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 4992

GRB 060421: Swift-XRT refined analysis
2006-04-21T15:32:18Z (18 years ago)
Kim Page at U.of Leicester <>
M.R. Goad, K.L. Page (U Leicester) and D.N. Burrows (PSU) report on 
behalf of the Swift-XRT team:

We have analysed the first 14 ks of Photon Counting (PC) mode data,
starting 97 seconds after the BAT trigger time, determining a refined
position of

RA (J2000):   22 54 32.63
Dec(J2000):  +62 43 50.07
with an estimated uncertainty of 3.8 arcsec (90% containment). This is 1.7 
arcsec from the initial XRT position given by Goad & Page in GCN 4987 and 
16.2 arcsec from the on-board BAT position quoted in GCN 4985 (Goad et 

The X-ray source was initially quite faint, with a peak count rate of only
~1 count s^-1. The light-curve shows a flat decay of alpha = 0.49 +/-
0.29, breaking to a steeper slope of alpha = 1.54 +/- 0.36, approximately
1500 seconds after the burst.

Because of the faintness of the afterglow, only 3 seconds of data were
obtained in Windowed Timing mode before switching into PC. The first orbit
of PC data (97-717 seconds post-trigger) can be modelled with a simple
power-law of Gamma = 1.54 +/- 0.34, with the Galactic absorbing column of
1e22 cm^-2. The observed (unabsorbed) flux over 0.3-10 keV for this time
period is 3.78e-11 (5.64e-11) erg cm^-2 s^-1.

Assuming the current rate of decay continues, the estimated count rate at 
24 hours is 4.2e-3 count s^-1, corresponding to an observed (unabsorbed) 
flux of 4.55e-14 (6.38e-14) erg cm^-2 s^-1.

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