GCN Circular 38901
Subject
GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
Event
Date
2025-01-10T22:51:16Z (9 months ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
Web form
A. Moskvitin, O. Spiridonova (SAO), A. Pozanenko (IKI), N. Kapitanov (INASAN), N. Pankov (IKI, HSE) report on behalf of larger GRB follow-up GRB IKI FuN collaboration.
We observed the field of the GRB 250109A / EP250109a (Li et al.,
GCN 38864; Fermi GBM team, GCN 38873) with two telescopes,
2-m Zeiss-2000 of Terskol observatory and 1-m Zeiss-1000 of SAO RAS on January 9. We obtained 100 x 60 sec. images R band on Jan. 09, 19:36:42--21:28:07 UT with 2-m telescope and 11 x 300 sec. images in Rc band on Jan. 09, 21:12:33--22:23:56 UT with 1-m telescope.
In the stacked image of Zeiss-2000 observation we marginally detect the afterglow candidate (Qiu et al., GCN 38872) within XRT error circle (Kennea et al., GCN 38899). Photometry of the staked images is the following:
Date UT start t-T0, h(mid) Filter Exp.,s OT, err, UL(3sigma) Telescope
25-01-09 19:36:42 14.254 R 100 x 60 22.5 0.4 22.4 Zeiss-2000
25-01-09 21:12:33 15.518 Rc 11 x 300 n/d n/d 22.2 Zeiss-1000
The photometry is based on nearby stars of the PS1 catalog (Lupton 2005 transformations) and not corrected for the Galactic extinction.