TITLE:   GCN CIRCULAR
NUMBER:  33734
SUBJECT: GRB  230506C: TSHAO possible afterglow candidate
DATE:    23/05/06 23:13:08 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

N. Pankov (HSE), I. Reva (FAI), A. Pozanenko (IKI),  S. Belkin (IKI)  report on behalf of GRB-IKI-FuN:

We observed the field of  GRB 230506C detected by Swift (Tohuvavohu et al., GCN  33731)  with Zeiss-1000 telescope of Tien Shan Astronomical Observatory stating on May, 06 (UT) 17:24:54 in R-filter.

Within Swift-BAT error circle (Tohuvavohu et al., GCN  33731)  we  detected uncatalogued object in coordinates of (J2000) 08:57:28.13 +45:07:59.48 with uncertainties of 0.3 arcsec in each coordinate.  The object is absent in SDSS images. A distance of the object from the center of BAT error circle is ~30 arces. Preliminary photometry of a stacked images is following

Date       UT start t-T0    Filter  Exp.    OT     Err.  UL(3 sigma)
                    (mid, days)     (s)

2023-05-06 17:24:54 0.02914  R      23*120  20.1  0.1  21.5
 
The photometry is based on nearby USNO-B1.0 stars.
We suggest that the object is a candidate for the afterglow of GRB 230506C.