TITLE:   GCN CIRCULAR
NUMBER:  34356
SUBJECT: GRB 230805B : OHP/T193 optical upper limit
DATE:    23/08/07 13:34:31 GMT
FROM:    Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>

D. Turpin (CEA Paris-Saclay), C. Adami (LAM), B. Schneider (MIT),
E. Le Floc'h, D. Götz, F. Schüssler (CEA Paris-Saclay), A. de Ugarte Postigo (OCA/CNRS),
S. Basa (LAM), S. D. Vergani (GEPI, Obs. de Paris), report on behalf
of a larger collaboration:

We observed the field of GRB 230805B (Cenko et al., GCN 34339; D'Ali et al.,
GCN 34345; LaPorte et al., GCN 34251; Osborne et al. GCN 34353)
using the T193cm telescope at Observatoire de Haute-Provence (France)
equipped with the MISTRAL spectro-imager. In 5 exposures, obtained
in the r-band (5x600s) from 2023 05 August 20:36:08 UT to
21:34:34 UT (mid-time ~9.69h after trigger) under poor seeing conditions,
we do not detect any source at the position reported by
Moskvitin et al., GCN 34343; Malesani et al., GCN 34346; Hu et al., GCN 34347
down to the following 5-sigma limit:

r > 21.5 mag (AB)

The photometric calibration was performed using nearby stars from
the PanSTARRS catalog and the magnitude is not corrected for Galactic
extinction.

We acknowledge the excellent support from Observatoire de Haute-Provence,
in particular Jean Balcaen for the MISTRAL observations and
the SOPHIE observer Lisa Altinier.