GCN Circular 42547
Subject
GRB 251025B: OHP/T193 optical upper limit
Event
Date
2025-11-03T11:58:59Z (a day ago)
From
Christophe Adami at LAM <christophe.adami@lam.fr>
Via
Web form
C. Adami (LAM/Pytheas/AMU), N.A. Rakotondrainibe (LAM), B. Schneider (LAM), F. Destriez (OBSPM), Y. Degot-Longui (OHP/Pytheas) report on behalf of the MISTRAL GRB collaboration:
We carried out observations of GRB 251025B (Hussein et al., GCN 42437) afterglow (Wu et al., GCN 42438; Gress et al., GCN 42439; Wu et al., GCN 42440; Beardmore et al., GCN 42445; Mohan et al., GCN 42447; Hernández Funget al., GCN 42450; Pereyra et al., GCN 42452; Li et al., GCN 42453; Mo et al., GCN 42459; Rakotondrainibe et al., GCN 42460; Rajabov et al., GCN 42466; Saccardi et al., GCN 42472; Turpin et al., GCN 42474; Volnova et al., GCN 42475; Evans et al., GCN 42493; Gupta et al., GCN 42500; Swain et al., GCN 42503) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 23 exposures of 5 min and 2 exposures of 3min in the r-band at a midtime of 2025-11-02 22:44:40 UT, corresponding to T-T0 = 200.342hours.
We do not significantly detect the afterglow at a 3-sigma upper limit of:
r’ < 22.37 mag (AB)
The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction. We used the STDWeb/STDPipe tools (Karpov 2025).
We acknowledge the excellent support from the Observatoire de Haute-Provence.