TITLE:   GCN CIRCULAR
NUMBER:  37271
SUBJECT: GRB 240824A: SVOM/C-GFT optical upper limit
DATE:    24/08/25 14:38:45 GMT
FROM:    Chao Wu at NAOC <wuchao.lamost@gmail.com>

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,  China), Bertrand Cordier (CEA, F),
Shuang-Nan Zhang (IHEP, CN), Stephane  Basa (LAM, F), Jean-Luc Attéia
(IRAP, F), Arnaud Claret (CEA, F),  Zi-Gao Dai (USTC, CN), Frederic
Daigne (IAP, F), Jin-Song Deng (NAOC,  CN), Andrea Goldwurm (APC, F),
Diego  Götz (CEA, F), Xu-Hui Han (NAOC, CN), Cyril Lachaud (APC, F),
En-Wei Liang (GXU, CN), Yu-Lei Qiu (NAOC,  CN), Susanna Vergani (Obs.
Paris, F), Jing Wang (NAOC, CN), Chao Wu(NAOC, CN), Li-Ping Xin (NAOC,
CN), Bing Zhang (UNLV, CN)

We observed the field of the Swift GRB 240824A (Cenko et al., GCN
37254) starting at 11:02:55UT, August 24, 2024, ~10 hr after the burst
with C-GFT (Chinese Ground Follow-up Telescope in SVOM mission) in
System Test Mode (STM). 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 series of g ,r,and i band images were obtained. We obtained stacked
images of r: 245 x 10s,g: 255 x 10s and i:234 x 10s. No optical
afterglow was detected for the candidate reported by Evans (GCN 37269)
down to the limit magnitude of mag_g=20.6 , mag_r=20.5, and
mag_i=20.0.

The photometry was calibrated with  UCAC4 catalogs.

We thank the observation assistant Bowen Li at Jilin observatory for
their excellent support.