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 14555

GRB 130502B: Swift-XRT refined Analysis
2013-05-04T13:30:51Z (11 years ago)
Andrea Melandri at INAF-OAB <>
A. Melandri (INAF-OAB) and S. Immler (NASA/CRESST/GSFC) report on  
behalf of the Swift-XRT team:

We have analysed  8.3 ks of XRT data for the Fermi/LAT-detected burst:  
GRB 130502B (Kocevski  et al. GCN Circ. 14532), from 55.1 ks to 101.8  
ks after the Fermi/LAT trigger.

The object dectected in the first 3.4 ks of XRT data (Melandri &  
Immler GCN Circ. 14540) is now clearly fading. The light curve can be  
modelled with  a power-law decay with a decay index of alpha=1.52  

A spectrum formed from the PC mode data can be fitted with an absorbed  
power-law with a photon spectral index of 1.89 (+/-0.20). The best- 
fitting absorption column is  1.73 (+0.78, -0.71) x 10^21 cm^-2, in  
addition to the Galactic value of 1.1 x 10^21 cm^-2 (Kalberla et al.  
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion  
factor deduced from this spectrum  is 4.3 x 10^-11 (6.3 x 10^-11) erg  
cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Galactic foreground:    1.1 x 10^21 cm^-2
Intrinsic column:         1.73 (+0.78, -0.71) x 10^20 cm^-2
Photon index:	         1.89 (+0.21, -0.20)

The results of the XRT-team automatic analysis are available at

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