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GCN Circular 36841

EP240708a: SVOM/C-GFT optical upper limit
2024-07-10T14:15:39Z (9 days ago)
Chao Wu at NAOC <>
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Chao Wu (NAOC),  Xuhui Han (NAOC),  Zhe Kang (CHO), Liping Xin (NAOC),
Pinpin Zhang (NAOC),Xiaomeng Lu (NAOC), Zhenwei Li (CHO),Ruosong Zhang
(NAOC),Yujie Xiao(NAOC),  Yulei Qiu (NAOC),You  Lv (CHO),Jing
Wang(GXU/NAOC), and Jianyan Wei (NAOC) on behalf of SVOM GRB team

We observed the field of the fast X-ray transient EP240708a (Chen et al.,
GCN 36838) on 18:00:53 UT, July, 9th, 2024, about 18.54 hours after the
Einstein Probe (EP) mission trigger 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. The exposure time was
12*10 seconds for each band.

No optical afterglow was detected within the enhanced FXT error box (Hu et
al., GCN 36840) down to a limit magnitude of 18.2,18.9 and 18.9 for g,r,and
i band respectively, which was consistent with the report (Lai et al.,
36839; ) at a similar time range.

The photometry was calibrated with nearby UCAC 4 catalogs.

We thank the observation assistant Guangsheng Zhang at Jilin observatory
for their excellent support.

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