Hi Lui,
Is the source near the edge of a CCD? If so, you might be seeing the
dither period, which may be around 1ks.
Cheers,
Eric
------------------------------/>/</>/</--------------------------------
Eric Gotthelf
Columbia Astrophysics Laboratory WORK: 212-854-9047
Pupin Hall, Columbia University FAX: 212-854-8121
550 West 120th St, EMAIL: eric@astro.columbia.edu
New York, NY 10027, USA WEB: www.astro.columbia.edu/~eric
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On Tue, 9 Jul 2002, Jifeng Liu wrote:
> Dear Colleagues,
> i am examining a ACIS-S3 50ksec exposure, and find a period of exact 1000
> seconds. I use wavdetect to get all source regions with default ellipsigma
> setting, then i pick out some bright sources with Nphoton > 2000, and use
> XRONOS to carry out timing analysis, and find that a source with 43000+ x-ray
> photons shows a period of exactly 1000 seconds, the folded light curve shows a
> sine curve, and varying amplitude is about 20%. the other bright sources, and
> the background events do not show such periods. This period is so EXACTly
> 1000.00 seconds, that i cannot help thinking it's some kind of artifacts.
> Have any of you met such problems before?
>
> cheers,
> --
> jifeng
>
>
>
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