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GCN Circular 35167

GRB 231118A: REM optical afterglow detection
2023-11-23T13:57:31Z (3 months ago)
Paolo D'Avanzo at INAF-OAB <>
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R. Brivio, M. Ferro, P. D'Avanzo, D. Fugazza, S. Covino (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 231118A (Fermi GBM Team., GCN 35100; Laha et al., GCN 35101) with the REM 60cm robotic telescope located at the ESO Observatory of La Silla (Chile). The observations were carried out in the g, r, i, z, J, H and K bands, starting on 2023 Nov 19 at 00:16:39 UT (i.e. about 7.00 hours after the GBM and Swift trigger) and lasted for about 1 hour.

The optical afterglow (Dutton et al., GCN 35103, Strausbaugh et al., GCN 35110, Shrestha et al., GCN 35113, de Wet et al., GCN 35126, Takahashi et al., GCN 35133), is detected in r, i bands coadded frames (t_exp = 20 min) . From preliminary photometry, we derive the following magnitudes and limits:

r = 19.66 +/- 0.08 (AB)
i = 19.19 +/- 0.11 (AB; calibrated against the the APASS catalogue)
at a mid time of t-t0 ~ 7.68 hours after the GRB trigger.

H > 17.7 (Vega; calibrated against the 2MASS catalogue) 
at a mid time of t-t0 ~ 7.44 hours after the GRB trigger.

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