{
  "bibcode": "2007GCN..6674....1M",
  "body": "D. Malesani, J.P.U. Fynbo, P.M. Vreeswijk (DARK), I. Ilyn (AIP), report \non behalf of a larger collaboration:\n\nWe observed the field of GRB 070721A (Ziaeepour et al., GCN 6639) in two \ndifferent epochs, using the NOT and VLT telescopes. Observations were \ncarried out 0.78 and 1.98 days after the GRB. A bright star (R~17.3) is \nclose to the XRT position (Evans & Ziaeepour, GCN 6640). Inside the XRT \nerror circle, we detect a single source at the coordinates (J2000, \nagainst USNO-B1):\n\n  RA = 00:12:39.13\n  Dec = -28:33:00.9\n\nThis source does not vary between the two epochs to within 0.2 mag, and \nis pointlike under seeing conditions of 0.7\". We measure R~22.9 using \nVLT instrumental zeropoints (~0.1 mag error). No other sources are seen \ninside the XRT error circle down to the limits reported below.\n\nMean UT       T-T0 (d)  t_exp (s) Instrument  Rlim\n--------------------------------------------------\nJul 22.20065  0.78320   4x600     NOT+StanCam 24.0\nJul 23.39637  1.97892   2x180     VLT+FORS2   25.5\n\nT0 = trigger time = Jul 21.41745 UT.\n\nThis message can be cited.",
  "circularId": 6674,
  "createdOn": 1185556486000,
  "email": "malesani@astro.ku.dk",
  "subject": "GRB 070721A: optical observations",
  "submitter": "Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center  <malesani@astro.ku.dk>",
  "eventId": "GRB 070721A"
}