 +563744.1 14.808 0.012
J110111.46 +563755.3 15.480 0.012
(GCN 21169)
J110106.88 +563153.7 16.389 0.013
J110125.73 +563134.0 18.332 0.023
J110124.28 +563251.1 17.839 0.017
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