GCN Circular 36761
Subject
EP240625a: NOT optical counterpart candidate
Date
2024-06-25T16:25:42Z (3 months ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Via
Web form
S.Y. Fu, J. An, S.Q. Jiang, X. Liu, Z.P. Zhu, D. Xu (NAOC), J.P.U. Fynbo (DAWN/NBI), N. Koivisto (NOT) report on behalf of a large collaboration:
We observed the field of EP240625a detected by EP/WXT (Pan et al., GCN 36757) using the the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. We obtained 16x30 s Sloan z-filter images at a median time of 1.52 hr after the EP trigger.
An uncatalogued optical transient (OT), within the 10 arcsec EP/FXT error circle (Pan et al., GCN 36760), is marginally detected in the stacked z-band image at coordinates:
R.A. (J2000)= 20:42:55.47
Dec. (J2000)= -15:58:24.00
with an uncertainty of ~ 0.2 arcsec. It has z = 20.7 +/- 0.2 mag , calibrated against nearby Pan-STARRS stars and not corrected for Galactic extinction. Given the low S/N for the OT, we cannot completely rule out it being due to background fluctuation.
Further observations are scheduled.