{
  "createdOn": 1682072841650,
  "subject": "GRB 230420A: NOT optical afterglow confirmation",
  "bibcode": "2023GCN.33665....1F",
  "eventId": "GRB 230420A",
  "body": "S.Y. Fu (NAOC), K.E. Heintz (DAWN/NBI), D.B. Malesani (Radboud, DAWN/NBI), D. Xu (NAOC), M. Linares (NTNU & UPC), M. Turchetta (NTNU) report on behalf of a larger collaboration:\n\nWe observed the field of GRB 230420A detected by Swift (Klingler et al., GCN 33658) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 00:31:32 UT on 2023-04-21, i.e., ~14.2 hr after the Swift/BAT trigger, and 3 x 300 s images in the Sloan r-filter and 5 x 200 s images in the Sloan z-filter were obtained, respectively.\n\nWe detect an uncatalogued source in the stacked images within the enhanced XRT error circle (Osborne et al., GCN 33661) at coordinates:\n\nR.A. (J2000) = 10:44:11.55\nDec. (J2000) = +32:06:28.34\n\nwith an uncertainty of ~0.3 arcsec. The source has m(r) = 23.2 +/- 0.2 (AB) at 14.34 hr post-burst and m(z) = 22.3 +/- 0.2 (AB) at 14.64 hr post-burst, calibrated with nearby field stars from the Pan-STARRS catalog.\n\nThis source is likely the same as the one observed by BOOTES-5/JGT (Hu et al., GCN 33663), as both sources lie within the very small XRT error circle. The fading confirms that this source is the optical afterglow of GRB 230420A.\n\n",
  "submitter": "Dong Xu at NAOC/CAS <dxu@nao.cas.cn>",
  "circularId": 33665
}