[vsnet-grb-info 5891] GRB 080330: error in reported XRT position

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7541
SUBJECT: GRB 080330: error in reported XRT position
DATE:    08/03/30 04:36:19 GMT
FROM:    David Burrows at PSU/Swift  <dnburrows at gmail.com>

D. N. Burrows (PSU) reports on behalf of the Swift XRT team:

The XRT position for GRB 080330 that was distributed in GCN Circ. 
7537 was incorrect.   The initial on-board XRT position determined 
immediately after the spacecraft slew was

GRB_RA:          169.2707d {+11h 17m 04.9s} (J2000),
GRB_DEC:         +30.6223d {+30d 37' 20.2"} (J2000),

with a nominal error circle radius of 5.0 arcseconds.  This position 
was 6.1 arcseconds from the UVOT position.  It appears that shortly 
after arriving on-target, the spacecraft began slowly drifting 
because the star tracker did not lock properly on the star 
field.  The updated XRT position based on promptly downloaded data 
was determined using inaccurate aspect information from the satellite 
and was therefore incorrect.  We apologize for any confusion that 
this may have caused.  We reiterate that the XRT position appears to 
be consistent with the optical position.