TITLE:   GCN CIRCULAR
NUMBER:  12994
SUBJECT: GRB 120226A: Fermi-LAT data analysis
DATE:    12/02/28 19:12:33 GMT
FROM:    Weikang Zheng at U.of Michigan  <zwk@umich.edu>

Weikang Zheng and Carl Akerlof report on behalf of the ROTSE
collaboration:

We analyzed the high energy LAT data of GRB 120226A (Vasileiou and
Racusin, GCN 12989) using the matched filter technique (Akerlof et al,
2010, ApJ, 725, L15; 2011 ApJ, 726, 22; Zheng et al. 2012, ApJ 745,72,
GCN 12822). We only selected the photons with energy above 100 MeV in
our pipeline analysis. Our localization result gives the coordinate of
Ra = 300.05, Dec=48.81 (J2000) with uncertainty ~0.5 degree. This
location is about 7 degrees away from GBM trigger (Ra = 304.29,Dec =
42.1) and about 9 degrees away from the LAT location (Ra = 305.30, Dec =
40.75) given in GCN 12989. Our localization is much closer to the center
of IPN location (Ra = 302.930, Dec = 48.665, K. Hurley et al. GCN
12993), about 2 degrees away.

The LAT data signal is weak, too low to claim a firm detection. Only
four photons were identified near the estimated coordinate within a 50s
time window following the GBM trigger but by extending the duration to
250s, the number of photons increases to about 10. We encourage X-ray
follow-up observations of the new location.

All the pipeline results including the skymap can be found at the
following link:
http://www.rotse.net/LAT/GBMTriggers/351982459/351982459_res.html