TITLE:   GCN CIRCULAR
NUMBER:  37365
SUBJECT: GRB240828B: REM optical/NIR upper limits
DATE:    24/08/31 18:52:21 GMT
FROM:    Riccardo Brivio <riccardo.brivio@inaf.it>

R. Brivio, M. Ferro, P. D’Avanzo, M.G. Bernardini, S. Campana, S. Covino, D. Fugazza, E. Molinari, Y.-D. Hu (INAF-OAB) report on behalf of the REM team:

We observed the field of the soft GRB 240828B detected by SVOM/ECLAIRs (Le Provost et al., GCN 37318) with the REM 60cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, H bands, starting on 2024 August 31 at 06:19:52 UT (i.e. 2.71 days after the SVOM trigger), and lasting for about 1 hour.

From preliminary photometry we do not detect any optical/NIR counterpart at the Swift-XRT position (Page et al., GCN 37334) down to the following 3sigma magnitude upper limits:

H > 15.7 
(Vega; calibrated against the 2MASS catalogue)

r > 19.9
(AB; calibrated against the PanSTARRS catalogue)

at a mid-time of t - t0 = 2.73 days after the trigger.