TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1049
SUBJECT: SGR 1900+14: Detection of extended X-ray emission
DATE:    01/04/26 00:05:20 GMT
FROM:    Derek Fox at CIT  <derekfox@astro.caltech.edu>

D. W. Fox and D. L. Kaplan (Caltech) report:  

"Analysis of data from the 22 April 2001 Chandra observation (GCN
1046, 1047), barycenter-corrected with the preliminary CXC ephemeris,
reveals that the source emission is pulsed at a period of P =
5.17288(5) s with a pulse strength of 14.3(2)% RMS that remains
constant (within errors) throughout the observation.  Separation of
the source photons into "on-pulse" and "off-pulse" components of 1/3
cycle each reveals that the off-pulse spatial distribution is
significantly broader than the on-pulse distribution.  Since the
observation is taken in continuous-clocking mode, we can only make
this determination in one dimension.  Nonetheless, the sigma-widths of
the one-dimensional Gaussian PSFs are 0.98(1) arcsec for on-pulse
photons and 1.08(2) arcsec for off-pulse photons, different at
>5-sigma level.  We attribute this difference in widths to the
presence of an underlying X-ray nebula."