GCN Circular 44582
Subject
GRB 260511B: SAO RAS optical observations
Event
Date
2026-05-12T15:32:19Z (5 months ago)
From
Alexander Moskvitin at SAO RAS <mosk@sao.ru>
Via
Web form
A. Moskvitin (SAO RAS) and A. Pozanenko (IKI),
report on behalf of GRB the follow-up team.
We observed the field of the GRB 260511B discovered by Fermi
(The Fermi GBM team, GCN 44542; Roberts, GCN 44554), SVOM
(Godet et al., GCN 44543), NuSTAR (Waratkar and Grefenstette,
GCN 44556), AstroSat CZTI (Arya et al., GCN 44560);
EP-FXT (Fu et al., GCN 44578) with the Zeiss-1000, 1m telescope
of the SAO RAS equipped with the CCD photometer.
Observations were performed in B, V, Rc, Ic filters and started
on May 11, 19:08:40 UT (8.14 hours after the trigger).
The OT (Wu et al., GCN 44547; Sasada et al., GCN 44549;
Jiang et al., GCN 44551; Wu et al., GCN 44552; Vijaykumar et al.,
GCN 44561; de Ugarte Postigo et al., GCN 44565; Lee et al., GCN 44567;
Li et al., GCN 44568; Wang et al., GCN 44571; Belkin et al.,
GCN 44572; Adami et al., GCN 44573; Saccardi et al., GCN 44574;
Rajabov et al., GCN 44576; Pérez-Fournon et al., GCN 44577;
Novotný et al., GCN 44580; also detected in NIR by Li et al.,
GCN 44557) is clearly detected in all frames with the following
brightness.
Date T_start T_end t_mid-T0, exp, s filter mag +/- err
UT hours
2026-05-11T19:14:19--19:54:19 8.56306 3*300 B 19.56 +/- 0.03
2026-05-11T19:20:15--19:40:09 8.49444 2*120 V 19.09 +/- 0.04
2026-05-11T19:08:40--19:43:12 8.42333 3*120 Rc 18.75 +/- 0.02
2026-05-11T19:11:24--19:51:31 8.51542 5*120 Ic 18.50 +/- 0.05
This preliminary photometry is based on nearby SDSS stars
(using Lupton 2005 transformation equations)
and is not corrected for Galactic extinction.