{
  "bibcode": "2005GCN..4264....1R",
  "body": "Nanda Rea (SRON), Elisa Costantini (SRON) and Gianluca Israel (INAF-OAR)\n\nreport:\n\nWe report on the preliminary analysis of a 27ks XMM-Newton ToO\nobservation of GRB 050925 (GCN 4034 Holland et al.; GCN 4037 Markwardt\net al.) performed on 2005 October 12. The very short (128 ms) duration\nof this GRB and the lack of any bright UV/Opt/IR afterglow (GCN 4038\nRosen et al.; GCN 4035 Guidorzi et al.; GCN 4036 Qiu et al.; GCN 4042\nBloom et al.) suggested a probable Soft Gamma-Ray Repeater (SGR)\nnature of this burst. A bright, seemingly not variable, radio source\nwas reported at 4.9 GHz, just outside the refined Swift-BAT error\ncircle (GCN 4039 and GCN 4057 van der Horst et al.).\n\nIn the Swift-BAT 1.5 arcminutes error circle of GRB 050925 (GCN 4037\nMarkwardt et al.) the XMM-PN detects only one source at RA: 20 13\n47.84, Dec: 34 19 52.0 (1.2 arcsec associated error circle; errors given \nat 90%). The Epic-PN source count rate is 0.022+/-0.001 counts/s.\nThis source is consistent with the one detected by the Swift-XRT (GCN\n4043 Beardmore et al.). The USNO object, previously consistent with\nthe XRT position, lies now outside the refined XMM error circle.\n\nA preliminary timing analysis does not show any significant periodic\nsignal. The source spectrum is soft and not well fitted by simple\nmodels as absorbed power-law, blackbody or bremsstrahlung\n(chi^2/dof=4.0, 2.8 and 3.1, respectively). The fit improves using two\ncomponents, power-law plus blackbody or two blackbodies (chi^2/dof=0.9). \nThe correspondent absorbed flux (4x10^-14 ergs*cm^-2*s^-1 in the\n0.5-10 keV band) is consistent with the XRT value.\nA detailed spectral analysis is on-going. As already noted in\nGCN 4043 by Page et al., the absorption value of this source\n(~10^21 cm^-2) is very low compared with the Galactic absorption in\nthat direction (~10^22 cm^-2), suggesting a probable nearby object.\nNote that there is not any X-ray source (flux upper limit of ~10^-15\nergs*cm^-2*s^-1) coincident with the position of the bright radio\nsource reported in GCN 4039 and GCN 4057 (van der Horst et al.).\n\nAt this stage, this source cannot be unambiguously identified neither\nas a Soft Gamma-Ray Repeater in quiescence, nor as the responsible\nfor the GRB 050925.\n\nWe thank the XMM-Newton team for having performed this observation.",
  "circularId": 4264,
  "createdOn": 1131736920000,
  "email": "N.Rea@sron.nl",
  "subject": "GRB/SGR 050925: XMM-Newton ToO observation",
  "submitter": "Nanda Rea at SRON  <N.Rea@sron.nl>"
}