TITLE:   GCN CIRCULAR
NUMBER:  38607
SUBJECT: EP241217a: Xinglong optical follow-up observations
DATE:    24/12/18 07:04:57 GMT
FROM:    EP Team at NAOC/CAS <ep_ta@bao.ac.cn>

Junjie-Jin (NAOC), Yiming-Mao(NAOC), Jie-Zheng (NAOC), Haiyang-Mu(NAOC), Yinan-Zhu (NAOC), Qi-Zhao (NAOC), Feng-Xiao (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report:
We observed the field of the X-ray transient, EP 241217a by the Xinglong 0.8-m and 216 telescope located at Xinglong, Hebei, China.
We obtained 6 x 600 s clear-band by 0.8-m telescop with a median time of 2024-12-17T10:12:27 , i.e., 5.5 hr after the EP trigger. We detected no optical object with the upper limit ～21 mag. Then we performed photometry on the Xinglong 2.16-m telescope located at Xinglong, Hebei, China, and obtained 6x600s clear-band frames with a median time of 2024-12-17T16:50:08 , i.e., 12 hr after the EP trigger. The optical object reported by Levan et al. (GCN #38587) is weakly detected in our image. We measure a preliminary magnitude of r = 21.4 +/- 0.14 mag (AB), calibrated against nearby stars from the Pan-STARRS catalog.

We summarize our observation results as follows:

Obs. No. | Time (UTC)        | Exposure Time (s) | Filter | Apparent mag (AB) | Telescope Name

1      | 2024-12-17 10:12:27 | 6x600 s        | Clear |> 21.0           | Xinglong 80-cm Telescope

2      | 2024-12-17 16:50:08 | 6x600 s        | Clear | 21.4 +/- 0.14   | Xinglong 2.16-m Telescope