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From: bianchi@fis.uniroma3.it
Subject: pn lightcurve drops to zero count
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2 followups: 1 2

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Date: Wed, 9 Jul 2003 13:24:42 GMT
From: bianchi@fis.uniroma3.it
To: xmmhelp@xmm.vilspa.esa.es
CC: bianchi@fis.uniroma3.it
Subject: pn lightcurve drops to zero count
Full_Name: Stefano Bianchi
Submission from: (NULL) (193.204.162.2)


I've extracted a pn lightcurve from a pn event file generated by epproc (SAS
5.4.1). I've noticed a sudden dip in the lightcurve, with bins that drop to zero
counts.
Is this a known issue?
I can send you the lightcurve file.

Thanks,

Stefano


Reply 1

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From: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
To: bianchi@fis.uniroma3.it
Subject: Re: pn lightcurve drops to zero count (PR#8793)
Date: Wed Jul  9 14:37:11 2003
Dear Stefano,

the two main reasons for such a behavior are:
 - drop of the telemetry
 - the the camera was going into counting mode

Form time to time some telemetry is lost, which
means that you have no photons in the observation.
Therefore, please, check if you pointing contains
photons at all during the drop in the light curve.

If your source is very bright, then the camera was
switching into the counting mode, as the processors
was not able to handle the amount of data. This can
also happen during a flare in the background. Do you
see indication that the source and/or the background
was increasing just before the drop in the lightcurve?

With best regards
Norbert


Followup 1

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Date: Wed, 09 Jul 2003 16:56:10 +0200
From: Stefano Bianchi <bianchi@fis.uniroma3.it>
To: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
Subject: Re: pn lightcurve drops to zero count (PR#8793)
Dear Norbert,
thanks for your prompt reply!
The observation is severely affected by high background. The cleaning 
removed something like half of the exposure time.
I also extracted the lightcurve on the cleaned avent file, but still 
have this sudden drop to zero.
Is it normal?

Thanks, Stefano

Norbert Schartel wrote:
> Dear Stefano,
> 
> the two main reasons for such a behavior are:
>  - drop of the telemetry
>  - the the camera was going into counting mode
> 
> Form time to time some telemetry is lost, which
> means that you have no photons in the observation.
> Therefore, please, check if you pointing contains
> photons at all during the drop in the light curve.
> 
> If your source is very bright, then the camera was
> switching into the counting mode, as the processors
> was not able to handle the amount of data. This can
> also happen during a flare in the background. Do you
> see indication that the source and/or the background
> was increasing just before the drop in the lightcurve?
> 
> With best regards
> Norbert
> 
> 
> 




Reply 2

Resend
From: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
To: bianchi@fis.uniroma3.it
Subject: Re: pn lightcurve drops to zero count (PR#8793)
Date: Wed Jul  9 15:32:05 2003
Dear Stefano,

can I call you?

if yes, can you give me your phone number?

With best regards
Norbert


Followup 2

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Date: Wed, 09 Jul 2003 17:34:24 +0200
From: Stefano Bianchi <bianchi@fis.uniroma3.it>
To: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
Subject: Re: pn lightcurve drops to zero count (PR#8793)
Oh yes!
The number is

+39-06-55177299

Thanks,

Stefano

Norbert Schartel wrote:
> Dear Stefano,
> 
> can I call you?
> 
> if yes, can you give me your phone number?
> 
> With best regards
> Norbert
> 
> 
> 



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