[vsnet-grb-info 1778] GRB 050714B: refined XRT analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3618
SUBJECT: GRB 050714B: refined XRT analysis 
DATE:    05/07/15 11:26:34 GMT
FROM:    Andrew Levan at U.of Leicester  <anl at star.le.ac.uk>

K. Page, A. Beardmore, A. Levan, E. Rol, J.P. Osborne (U. Leicester),
D. Morris, D. Burrows (PSU), A. Smale (NASA HQ), L. Cominsky (Sonoma
State U.) and N. Gehrels (GSFC)  report for the Swift XRT team:

We have analysed the XRT data for GRB 050714B taken 157-18700
seconds after the trigger. PSF fitting of the candidate afterglow in the
photon counting (PC) mode observations yields a refined position of

RA: 11h 18m 48.0s (J2000)
Dec:-15d 32m 49.9s (J2000)

with an uncertainty of 6 arcseconds (90%). This position is offset
approximately 5.5 arcseconds from the position reported in GCN 3613
and does not contain object "A" found by Covino et al (GCN 3616).

XRT observations began in Windowed Timing (WT) mode 157 seconds after the
trigger and show a steep decline with a power-law decay index between 5
and 6, lasting for approximately 300 seconds. This is followed by a rise,
which peaks 400 seconds after the trigger and was recorded in PC
mode. No observations were performed between 546 and 5000 seconds. In
the interval 5000-18700 seconds a shallower decay of approximately 0.7
was seen. The behaviour is similar to that which has been seen in many
Swift afterglows and indicates that this transient is, most likely, a
GRB.

The spectrum of the early afterglow is exceptionally soft, having a photon
index of ~ 6, with evidence of spectral evolution between the WT and PC
mode observations. The mean unabsorbed fluxes in WT mode (157-220 seconds)
and PC mode (221-546 seconds) are 3.4e-9 and 1.7e-9 ergs/s/cm^2
respectively, in the 0.5-10 keV range. We note, however, that no
flux was detected above 2 keV by the XRT.