TITLE:   GCN CIRCULAR
NUMBER:  32271
SUBJECT: GRB 220623A: T193-OHP optical upper limit
DATE:    22/06/26 16:43:42 GMT
FROM:    Benjamin Schneider at CEA  <benjamin.schneider@cea.fr>

B. Schneider, D. Turpin, E. Le Floc’h (CEA), C. Adami, 
S. Basa (LAM), S. Vergani, J. Palmerio (GEPI) 
report on behalf of a larger collaboration:

We observed the field of GRB 220623A (Sbarufatti et al. GCN 32243; 
Gopalakrishnan et al. GCN 32246; Ursi et al. GCN 32247) using 
the T193cm telescope at Observatoire de Haute-Provence (France) 
equipped with the MISTRAL spectro-imager. Six exposures 
(1x300s + 5x600s) were obtained in the i band using the red MISTRAL 
set-up from 2022 23 Jun 21:32:10 UT to 2022 23 Jun 23:05:49 UT 
(mid time ~15.2h after trigger). Data reduction is still preliminary. 
In the combined frame, we do not detect any source within the 2.2 arsec
error circle of the enhanced XRT position (Evans et al. GCN 32248; 
Beardmore et al. GCN 32248) down to the following 3-sigma limit:

i > 21.5 mag (AB)

The photometric calibration was performed using nearby stars 
from the PanSTARRS catalog.

We acknowledge the support from Observatoire de Haute-Provence, 
in particular Jean-Pierre Troncin and Jerome Schmidt.