{
  "bibcode": "2004GCN..2656....1C",
  "body": "S. Campana and A. Moretti (INAF-Osservatorio astronomico di Brera) report on\nbehalf of a larger team:  \n\n\"We analyzed the second Chandra ACIS-S observation of the XRF040812 \n(Gotz et\nal. 2004, GCN 2640). We carried out spectral analysis of our previous\nafterglow candidate (CXOJ162602.3-444349, Campana & Moretti GCN 2649, \nsee also\nPatel et al. GCN 2648, 2655). The source is still very hard with a power law\nphoton index of 0.9+/-0.6 (fixing the column density to the Galactic \nvalue of\n5.3x10^21 cm-2 and using Cash statistics in the XSPEC fit). The spectrum is\nslightly softer than in the first observation (Campana & Moretti GCN\n2649). The unabsorbed 0.5-10 keV source flux is 9.30x10^-14 erg cm-2 s-1 a\nfactor of ~3 lower than in the previous Chandra observation. A constant\ntemporal evolution is not consistent with the data at a ~4.5 sigma level. A\npower law decay describes better the temporal evolution with a time decay as\nt^-1.4(+/-0.6) (90% confidence level, note that this is different from the\nPatel et al. GCN 2655, since we fitted the flux evolution and not the counts\nevolution).\"\n\nThis message can be cited.",
  "circularId": 2656,
  "createdOn": 1093424030000,
  "email": "campana@merate.mi.astro.it",
  "subject": "XRF040812: possible afterglow second Chandra observation",
  "submitter": "Sergio Campana at INAF-OAB  <campana@merate.mi.astro.it>"
}