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