{
  "bibcode": "2024GCN.37035....1A",
  "body": "J. An, S.Y. Fu, S.Q. Jiang, X. Liu, Z.P. Zhu, D. Xu (NAOC), J.P.U. Fynbo (DAWN/NBI), B.N. Hauptmann (NOT) report on behalf of a large collaboration:\n\nWe observed the field of EP240804a detected by Einstein Probe (EP, Wang et al., GCN 37034), using the ALFOSC instrument mounted on the Nordic Optical Telescope (NOT), with 3x300 s photometry in the SDSS-r band. Observations started at 02:55:25 UT on 2024-08-05, i.e. 5.28 hr after the trigger.\n\nAn uncatalogued decaying source is detected in the individual as well as the stacked frames within the EP/FXT error circle (Wang et al., GCN 37034) and localized at coordinates\n\nR.A. (J2000) = 22:30:38.84\nDec. (J2000) = -39:07:20.06\n\nwith an uncertainty of ~ 0.5 arcsec. The source has r ~ 20 mag, calibrated with SkyMapper and not corrected for Galactic extinction. There is no known object at the above position by checking MPC.\n\nWe thus conclude that the source is the optical counterpart candidate of EP240804a.\n\nFurther observations are encouraged.\n\n",
  "submitter": "Zipei Zhu at NAOC <zpzhu@nao.cas.cn>",
  "createdOn": 1722834441281,
  "eventId": "EP240804a",
  "submittedHow": "email-legacy",
  "circularId": 37035,
  "subject": "EP240804a: NOT optical counterpart detection"
}