Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 6569

GRB070621: Swift XRT refined analysis
2007-06-22T11:31:25Z (17 years ago)
Boris Sbarufatti at INAF-IASF-Pa <>
B. Sbarufatti (INAF-IASFPA), P. Romano, C. Guidorzi (Univ. Bicocca &  
A. Moretti (INAF-OAB) report, on behalf of the Swift-XRT team

We have analysed the first three orbits of Swift XRT data  for GRB070621
(Sbarufatti et al., GCN Circ. 6560), consisting of 150 s in Window  
mode data and 1.3 ks in Photon Counting mode.

The UVOT enhanced XRT position (Sbarufatti et al., GCN Circ. 6567) is
RA, Dec = 323.79225, -24.81752 which is equivalent to:

RA (J2000):   21 35 10.14
Dec (J2000): -24 49 03.1

with an uncertainty of 2.0 arcsec (90% confidence).

The X-ray light curve exhibits an initial steep decay (index -3.8  
up to T+380 s. A flare is observed around T+150s. After the break, the
count-rate decays with a power-law index of -0.91 +/- 0.04. If the  
slow decay continues, the predicted count rate 24h after the trigger is
2.1E-2 counts/s, corresponding to  a flux of 1.8E-12 ergs cm^-2 s^-1.

The WT and PC spectra can be fitted simultaneously with an absorbed
power-law model with a photon index 2.5+/-0.3 and a column density
(4.4 +/- 0.9)E21 cm^-2, significantly in excess with respect to the
galactic value (3.5E20 cm^-2, Dickey & Lockman, 1990). The absorbed
(unabsorbed) fluxes are 8.4E-10 (2.2E-09) ergs cm^-2 s^-1 for
the WT spectrum and 1.4E-11 (3.6E-11) ergs cm^-2 s^-1  for
the PC spectrum.

This circular is an official product of the XRT team.
Looking for U.S. government information and services? Visit