GCN Circular 39687
Subject
GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
Date
2025-03-12T17:01:44Z (a day ago)
Edited On
2025-03-12T17:12:22Z (a day ago)
From
sqjiang at NAOC <sqjiang@bao.ac.cn>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of sqjiang at NAOC <sqjiang@bao.ac.cn>
Via
Web form
S.Q. Jiang (NAOC), S.H. Wang (THU), J. An, X. Liu, Z.P. Zhu, D. Xu (NAOC), S.Y. Fu (HUST), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the optical counterpart AT2025dws (Stein et al., GCN 39639, 39644; Pérez-Fournon et al., GCN 39643; Moskvitin et al., GCN 39645, 39658; Perley et al., GCN 39646; Malesani et al., GCN 39647; Page and Evans, GCN 39649; Ducoin et al., GCN 39650; Shin et al., GCN 39654; Wang et al., GCN 39661; Guiffreda et al., GCN 39670) of GRB 250309B (GBM team, GCN 39635; Preis and Greiner, GCN 39629; McDermott et al., GCN 39642; Wang et al., GCN 39648; Kozyrev et al., GCN 39652; Frederiks et al., GCN 39655), using the 0.33 m diameter telescope RC-10 located at Daochen, Sichuan, China. Observations started at 18:53:25.836 on 2025-03-09, i.e., 11.247 hrs after the Fermi/GBM trigger time, a series of 600 s frames in sloan r-band were obtained.
The optical transient was detected in our stacked image with mag_r= 19.7 +/- 0.2 at a median time of 12.260 hrs after the trigger time, calibrated with the nearby Pan-STARRS field and not corrected for Galactic extinction.