TITLE:   GCN CIRCULAR
NUMBER:  22686
SUBJECT: Correction to Swift-XRT light curve fit for GRB 180504A in GCN 22685
DATE:    18/05/05 08:20:13 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:

The fit results to the Swift-XRT light curve provided in GCN 22685 were
incomplete. The correct fit is as follows:

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha= 1.47 (+0.16, -0.17). At T+222 s the decay
steepens to an alpha of 2.81 (+0.20, -0.14) before breaking again at
T+1078 s to a final decay with index alpha=0.83 (+/- 0.13).

If the light curve continues to decay with a power-law decay index of 0.83
, the count rate at T+24 hours will be 2.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x 10^-13
(1.3 x 10^-13) erg cm^-2 s^-1.

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

[GCN OPS NOTE(05may18): Per author's request, the GRB name
was added to the Subject-line.]