{
  "bibcode": "2001GCN..1047....1F",
  "body": "D. W. Fox and D. L. Kaplan (Caltech) report on behalf of a larger\ncollaboration\"\n\n\"In response to the 18 April 2001 flare of SGR 1900+14 (GCN 1041) the\nChandra X-ray Observatory has undertaken a sequence of two public\n20-ksec observations of this source, on 22 and 30 April 2001.\n\nThe first observation began at 04:58 UT on 22 April and was taken in\ncontinuous-clocking mode (see also GCN 1046).  Examination of the\nlight curve reveals that at least one burst was observed, 9081 s after\nthe start of the observation.  Assuming the best-fit spectral\nparameters for the observation (see below), the peak 1-s flux of this\nburst was of order 5e-10 erg cm^-2 s^-1 (0.5-10 keV).\n\nSpectral fits to the full background-subtracted data set allow for at\nleast two emission models.  A power-law plus absorption model has\nbest-fit parameters of N_H = 3.18(2)e22 cm^-2, photon index alpha =\n2.70(1), and unabsorbed 0.5-10 keV flux of 4.20(4)e-11 erg cm^-2 s^-1.\nA power-law plus blackbody and absorption model has best-fit\nparameters of N_H = 2.56(2)e22 cm^-2, photon index alpha = 1.88(1),\nblackbody temperature kT = 0.532(3) keV, unabsorbed 0.5-10 keV flux of\n2.17(3)e-11 erg cm^-2 s^-1, and flux fraction for the blackbody\ncomponent of 29% (0.5-10 keV).  The addition of the blackbody\ncomponent is not supported by an F-test (65% confidence level) but is\nconsistent with models in the literature (Perna et al. 2001,\nastro-ph/0103273).  Analysis of the RXTE PCA data may help to clarify\nthe presence or absence of the blackbody component, as the PCA count\nrates inferred from the two models given above differ by 50%.\n\nNo narrow spectral features are apparent.  The two-sigma upper limit\nto the flux of a persistent 0.2-keV FWHM emission line in the 5-7 keV\nrange is 1e-5 photons cm^-2 s^-1.\n\nThis message may be cited.\"",
  "circularId": 1047,
  "createdOn": 988083484000,
  "email": "dfrail@nrao.edu",
  "subject": "SGR 1900+14, Chandra observations",
  "submitter": "Dale A. Frail at NRAO  <dfrail@nrao.edu>"
}