TITLE:   GCN CIRCULAR
NUMBER:  35744
SUBJECT: GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
DATE:    24/02/18 05:10:36 GMT
FROM:    Emeric Le Floc'h at CEA-Saclay <emeric.lefloch@cea.fr>

C. Adami (LAM) and E. Le Floc'h (CEA-Saclay) report on behalf of the MISTRAL GRB collaboration:

We observed the field of GRB 240218A (Page et al., GCN 35742) using the MISTRAL spectro-imager mounted on the T193 telescope at Observatoire de Haute-Provence (France). We obtained a sequence of 5 images (5min, 10min, 3x15min) for an observation mid-time corresponding to 67min after the GRB) and a total observing time of 1h. Similar to the non detection reported earlier by Malesani et al. (GCN 35743), we did not detect any afterglow candidate consistent with the XRT position, down to the following upper limit :

r > 23 (AB)

The photometry was calibrated against the PanStarrs catalog within a circle of 2’ (radius) around the GRB position.

 We acknowledge excellent support from Observatoire de Haute Provence, in particular Yoann Degot Longhi.