[vsnet-grb-info 8828] GRB 100115A: Swift-XRT candidate afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10326
SUBJECT: GRB 100115A: Swift-XRT candidate afterglow
DATE:    10/01/16 10:59:04 GMT
FROM:    Raffaella Margutti at U. di Milano Bicocca  <raffaella.margutti at brera.inaf.it>

R. Margutti (INAF-OAB), B. Sbarufatti (OAB), J. R. Cummings 
(NASA/GSFC/UMBC),
M. De Pasquale (MSSL/UCL) report on behalf of the Swift-XRT team:

Swift began observing the field of the Swift BAT Slew Survey (BATSS)
GRB 100115A (Cummings et al. GCN Circ. 10325) 40ks  after the trigger.
Using 2.5 ks of XRT Photon Counting mode data we detect a single
X-ray source source inside the BAT error circle at
RA, DEC= 3.3664, -0.8263 which is equivalent to:

RA (J2000): 00h 13m 27.93s
Dec (J2000): -00d  49' 34.8"

with an uncertainty of 6.8 arcsec (radius, 90% confidence).

The source is detected at a level of 6.6x10^-3 count sec^-1.
Given the current statistics it is not possible to determine whether
this source is fading.

A tentative spectrum formed from the PC mode data can be fitted with
an absorbed power-law with a photon spectral index of 2.7 (+1.7, -0.8). The
best-fitting absorption column is  consistent with the Galactic value
of 3.1 x 10^20 cm-2 (Kalberla et al. 2005). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 2.9 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020126.

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