TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4600
SUBJECT: Refined XRT Position for GRB 060123
DATE:    06/01/25 20:30:16 GMT
FROM:    Josh Bloom at UC Berkeley  <jbloom@astron.berkeley.edu>

N. Butler and J. S. Bloom (UC Berkeley):

We determine a refined XRT positions for GRB060123 (Palmer et al.,  
GCN 4584)
by matching the positions of X-ray sources to positions of SDSS  
sources.  A
similar procedure was employed in GCN 4500 to refine the XRT position  
for
GRB060108.  Using 4 X-ray sources detected in 4.5 ksec of PC mode data
and 6 SDSS sources, we determine a frame offset for the XRT of:

Frame Offset: RA  -2.28 ; Dec 2.0 , 90% Conf. Error:  2.7"

Our refined XRT position for GRB060123 is then:

RA  11h 58m 47.66s       ;      DEC +45d 30' 50.55"
                                                         +/-  
3.1" (90% Conf.)

This refined XRT position is coincident with the SDSS galaxy noted in  
Bloom et al. (GCN 4595).  Given this, we suggest that this  
coincidence appears to disfavor the high-redshift hypothesis for the  
burst (Palmer et al., GCN 4584)."

The X-ray/optical source offsets are shown at:
     http://astro.berkeley.edu/~nat/060123/crosscor_sdss.jpg

The XRT overlap atop the SDSS and PAIRITEL images is:
     http://astro.berkeley.edu/~jbloom/grb060123-nat.ps.gz

We thank Dave Burrows at PSU for his assistance.