GCN Circular 8321
Subject
AXP 1E1547.0-5408: Swift-XRT Team refined analysis
Date
2008-10-04T00:00:26Z (16 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
K.L. Page, A.P. Beardmore (U. Leicester) and H.A. Krimm (CRESST/GSFC/USRA)
report on behalf of the Swift-XRT team:
Swift-XRT started observing the field of the AXP 1E1547.0-5408 82 seconds
after the first BAT trigger (Krimm et al., GCN Circ. 8311) and a clear
X-ray source was found. Using 84 s of XRT Photon Counting mode data and 1
UVOT images, we find an astrometrically corrected X-ray position (using
the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1
catalogue) of RA, Dec = 237.72433, -54.30643 which is equivalent to:
RA (J2000): 15 50 53.84
Dec (J2000): -54 18 23.2
with an uncertainty of 1.4 arcsec (radius, 90% confidence). This position
is 2.5 arcsec from CXOU J155054.1-541824 (Gelfand & Gaensler 2007), which
they identify with 1E1547.0-5408.
The XRT detected an increased count rate at around 520 s, coincident with
one of the BAT spikes mentioned in Krimm et al. (GCN Circ. 8318);
similarly a brightening was seen at the time of the second trigger
reported in GCN Circ. 8312. In both cases, the XRT registered a single,
bright 2.5 s frame of data.
The spectrum from the first two orbits of PC data can be modelled by a
highly-absorbed power-law, with Gamma = 2.33 +0.31/-0.29 and NH = (4.9
+0.8/-0.7) x 10^22 cm^-2.
This circular is an official product of the Swift-XRT team.