TITLE: GCN CIRCULAR NUMBER: 44152 SUBJECT: EP260329a: NOT optical counterpart candidate DATE: 26/03/30 06:09:01 GMT FROM: L. B. He at NAOC <helb@bao.ac.cn> L.B. He, S.Q. Jiang, Z.P. Zhu, J. An, X. Liu, D. Xu (NAOC), S.Y. Fu (HUST), J. P. U. Fynbo (DAWN/NBI), K. Valeckas (NOT) report: We observed the field of EP260329a detected by Einstein Probe (EP), using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. We obtained 3 x 300 s frames in the Sloan r-band. An uncatalogued optical source is detected within the EP-WXT error circle (Yang et al., GCN 44141) at coordinates R.A. (J2000) = 5.4770 (deg) Dec. (J2000) = 82.4894 (deg) with an uncertainty of ~ 0.5 arcsec. The source has r ~ 21.6 mag (AB) at a median time of 45 mins after the EP trigger, calibrated with nearby PanSTARRS1-dr2 catalog and not corrected for Galactic extinction. No source is present at the above position in PanSTARRS down to a 5-sigma limit of r ~22.3 mag. No NEO object would be at the above position at the NOT observational time by checking MPC. We thus think the source could be the optical counterpart of EP260329a. View this GCN Circular online at https://gcn.nasa.gov/circulars/44152. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...