TITLE:   GCN CIRCULAR
NUMBER:  45595
SUBJECT: GRB 260914A: Mondy and TShAO optical observations
DATE:    26/09/16 16:00:26 GMT
FROM:    Alina Volnova at IKI RAS <alinusss@gmail.com>

A. Volnova (IKI), E. Klunko (ISTP), I. Reva (FAI), A. Pozanenko (IKI), A. Moskvitin (SAO RAS), N. Pankov (IKI) report on behalf of IKI-GRB-FuN:
 
We observed the field of the GRB 260914A detected by SVOM/ECLAIR (Wang et al., GCN 45562) and Fermi/GBM (Hamburg, GCN 45569) at z = 0.778 (Saccardi et al., GCN 45579) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy), and the Zeiss-1000 1m telescope of the Tien-Shan Observatory (TSHAO) taking several frames in R-band. The observations at Mondy started on Sep. 14 (UT) 14:51:19 (i.e., ~3.5h after the trigger), followed by the observations at TShAO starting on Sep. 14 (UT) 19:06:53 (i.e., ~8h after the trigger).
 
The optical/NIR counterpart (Akl et al., GCN 45564; Palmerio et al., GCN 45565; Li et al., GCN 45566; Shi et al., GCN 45567; Saccardi et al., GCN 45568; Saccardi et al., GCN 45579; Yang et al., GCN 45582; Brivio et al., GCN 45583) is detected in the stacked frames of both observatories.
The photometry and observational details are the following:
 
Date        UT start  t-T0      Exp,    Filter Obj    Err   UL      Site/Telescope
                     (mid,days) (n*s)                      (3sigma)
2026-09-14  14:51:19  0.17348   18*120  R      21.14  0.08  22.4    Mondy/AZT-33IK
2026-09-14  19:06:53  0.37395   68*90   R      21.29  0.19  22.1    TShAO/Z1000  
 
The preliminary photometry (Vega) is based on nearby PS1 stars (Lupton 2005 transformation) and not corrected for the Galactic extinction.
 
The photometry of the source is affected by the underlying host galaxy reported by Saccardi et al. (GCN 45579) with Legacy survey magnitudes g=22.91, r=22.08, z=21.39.