GCN Circular 44662
Subject
GRB 260509A: CrAO ZTSh optical upper limit
Event
Date
2026-05-18T13:49:55Z (7 days ago)
From
Alexander Moskvitin at SAO RAS <mosk@sao.ru>
Via
Web form
A. Moskvitin (SAO RAS), A. Pozanenko (IKI), V. Rumyantsev (CrAO),
N. Pankov (IKI), A. Volnova (IKI) report on behalf of IKI GRB-FuN.
We observed the field of the GRB 260509A (Götz et al., GCN 44504)
with the Shajn 2.6-meter telescope (ZTSh) of the Crimean Astrophysical
Observatory (CrAO). We obtained 40*120 s exposures R filter
on 2026-05-15 19:45:59--21:09:48 UT (5.94218 days after trigger).
We did not detect the OT (O'Neill et al., GCN 44505; Saccardi et al.,
GCN 44506; Wu et al., GCN 44507; Sánchez Álvarez et al., GCN 44509;
Zheng et al., GCN 44510; Kechin et al., GCN 44512; Belkin, GCN 44513;
Corcoran et al., GCN 44514; Bochenek and Perley, GCN 44516; Moskvitin
and Spiridonova, GCN 44563; Mo et al., GCN 44590; Li et al., GCN 44598)
down to the 3-sigma limiting magnitude of R_lim = 24.2.
This preliminary photometry is based on nearby stars from the USNO-B1
catalogue (R2 magnitudes) and is not corrected for the Galactic
extinction.