TITLE: GCN CIRCULAR NUMBER: 38291 SUBJECT: GRB 241120A: Mondy and AbAO optical observations DATE: 24/11/21 16:55:29 GMT FROM: XXXX at IKI <alex@cgrsmx.iki.rssi.ru> N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO), V. Aivazyan (AbAO) report on behalf of IKI-GRB-FuN: We observed the field of GRB 241120A detected (The Fermi GBM team, GCN 38279; Gotz et al., GCN 38280) with AZT-33IK telescope of Sayan (Mondy) observatory, and AS-32 telescope of Abastumani observatory (AbAO). The observations started at Mondy on 2024-11-20 at 20:01 UT, i.e. ~0.6 days since trigger. Within the localization circle of INTEGRAL (Gotz et al., GCN 38280) we do not find any evident candidates in comparison with known catalogues. However, there is a source in our observations at the coordinates of (J2000) RA=12:57:04.3 Dec=+52:08:45.8 with uncertainty of 0.2 arcses in both coordinates for which it can be assumed that the source is showing marginal decreasing of brightness. The source is presented at least in PS1, SDSS and DESI. Preliminary photometry of the source is as follows: Date UT_start Exp_time t-T0 Filter OT Err UL (s) (mid, days) (3sigma) 2024-11-20 20:01:27 28*120 0.60798 R 19.85 0.10 22.6 AZT-33IK 2024-11-20 23:12:31 56*60 0.74066 R 20.1 0.3 20.6 AS-32 The magnitudes were calibrated with nearby USNO-B1.0 stars (R2 magnitudes) and not corrected for the Galactic extinction. The source is 53 arcsec from the centre of IBIS/ISGRI localization. The catalogued source is a galaxy with estimated photo-z = 0.36 and brightness of r=20.2 (SDSS DR16), and photo-z = 0.38 (DESI). The source brightness in PS1 is r = 20.69. We may suggest the source is a possible candidate in the afterglow of GRB 241120A. View this GCN Circular online at https://gcn.nasa.gov/circulars/38291. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...