{
  "bibcode": "2005GCN..3171....1D",
  "body": "P. D'Avanzo, D. Fugazza (INAF-OAB), N. Masetti (INAF-IASF, Bologna) and\nM. Pedani (TNG), on behalf of a larger collaboration, report:\n\n\n\"We have obtained R-band photometry of the optical afterglow (McNaught &\nPrice, GCN #3163; Rykoff et al., GCN #3165) of GRB050401 (Angelini et al.,\nGCN #3161; Barbier et al., GCN #3162) using DOLoRes at TNG.\nThe observations, for a total exposure time of 30 minutes, were performed\nunder moderate seeing conditions (around 1.2 arcsec).\n\nA preliminary analysis of the images allowed us to derive the following\nphotometry for the OT, calibrated after observing the SA104 Landolt\nstandard field:\n\nR = 23.18 +/- 0.10  on 2005 April 2.072 UT, 11.39 hours after the burst\n\nUsing this OT magnitude and those reported in GCNs #3163 and #3165, and \nassuming a canonical power-law decay, we obtain for the OT a decay index \nalpha ~ 1, quite typical of GRB optical afterglows.\n\nWe are particularly grateful to the TNG staff for their remarkable support \nto these observations.\"\n\nThis message is citeable.",
  "circularId": 3171,
  "createdOn": 1112441812000,
  "email": "masetti@bo.iasf.cnr.it",
  "subject": "GRB050401: TNG R-band observation",
  "submitter": "Nicola Masetti at IASF,CNR,Bologna  <masetti@bo.iasf.cnr.it>",
  "eventId": "GRB 050401"
}