TITLE: GCN CIRCULAR NUMBER: 39476 SUBJECT: EP250223a: GMG Optical Observation DATE: 25/02/26 04:26:24 GMT FROM: Boting Wang at Yunnan Observatories, CAS wangbaiting@ynao.ac.cn

B.-T. Wang, R.-Z. Li, F.-F. Song, J. Mao, D.-Q. Wang, and J.-M. Bai (YNAO, CAS) report:

We observed the field of EP250223a (Lian et al., GCN 39429, T0 at 2025-02-23T15:04:35.749) using the GMG-2.4m telescope at the Lijiang Observatory. The observation began at 2025-02-25T12:45:36.92, about 45.68 hours after the trigger. The optical counterpart of EP250223a (Hauptmann et al., GCN 39436; Wu et al., GCN 39439; Pérez-Fournon et al., GCN 39440; Izzo et al., GCN 39441; Xin et al., GCN 39445; Guo et al., GCN 39447; An et al., GCN 39449; Ducoin et al., GCN 39453; O’Neill et al., GCN 39455; Aryan et al., GCN 39464; Saikia et al., GCN 39472), with a redshift of 2.756 (Levan et al., GCN 39438), was detected within the error box of EP/FXT (Lian et al., GCN 39429).

The preliminary analysis results are shown as follows: | tmid-t0 (hours) | Filter | Exposure (s) | Magnitude (AB) | 5-sigma U.L. | | ----------- |------- | ------------------ | -------------- | ------ | | 45.85 | sdssr | 1200 | 20.82 +/- 0.08 | 21.9 |

The given magnitudes are derived based on calibration against Pan-STARRS1 field stars and are not corrected for the expected Galactic foreground extinction.

We warmly thank the staff at the Lijiang Observatory for their efforts in conducting the observation.

View this GCN Circular online at https://gcn.nasa.gov/circulars/39476. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...