TITLE:   GCN CIRCULAR
NUMBER:  40939
SUBJECT: GRB 250702F: optical photometry from Konkoly
DATE:    25/07/04 08:55:20 GMT
FROM:    Jozsef Vinko at Konkoly Observator <vinko@konkoly.hu>

GRB 250702F: optical photometry from Konkoly 

J. Vinko, K. Sarneczky, A. Horti-David, R. Konyves-Toth, Zs. Bora, L. Kriskovics, A. Pal, R. Szakats 
(Konkoly Observatory, Hungary) 

We report detection and photometry of the optical afterglow of GRB 250702F (Fermi GRB team, GCN 40892; Klinger et al. GCN 40894) taken with the RC80 robotic telescope at Piszkesteto Station of Konkoly Observatory, Hungary. The observations started on 2025-07-03 21:15:51 UT, 24.15 hours after the trigger. 5 sets of 300 sec frames were collected through Sloan g', r'- and i' bands. 

The optical afterglow (Klingler et al., GCN 40894; Jelinek et al., GCN 40895; Kumar et al., GCN 40896; Lipunov et al., GCN 40899; Martin-Carrillo et al., GCN 40900; de Ugarte Postigo et al., GCN 40901; Angulo et al., GCN 40907; Becerra et al., GCN 40911; Brivio et al., GCN 40913; An et al., GCN 40916; Dutton et al., GCN 40921; Odeh et al., GCN 40925; Moretti et al., GCN 40926; Siegel et al., GCN 40933; Ma et al. GCN 40936) was detected on the stacked frames with the following magnitudes, calibrated via nearby PS1 stars: 

Date UT-middle t-T0(days) Exp(s) g'(AB) r'(AB) i'(AB) 
2025-07-03 21:23:27.12 1.006 5x300 21.06 (0.26) 20.77 (0.18) 20.06 (0.15) 

The magnitudes above are not corrected for galactic extinction.