TITLE: GCN CIRCULAR NUMBER: 39612 SUBJECT: EP250302a:Xinglong optical observations DATE: 25/03/07 09:55:58 GMT FROM: Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) xinglong@nao.cas.cn
Junjie-Jin (NAOC), Haiyang-Mu (NAOC), Jinlei-Zhang (NAOC), Pengliang-Du (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report: We performed optical observations of the field of a fast X-Ray transient EP250302a (Zhu et. al, GCN 39550; ) in the g, i and r filter using Tsinghua-NAOC 0.8-m telescope (TNT) located at Xinglong, Hebei, China. In each band a 600 s exposures were taken , with a median observation time of 2025-03-02T20:32:28, approximately 5 hours after the EP FXT trigger (2025-03-02T15:36:04). The optical object reported by Zhu et al. (GCN #39550) is detected in our image. We measure a preliminary magnitude of g = 17.98 +/- 0.46, i = 18.64 +/- 0.42 and r=18.41+/- 0.56 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 | 2025-03-02T16:46:26.6 | 600 s | g |17.98 +/- 0.46| Tsinghua-NAOC 0.8-m telescope (TNT)
2 | 2025-03-02T17:06:50.4 | 600 s | i |18.64 +/- 0.42| Tsinghua-NAOC 0.8-m telescope (TNT)
3 | 2025-03-02T16:46:26.6 | 600 s | r |18.41 +/- 0.56| Tsinghua-NAOC 0.8-m telescope (TNT)
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