Re: ACIS-S3: a spurious period of exact 1000 seconds

From: Samar Safi-Harb (samar@Physics.UManitoba.CA)
Date: Tue Jul 09 2002 - 15:46:37 EDT


Hi

Yes, I ran into a similar very nice period before..
It's probably dithering... Check the hidden
parameter in the aspect file *asol1*
(plot RA vs time for example)

Samar

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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