{
  "bibcode": "2007GCN..6574....1D",
  "body": "P. D'Avanzo (INAF - OABr) V. D'Elia (INAF - OAR), D. Fugazza,  G. \nTagliaferri (INAF - OABr) on behalf of the MISTICI collaboration and D. \nMalesani and J.P.U. Fynbo (DARK/NBI) report:\n\nWe observed the field of GRB070621 (Sbarufatti et al., GCN 6560) with \nthe ESO-VLT equipped with the FORS1 camera in the R and I bands. \nObservations were carried out on Jun 22.36 and 22.38 UT (0.39 and 0.41 \ndays after the GRB) in the I and R filters, respectively.\n\nWe detect two extended sources near the revised XRT error box \n(Sbarufatti et al. GCN 6569), reported by different authors (Malesani et \nal. GCN 6565, Tanvir et al. GCN 6570, Bloom et al. GCN 6568 and GCN \n6572), at the following coordinates (J2000):\n\nS1) R.A. = 21:35:10.08, Dec. = -24:49:07.5\nS2) R.A. = 21:35:10.27, Dec. = -24:49:02.8\n\nwith an uncertainty of 0.4\".\n\nA comparison between the NOT (Malesani et al. GCN 6565) and VLT images \nshows that source S1 remained constant between the NOT and VLT \nobservation up to 0.1 mag.\n\nSource S2 is not visible in the NOT image, so that a direct  comparison \nis not possible. When considering the roughly simultaneous WHT I-band \nmeasurement by Tanvir et al. (GCN 6570), we note a small discrepancy \n(~0.5 mag) in the magnitude of source S1. After taking into account this \nuncertainty, no variability can be claimed for source S2 as well.\n\nSource S1 appears elongated in the East/West direction, consistent with \nthe superposition of two objects as resolved in the adaptive-optics Keck \nimage (Bloom et al. GCN 6572).\n\nWe acknowledge the support of the ESO staff.\n\nThis message can be quoted.",
  "circularId": 6574,
  "createdOn": 1182537481000,
  "email": "paolo.davanzo@brera.inaf.it",
  "subject": "GRB 070621: VLT optical observations",
  "submitter": "Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>",
  "eventId": "GRB 070621"
}