{
  "bibcode": "2020GCN.27222....1A",
  "body": "J. F. Agui Fernandez, M. Blazek, D. A. Kann (all HETH/IAA-CSIC), A. de \nUgarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene (HETH/IAA-CSIC), \nE. Gallego-Cano, and A. Guijarro (both CAHA) report:\n\nWe observed the field of the Swift-detected GRB 200224A (Ukwatta et al., \nGCN #21173) with the 2.2m telescope at CAHA, Almeria, Spain. We obtained \n5 x 120 s each in Rc and Ic.\n\nAt the position of the optical afterglow reported by Sota et al. (GCN \n#27176), Stecklum et al. (GCN #21177), and Marshall & Ukwatta (GCN \n#27182), we clearly detect a source in each stack image.\n\nWe measure Rc = 21.60 +/- 0.06 mag at 0.03702 days after the GRB, and Ic \n= 21.31 +/- 0.09 mag at 0.05794 days after the GRB (Vega magnitudes), in \ngood agreement with the measurements of Tautenburg at an earlier time \n(GCN #27177) and OSN at a later time (GCN #27176).\n\nWe note the optical afterglow is very faint (see also Becerra et al., \nGCN #27189), but the clear detection in u by Swift/UVOT (GCN #27182) as \nwell as the blue Rc-Ic color we find indicates this GRB is neither at \nhigh redshift nor particularly extinguished (see also the XRT results, \nGropp et al., GCN #27179), it is likely just intrinsically faint.",
  "circularId": 27222,
  "createdOn": 1582714059000,
  "email": "kann@iaa.es",
  "subject": "GRB 200224A: Calar Alto 2.2m optical afterglow detection",
  "submitter": "Alexander Kann at IAA-CSIC  <kann@iaa.es>",
  "eventId": "GRB 200224A"
}