Up to top level
AO15   AO16   AO17   AO18   AO19   Backgrounds   Calibration   Conference   Data   Docs   EPICMOS   EPICpn   Feedback   Gallery   Misc   OM   Pending   PhD_Theses   Publications   RGS   RadMonitor   SAS_Hardware   SAS_WS   SASv16.0   SASv16.0_Installation   SASv16.1   SASv16.1_Installation   SASv17.0   SASv17.0_Installation   SASv18.0   SASv18.0_Installation   SciSim   Simulators_other   Suggestions   Trash   Visibility   XMM-bouncing   XMM-news   XRPS   XSA   esas   incoming  

Logged in as guest

Viewing OM/9811
Full headers

From: Adrian Turner <akt21@ast.cam.ac.uk>
Subject: om light curve
Compose reply
Download message
Move To:
2 replies: 1 2
0 followups:

Private message: yes  no

Notes:

Notification:


Date: Mon, 05 Jan 2004 12:00:59 +0000
From: Adrian Turner <akt21@ast.cam.ac.uk>
To: xmmhelp <xmmhelp@xmm.vilspa.esa.es>
Subject: om light curve
Dear Helpdesk,

I've produced a light curve with the om by doing aperture photometry on 
a number of sequential frames. In the image is an active galaxy, where 
the central nucleus and host galaxy are apparent, as are two field 
stars. One field star is relatively far away from the central nucleus 
and has a non-varying light curve as it should. The other is much closer 
to the central nucleus (~11 pixels centre to centre) and has a light 
curve that varys in the opposite sense to the active nuclues light 
curve. The light curve variations are of the order 10%. The light curve 
of the second field star should obviously not be (anti)correlated with 
the active nucleus light curve. Is there any effect in the detector that 
means the sensitivity of the surrounding pixels is affected by 
variations in a bright source that could explain this effect? If not can 
you think of any other cause of this?

Many Thanks

Adrian Turner


Reply 1

Resend
From: Matthias Ehle <xmmhelp@xmm.vilspa.esa.es>
To: akt21@ast.cam.ac.uk
Subject: Re: om light curve (PR#9811)
Date: Mon Jan  5 12:38:46 2004
Dear Adrian Turner,

  I have forwarded your helpdesk question to the OM experts and will
let you have their reply as soon as possible. 

Cheers,
  Matthias.

Matthias Ehle 
XMM-Newton SOC 
User Support Group


Reply 2

Resend
From: Matthias Ehle <xmmhelp@xmm.vilspa.esa.es>
To: akt21@ast.cam.ac.uk
Subject: Re: om light curve (PR#9811)
Date: Wed Jan  7 11:41:20 2004
Dear Adrian Turner,

please find attached below now the reply from the OM experts.

Cheers,
  Matthias

---

We do not see that the sensitivity of the surrounding pixels is
affected by variations in a bright source. A relevant example is
that we have observed AB Dor field with different position angles
(This field has a very bright straylight feature in the boresight and
a strong out-of-focus smoke ring image). The field star photometry
is better than 3%.

For your data, straylight might be important, and also the bright central
nucleus can affect the background extraction of the second field star.
You can try to do photometry using several different aperture radii and use
several ways to measure the background, than you might figure out
the problem. 

Up to top level
AO15   AO16   AO17   AO18   AO19   Backgrounds   Calibration   Conference   Data   Docs   EPICMOS   EPICpn   Feedback   Gallery   Misc   OM   Pending   PhD_Theses   Publications   RGS   RadMonitor   SAS_Hardware   SAS_WS   SASv16.0   SASv16.0_Installation   SASv16.1   SASv16.1_Installation   SASv17.0   SASv17.0_Installation   SASv18.0   SASv18.0_Installation   SciSim   Simulators_other   Suggestions   Trash   Visibility   XMM-bouncing   XMM-news   XRPS   XSA   esas   incoming  

Logged in as guest


Please make your (short) question the subject of your request!


Web interface using JitterBug ... back to the XMM home page