TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  155
SUBJECT: GRB980425: X-ray revised positions
DATE:    98/10/20 21:26:03 GMT
FROM:    SAX Science Operations at IAS/CNR Frascati  <saxsci@ias.rm.cnr.it>

GRB980425: revised SAX-NFI positions

L. Piro, IAS/CNR, Rome, Italy, R.C. Butler, ASI, Rome, Italy, F. Fiore, A.
Antonelli, BeppoSAX SDC, Roma, E. Pian, ITesre, Bologna, Italy, report: 

The majority of BeppoSAX observations were performed with the star tracker
Z (i.e., the one co-aligned with the NFI) in the attitude control loop.
However, a few observations could not be performed in this configuration,
but had to be carried out with the X and Y star trackers only.  We have
found out that, in these very infrequent cases, the attitude
reconstruction could have an error of up to 3'.  This problem does not
affect observations accomplished after May 5, 1998.  Prior to this date,
the only GRB which was observed by the NFI in this configuration is
GB980425.  The revised coordinates (equinox 2000.0) of the two sources
found in the WFC error box (Pian et al., GCN 61) are:
1SAXJ1935.0-5248, RA = 19h35m05.9s, Dec =-52o50'03";  
1SAXJ1935.3-5252, RA = 19h35m22.9s, Dec =-52o53'49",
with a conservative error radius of 1.5'.  Both updated positions are
still within the WFC error box (Soffitta et al., IAU Circ. No. 6884). 
However, 1SAXJ1935.0-5248 is at 50" from SN1998bw (Galama et al. 1998,
Nature, in press, astro-ph/9806175;  Kulkarni et al., Nature, in press,
astro-ph/9807001) and therefore consistent with it, while the variable
source 1SAXJ1935.3-5252 is 3' away, i.e., inconsistent.