TITLE:   GCN CIRCULAR
NUMBER:  9463
SUBJECT: GRB 090531B: Swift-XRT candidate afterglow position
DATE:    09/05/31 20:27:50 GMT
FROM:    Boris Sbarufatti at INAF-IASF-Pa  <sbarufatti@ifc.inaf.it>

B. Sbarufatti, V. Mangano (INAF-IASFPA) and
J. R. Cummings (NASA/UMBC) report on behalf of the
Swift-XRT team


The XRT began observing the field of GRB 090531B
(trigger 353728, Cummins,  et al., GCN Circ 9461) at
19:26:22 UT, 3026 seconds after the BAT trigger, as
soon as the burst went outside the Earth limb observing
constraint.
Using promptly downlinked data we find an X-ray
source with an enhanced position: RA,Dec = 252.0748, -36.0350
(degrees) which is equivalent to:

RA  (J2000.0) = 16 48 17.95
DEC (J2000.0) = -36 02 06.0

with an uncertainty of 3.4 arcsec (radius, 90% containment).
This location is 47.8 arcseconds from the BAT onboard position, inside  
the BAT
error circle.

This circular is an official product of the Swift-XRT team.

[GCN OPS NOTE(03sep09): Per operator's desire, the Subject line
was corrected from "090831B" to "090531B". F.Marshall and H.Krimm noticed this.]