GCN Circular 37720
Subject
GRB 240930B: SVOM/C-GFT optical upper limit
Date
2024-10-06T12:15:20Z (5 months ago)
From
Chao Wu at NAOC <cwu@nao.cas.cn>
Via
Web form
SVOM/C-GFT team: Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC),Olivier Godet (IRAP), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Shao-Lin Xiong (IHEP), Bing Zhang (UNLV)
We observed the field of GRB 240930B/EP240930a by Fermi/GBM (Fermi GBM Team, GCN 37640; Smith & Meegan, GCN 37660), EP/WXT (Tian et al., GCN 37648), Swift/BAT (DeLaunay et al., GCN 37654), GRBAlpha (Dafcikova et al., GCN 37658), CALET/GBM (Shimizu et al., GCN 37691), HEND/Mars Odyssey, Konus-Wind, INTEGRAL SPI-ACS (Kozyrev et al., GCN 37696), and SVOM/GRM (Wang et al., GCN 37714) starting at 2024-10-01T11:41:08 UT, ~ 18.39 hr after the burst trigger with C-GFT (Chinese Ground Follow-up Telescope in SVOM mission) in the commissionig phase. C-GFT is located at Jilin (long.=126.33 deg, lat.= 43.8243778 deg), Changchun Observatory, National Astronomical Observatories, CAS. It has FOV of 1.28 deg x 1.28 deg with a 4k*4k CMOS detector mounted on the primary focus of 1.2-meter-aperure telescope.
A set of 61x30s iamges were obtained in g, r, and i band. No any optical counterpart detected within the EP-FXT source error circle (Peng et al., GCN 37653) down to the limiting magnitude (3 sigma) of mag_g=20.58, mag_r=20.33, mag_i=20.01 for stacked image. It is consistent with the results reported by Zheng et al. (GCN 37656) and Bochenek & Perley (GCN 37682).
The photometry was calibrated with nearby stars in Pan-STARRS 1 .
We thank the observation assistant Guo Chunlei at Jilin observatory for their excellent support.