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GCN Circular 36841

Subject
EP240708a: SVOM/C-GFT optical upper limit
Date
2024-07-10T14:15:39Z (9 days ago)
From
Chao Wu at NAOC <wuchao.lamost@gmail.com>
Via
legacy email
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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