GCN Circular 10535
Subject
Possible pulsation period in SGR 1833-0832
Date
2010-03-20T16:31:28Z (14 years ago)
From
Paolo Esposito at INAF-IASF,Milano <paoloesp@iasf-milano.inaf.it>
Paolo Esposito, Gian Luca Israel, Luigi Stella, Nanda Rea, Andrea Tiengo
report:
We analysed 22.5 ks of XRT data in Photon Counting (PC) mode of the new
soft gamma-ray repeater candidate SGR 1833-0832 (Gelbord et al. GCN Circ.
10526, 10531). The data were barycentered using the X-ray position
reported in Evans et al. (GCN Circ. 10530). We detect strong pulsations
from the X-ray source in the 2-10 keV band at 7.5653(5) sec. The
background subtracted pulsed fraction, defined as the semiamplitude of
sinusoidal modulation divided by the mean source count rate, is 64+/-4%.
The pulse is highly significant (the probability of such a signal to
appear by chance in the search, taking into account the 32768 trials, is
about 5E-18) and is not present in the background data. We caution however
that this value is close to three times the XRT PC frame time, 2.507 s. At
the link below a plot of the source and background data folded at our best
fit period and at 3*2.507 s can be seen. Further observations are needed
to confirm this period.
http://www.iasf-milano.inaf.it/~paoloesp/sgr1833.html
[GCN OPS NOTE(20mar10): Per author's request the Subject (a result of a
copy-pase mistake) was changed to "Possible pulsation period in SGR 1833-0832".]