TITLE: GCN CIRCULAR NUMBER: 34867 SUBJECT: GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy. DATE: 23/10/21 11:22:19 GMT FROM: XXXX at IKI <alex@cgrsmx.iki.rssi.ru> S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE) report on behalf of GRB IKI FuN: We observed the field of GBM/Fermi and Swift/BAT-GUANO candidate of GRB 231017A (Fermi GCM Team GCN 34822; Mangan et al. 2023, GCN 34830; DeLaunay et al. 2023, GCN 34824; GCN 34825) with AZT-33IK telescope of Mondy observatory in R-filter on 2023-10-20 starting (UT) 18:02:43. We detect only one object within Swift-XRT X2 candidate error circle (Dichiara et al. GCN 34829) at coordinates of (J2000) 05:44:40.6245 +56:44:54.767. The object position is 5.3 arcsec apart from Swift-XRT center of the XRT X2 error circle. However, at the moment we cannot say about the variability of the object. We may propose the object as a candidate for an afterglow or host galaxy of GRB 230420A. Preliminary photometry of the object is following Date UT start t-T0 Exp. Filter OT Err. UL(3sigma) (mid, days) (s) 2023-10-20 18:02:43 3.43519 29x120 R 22.98 0.20 23.5 The photometry is based on nearby USNO-B1.0 R2 stars USNO-B1.0 RA DEC R2 05:44:36.1893600 +56:44:30.523200 15.96 05:44:49.0394400 +56:45:26.060400 16.24 05:44:55.8448800 +56:45:12.002400 16.30 05:44:44.9767200 +56:47:48.480000 16.48 View this GCN Circular online at https://gcn.nasa.gov/circulars/34867. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...