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From: "Andersson, Karl E." <kanderss@SLAC.Stanford.EDU>
Subject: XMM data analysis problems
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Date: Thu, 06 Mar 2003 13:56:48 -0800
From: "Andersson, Karl E." <kanderss@SLAC.Stanford.EDU>
Subject: XMM data analysis problems
To: "'xmmhelp@xmm.vilspa.esa.es'" <xmmhelp@xmm.vilspa.esa.es>
Hi

I've analysed XMM/EPIC MOS and PN data from galaxy cluster ABELL 1689 in order
to measure the temperature gradient and finally to be able to say something
about the dark matter distribution.

First of all I wanted to find the temerature for the plasma from the whole
source region in the ABELL 1689 exposure.
Background extraction was made from both blank sky regions in the same exposure
and also from XMM data from the Lockman hole exposures. I discovered an excess
of soft x-rays (-> 1.5 keV) in the PN data compared to the MOS data. I was
wondering if this might be an instrumental effect.
MOS data fits a wabs(mekal) model with 9.2 keV and 0.26 abundance, this is also
a good fit to PN data above 1.5 keV. PN data has been cleaned from out-of-time
events. Also I found a strong peak at 8 keV in the background data from the
ABELL 1689 exposure around the cluster which gives me a dip in the net spectra
after subtracting the background spectra from the source. I can find no natural
source for this. Would you be able to answer some of these questions for me.
Thank you.

Best Regards,

Karl Andersson


Reply 1

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From: Michel G. Breitfellner <xmmhelp@xmm.vilspa.esa.es>
To: kanderss@SLAC.Stanford.EDU
Subject: Re: XMM data analysis problems (PR#8202)
Date: Fri Mar  7 14:28:42 2003
Dear Dr. Andersson,

Your questions were forwarded to our specialist and we will
come back to you as soon as possible.

With best regards,
Michel G. Breitfellner
XMM-Newton User Support Group


Reply 2

Resend
From: Michel G. Breitfellner <xmmhelp@xmm.vilspa.esa.es>
To: kanderss@SLAC.Stanford.EDU
Subject: Re: XMM data analysis problems (PR#8202)
Date: Fri Mar  7 18:11:22 2003
Dear Dr. Andersson,

Please, find enclosed the answer from our instrument specialist:

The 8 keV feature is clearly related to the spatially inhomogeneous
Cu-K feature (see section 1.5 in the EPIC cal status doc available at
http://xmm.vilspa.esa.es/docs/documents/CAL-TN-0018-2-0.pdf )

The 1.5 keV feature is most probably not related to the Al, but could
be related to the old (wrong) QE if  the user is using old matrices.
You should fit the data with state of the art matrices of SAS 5.4.1 
and repeat the analysis, keeping in mind the spatial distribution of
the Cu-K in the camera.

With best regards,
Michel G. Breitfellner
XMM-Newton User Support Group


Followup 1

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Date: Fri, 07 Mar 2003 15:35:48 -0800
From: "Andersson, Karl E." <kanderss@SLAC.Stanford.EDU>
Subject: RE: XMM data analysis problems (PR#8202)
To: "'Michel G. Breitfellner'" <xmmhelp@xmm.vilspa.esa.es>
The arf and rmf matrices used were generated with:

rmfgen format=var rmfset=resp$ID.rmf spectrumset=spectrum$ID.pha
threshold=1.0e-6

arfgen spectrumset=spectrum$ID.pha arfset=arf$ID.arf withrmfset=true
rmfset=resp$ID.rmf withbadpixcorr=true badpixlocation=$1 extendedsource=false
modelee=true withsourcepos=false useodfatt=false

The CCF-files used are all from February 4 or February 26. The SAS version is
5.4.1.

Does any of this explain the 1.5 keV problem?
Thanks,

Karl Andersson

-----Original Message-----
From: Michel G. Breitfellner [mailto:xmmhelp@xmm.vilspa.esa.es] 
Sent: Friday, March 07, 2003 10:11 AM
To: Andersson, Karl E.
Subject: Re: XMM data analysis problems (PR#8202)

Dear Dr. Andersson,

Please, find enclosed the answer from our instrument specialist:

The 8 keV feature is clearly related to the spatially inhomogeneous
Cu-K feature (see section 1.5 in the EPIC cal status doc available at
http://xmm.vilspa.esa.es/docs/documents/CAL-TN-0018-2-0.pdf )

The 1.5 keV feature is most probably not related to the Al, but could
be related to the old (wrong) QE if  the user is using old matrices.
You should fit the data with state of the art matrices of SAS 5.4.1 
and repeat the analysis, keeping in mind the spatial distribution of
the Cu-K in the camera.

With best regards,
Michel G. Breitfellner
XMM-Newton User Support Group



Reply 3

Resend
From: Michel G. Breitfellner <xmmhelp@xmm.vilspa.esa.es>
To: kanderss@SLAC.Stanford.EDU
Subject: Re: XMM data analysis problems (PR#8202)
Date: Fri Apr 11 14:41:57 2003
Dear Dr. Andersson,

Please find enclosed the answer from our instrument specialist:

the Abell (0374_0093030101_PNS003) observation was performed in eFF thin,
while the Lockman Hole was performed in "FF Thin1".
It can not be recommend to use the BG region from a different mode for BG
subtraction.
In addition the instrument set up before rev 220 used a different offset
calculation, therefore it is not possible to use those to observations in
a 1:1 BG subtraction.

Concerning the Al Feature: Since the Al Fluorescence line is homogeneous
over the CCD you get for selections of off-axis regions relative more Al
as on-axis. This could cause a deficit in your final analysis. A stronger
deficit in the MOS case could thus cause your difference between MOS and pn.
So we think, that your Al feature is also instrument related.

With best regards,
Michel G. Breitfellner
XMM-Newton User Support Group

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