GCN Circular 45878
Subject
GRB261007A: Lesedi optical afterglow detection
Event
Date
2026-10-09T16:06:29Z (2 days ago)
From
reikantseone diretse at University of Cape Town <reikantseone01@gmail.com>
Via
Web form
R. Diretse (UCT, SARAO), P.J. Groot (Radboud, UCT, SAAO), S. de Wet (DTU Space), N. Erasmus (SAAO), W.X. Li (NAOC), N.C. Sun (UCAS,NAOC) report:
Using the SAAO 1-m Lesedi telescope located at Sutherland, South Africa, equipped with the Mookodi low-resolution spectrograph and imager, we obtained 4*180 s r,g exposures of the SVOM GRB261007A (Hatsune Goto et al., GCN 45824), starting at 2026-10-07T18:58:25.06 UTC, 13.27 hr post SVOM trigger. We detect the optical counterpart reported by (Zheng et al., GCN 45825) using the KAIT, by (W.F. Wen et al. 2026, GCN 45828) using the Einstein Probe, and (A. Saccardi et al. 2026, GCN 45829) using the ESO Very Large Telescope, measuring a spectroscopic redshift of z = 2.101.
We report:
r = 20.62 +/- 0.12 mag at 2026-10-07T18:58:25.06 UTC
g = 20.99 +/- 0.11 mag at 2026-10-07T19:02:03.42 UTC
These AB magnitudes are calibrated against the GAIA DR3 catalogue and are not corrected for galactic extinction.
Data was taken with the SAAO's 1-m Lesedi robotic telescope with the Mookodi low-resolution spectrograph and imager [1] as part of the SAAO "IO" rapid follow-up program [2]. We thank the SAAO IO team members including N. Erasmus, S. Potter, C. van Gend, H. Worters, S. Chandra, D. Cunnama, M. Hlakola, P. Rabe, R. Julie for making these observations possible.
[1] https://doi.org/10.1117/1.JATIS.10.2.025005
[2] https://doi.org/10.1117/12.3015250