[AAVSO-HEN] XRF in NGC 2770: Search for X-ray periodicity

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  7172
SUBJECT: XRF in NGC 2770: Search for X-ray periodicity
DATE:    08/01/11 22:21:43 GMT
FROM:    Eran Ofek at Tel Aviv U.  <eran at wise1.tau.ac.il>

E. O. Ofek, S. R. Kulkarni, M. M. Kasliwal, A. Rau, S. B. Cenko (Caltech),
D. B. Fox (Penn State) on behalf of a larger collaboration.

We inspected the Swift X-ray observations of the X-ray transient
associated with NGC 2770 (Berger & Soderberg 2008; ATel 1353; GCN 7159).
We looked for periodicity in the X-ray data that may hint
on association with a fast rotating object.
We do not identify any (non-instrumental) periodicity in the
data, below the sampling frequency of 0.4 Hz.
We estimate that the fraction of photons that are modulated
periodically (if at all) is smaller than 10%.

The X-ray event started approximately at the beginning
of the XRT observation at UTC 2008 Jan 09.5652. Peak flux (in 10 s
intervals) was achieved about 65 s later.

We note that the analysis is based on 697 photons, within 20 pixels from the
transient location and detected within 1000 s of the
beginning of the XRT observation.