TITLE:   GCN CIRCULAR
NUMBER:  32360
SUBJECT: GRB 220708B: T193-OHP optical upper limit
DATE:    22/07/10 20:54:34 GMT
FROM:    Damien Turpin at NAOC (CAS)  <dturpin-astro@hotmail.com>

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

We observed the field of GRB 220708B (Tohuvavohu et al. GCN 32345,
Kobayashi et al. GCN 32356, Frederiks et al. GCN 32358) using the T193cm
telescope at Observatoire de Haute-Provence (France) equipped with the 
MISTRAL spectro-imager. Six exposures (6x600s) were obtained in the r band
using the bleu MISTRAL set-up from 2022 08 Jul 20:55:39 UT to 2022 08 Jul
22:14:27 UT (mid time ~19.5h after trigger). In the combined frame, we do not
detect any source within the 4 arcsec error circle of the XRT position 
(Osborne et al. GCN 32350) down to the following 3-sigma limit:

r > 22.3 mag (AB)

The photometric calibration was performed using nearby stars 
from the PanSTARRS catalog. The magnitude is not corrected 
for Galactic extinction and it is consistent with the non-detections 
reported by Jiang et al. (GCN 32355).

We express our deepest thanks to the Observatoire de Haute-Provence for its
support, in particular to Stéphane Favard and Jérôme Schmitt.