[vsnet-grb-info 5871] GRB080325: XRT Refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7521
SUBJECT: GRB080325: XRT Refined Analysis
DATE:    08/03/25 23:24:28 GMT
FROM:    Loredana Vetere at PSU  <vetere at astro.psu.edu>

L. Vetere, J. L. Racusin (PSU) report on behalf of the Swift-XRT team:

We have analysed the first 8 orbits of Swift-XRT data obtained for BAT GRB
080325 (trigger 307604, Vetere et al., GCN Circ. 7512).

The data consist of 360 s in Windowed Timing (WT) mode, starting 160 s after the
BAT trigger and 7.8 ks in Photon Counting (PC) mode. The astrometrically
corrected X-ray position is given  in Osborne et al. GCN 7513.

The early WT light-curve shows flaring activity followed by a fast decay that
can be fit by a power law with a slope of alpha1=5.7 ± 0.5. The following PC
light curve starts at 3.6 ks after BAT trigger and shows a much slower decay
with a slope of alpha2=0.8 ± 0.2. If the light-curve continues to decay at the
same rate, we predict an XRT count rate of 0.011 count/s at T+24 hours.

The spectrum formed from all the WT data can be modeled with a power-law of
photon index Gamma = 2.4 ± 0.1, with an absorbing column of NH = (3.0 ± 0.1)e21
cm^-2, significantly in excess with respect to the Galactic value of 3.81e20
cm^-2.

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