GCN Circular 37313
Subject
GRB 240825A: SAO RAS optical observations
Event
Date
2024-08-28T00:51:15Z (a year ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS)
report on behalf of the GRB follow-up team.
We observed the field of the GRB 240825A (The Fermi GBM team,
GCN 37273; Gupta et al., GCN 37274; Lalla et al., GCN 37288;
Evans et al., 37290; Gropp et al., GCN 37294; Joshi et al.,
GCN 37298; Sharma et al., GCN 37301; Frederiks et al., GCN 37302)
with the SAO RAS 1-meter telescope Zeiss-1000 equipped with the
CCD-photometer on August 25/26, 26/27 and 27/28.
The weather conditions and seeing during the first and the second
nights were poor. The third night was good.
We obtained series of exposures in Rc band on
2024-08-25T20:37:53 -- 2024-08-25T22:32:59;
2024-08-26T22:33:48 -- 2024-08-27T01:29:03;
2024-08-27T19:51:04 -- 2024-08-27T21:15:46.
The OT (Gupta et al., GCN 37274; Jiang et al., GCN 37275;
Dutton et al., GCN 37276; Odeh and Guessoum, GCNs 37277, 37299;
Zhang et al., GCN 37278; Li et al., GCN 37280; Izzo and Malesani,
GCN 37287; Lipunov et al., GCN 37289; Leonini et al., GCN 37291;
Wu et al., GCN 37292; Martin-Carrillo et al., GCN 37293;
Brivio et al., GCN 37295; Kuin et al., GCN 37296; Le Floc’h et al.,
GCN 37300; Zheng and Filippenko, GCN 37304; Wang et al., GCN 37306;
Maksut et al., GCN 37307; Melandri et al., GCN 37310) is clearly
detected in the stacked frame only during the third night.
The non-detection of OT during our first and second nights is
consistent with the magnitudes reported by the other teams.
Our results are following.
Date T_mid - T0, d exp, s magnitude
Aug 25 0.2378 1080 R_lim = 19.5
Aug 26/27 1.3392 1483 R_lim = 21.0
Aug 27 2.1948 4200 R = 21.88 +/- 0.07
Our stacked frames are calibrated against nearby Pan-STARRS objects
and not corrected for the MW extinction.