2S 1553-54: Swift/XRT position
P. T Boyd (NASA's GSFC), M. Still (UCL-MSSL), J. Kennea (Penn State) and H. A. Krimm (CRESST/GSFC/USRA)
The transient accreting pulsar 2S 1553-54, discovered in outburst by Swift/BAT on 2007 Dec 31 (Krimm, ATel #1345) was observed by Swift XRT for 4081 seconds on 2008 January 24 to determine a refined position. The pulsar, which is still detected by BAT at a level of about 35 mCrab, is a bright, marginally piled-up XRT source with position:

RA (J2000) 15 57 47.75 Dec (J2000) -54 24 52.4

with a 3.5 arc-second error (90% containment). The XRT error circle lies within the SAS-3 35 arc-second aperture (Apparao, 1978, Nature, 271, 225.

No optical counterpart is detected in any UVOT filter down to the following 3-sigma limiting magnitudes.

Filter	limiting Mag	exposure time (s) uvw2	19.8 	460 uvm2	19.5 	342 uvw1	19.3	230 u	19.0	115 b	19.4	115 v	18.4	115

This is the first detected outburst of this system since 1975 (SAS-3).
optical,x-ray,binary,pulsar,transient