{
  "bibcode": "2004GCN..2788....1D",
  "body": "P. D'Avanzo, S. Covino, L.A. Antonelli, D. Fugazza, D. Malesani, F. \nFiore, F. Cocchia, N. Masetti, E. Pian, L. Stella (on behalf of the \nItalian CIBO collaboration); V. Lorenzi and R. Barrena (INAF-TNG), report:\n\nWe observed again the optical afterglow (Da Costa, Noel & Price, GCN \n2765; Maeno et al. GCN 2772) of GRB 041006 (Galassi et al., GCN 2770) \nwith TNG. Photometry was performed in the UBVRI bands under good \nobserving conditions (seeing 1.2\").\n\nWe measure the following magnitude for the afterglow on Oct 8.10 UT \n(1.59 days after the GRB):\n\nR = 22.12 +/- 0.08\n\nA comparison with our previous measurement (Fugazza et al., GCN 2782) \nimplies a dimming of 1.36 +- 0.09 mag. The corresponding decay index is \nalpha = 1.20 +- 0.08 (F = K t^-alpha), significantly steeper than the \nearly-time value (alpha ~ 0.7: Fox, GCN 2768; Price, Da Costa & Noel, \nGCN 2771; Yost et al., GCN 2776). A break in the light curve must \ntherefore be present, consistent with the suggestion of Kahharov et al. \n(GCN 2775). The fading is confirmed in the other bands and is achromatic \nwithin the errors.\n\nWe also observed again Landolt standard stars, finding the same \nzeropoint than in our previous observation (Fugazza et al., GCN 2782) to \nwithin 0.03 mag. We conclude that our calibration is correct and both \nnights were photometric.\n\nThe light curve of this event, including all the published photometry, \ncan be found at the following URL:\n\nhttp://www.sissa.it/~malesani/GRB/041006\n\nThis message can be cited.",
  "circularId": 2788,
  "createdOn": 1097260462000,
  "email": "malesani@sissa.it",
  "subject": "GRB041006: break in the light curve",
  "submitter": "Daniele Malesani at SISSA-ISAS,Trieste,Italy  <malesani@sissa.it>",
  "eventId": "GRB 041006"
}