{
  "bibcode": "2009GCN.10185....1D",
  "body": "P. D'Avanzo (INAF-OAB), L.A. Antonelli (INAF-OAR), A. de Ugarte Postigo\n(INAF-OAB), A.J. Castro-Tirado (IAA-CSIC), J. Gorosabel (IAA-CSIC), E.\nPalazzi (IANF-IASFBo), S. Covino (INAF/OAB), J.M. de Leon Cruz,\n(IAA-CSIC), C. Padilla (TNG) report:\n\nWe observed the field of GRB 091117 (Cummings et al. GCN 10171) with the\nItalian 3.6m TNG telescope, sited in Canary Islands (Spain) with the\nDOLORES camera in imaging mode on Nov 19.995 UT. Observations were carried\nout in V, R and I band.\n\nWe compared our 900 s I-band image with the one obtained in the same band\nwith the 1.5m OSN telescope on Nov 18.9 UT (Casanova et al., GCN 10172).\nImage subtraction performed with the ISIS package does not show any\nvariable source in the overlap region covered by the two images (about 90%\nof the BAT error circle; Sakamoto et al, GCN 10180). In particular we note\nthat no variability is detected for XRT source #1 (Berger, GCN. 10173;\nD'Elia et al., GCN 10177; Fox, GCN 10179) while no conclusion can be drawn\nfor XRT source #2 (D'Elia et al., GCN 10177; Fox, GCN 10179) because it is\nsaturated in the TNG image.\n\nAn image showing the result of image subtraction is available here:\nhttp://www.brera.inaf.it/utenti/davanzo/grb/GRB091117_subtraction.jpg\n\nThe 3sigma limiting magnitudes are I~22.9 and I~23.6 for the OSN and TNG\nimages respectively.",
  "circularId": 10185,
  "createdOn": 1258766663000,
  "email": "paolo.davanzo@brera.inaf.it",
  "subject": "GRB 091117: TNG optical observations",
  "submitter": "Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>",
  "eventId": "GRB 091117"
}