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From: waynewengjianbin@outlook.com
Subject: fitted flux difference between XMM and Chandra
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Date: Wed, 18 Sep 2019 17:31:48 +0200
From: waynewengjianbin@outlook.com
To: xmmhelp@sciops.esa.int
Subject: fitted flux difference between XMM and Chandra
Full_Name: Jianbin Weng
Submission from: (NULL) (193.147.152.102)


Dear Helpdesk staff,

Hi! Recently I'm working on SNR G306.3-0.9 and preforming a simultaneous
analysis on XMM-Newton and Chandra observation. The XMM-Newton observation ID is
0691550101, performed in 2013, and SAS version is 18.0.0.

I use task epchain/emchain to reprocess the data, and evselect to extract the
source and background spectra. The XMM and Chandra spectra(0.3-8.0 keV) are both
fitted in Xspec, but the fitted flux(0.3-8.0 keV) of XMM spectra is ~ 5.8e-12
erg cm-2 while that of Chandra is 6.4e-12 erg cm-2, about 10% higher. The flare
and piled up effect were examined roughly, but they didn't seemed to be the
problem. I also checked the influence of CCD gap. I extracted small regions
within the SNR. The small regions which are crossed by CCD gap, have 20% lower
flux ,while those which don't have a gap passing through still show 10% lower
flux.

(In case that you need more information, the Chandra observation is 13419,14812.
The model for spectral fitting is tbabs*(apec+vnei))

May I ask whether there was anything I missed that would cause a lower fitted
flux or what tasks that usually go wrong I should recheck? Could it be some
systematic differences of XMM and Chandra spectral fitted flux, the problem of
cross-calibration? Looking forward to your reply. Many thanks!

All my best,
Jianbin Weng
Nanjing University


Reply 1

Resend
From: Simone Migliari <xmmhelp@sciops.esa.int>
To: waynewengjianbin@outlook.com
Subject: Re: fitted flux difference between XMM and Chandra (PR#2%2%2%2)
Date: Mon Sep 23 15:40:59 2019
Dear Jianbin Wen

apologies for the late reply. We are working with the calibration team and will
get back to you as 
soon as possible.

Thank you for your patience
Kind regards
Simone


> Full_Name: Jianbin Weng
> Submission from: (NULL) (193.147.152.102)
> 
> 
> Dear Helpdesk staff,
> 
> Hi! Recently I'm working on SNR G306.3-0.9 and preforming a simultaneous
> analysis on XMM-Newton and Chandra observation. The XMM-Newton observation
ID
is
> 0691550101, performed in 2013, and SAS version is 18.0.0.
> 
> I use task epchain/emchain to reprocess the data, and evselect to extract
the
> source and background spectra. The XMM and Chandra spectra(0.3-8.0 keV) are
both
> fitted in Xspec, but the fitted flux(0.3-8.0 keV) of XMM spectra is ~
5.8e-12
> erg cm-2 while that of Chandra is 6.4e-12 erg cm-2, about 10% higher. The
flare
> and piled up effect were examined roughly, but they didn't seemed to be
the
> problem. I also checked the influence of CCD gap. I extracted small
regions
> within the SNR. The small regions which are crossed by CCD gap, have 20%
lower
> flux ,while those which don't have a gap passing through still show 10%
lower
> flux.
> 
> (In case that you need more information, the Chandra observation is
13419,14812.
> The model for spectral fitting is tbabs*(apec+vnei))
> 
> May I ask whether there was anything I missed that would cause a lower
fitted
> flux or what tasks that usually go wrong I should recheck? Could it be
some
> systematic differences of XMM and Chandra spectral fitted flux, the problem
of
> cross-calibration? Looking forward to your reply. Many thanks!
> 
> All my best,
> Jianbin Weng
> Nanjing University
> 
> 


Reply 2

Resend
From: Simone Migliari <xmmhelp@sciops.esa.int>
To: waynewengjianbin@outlook.com
Subject: Re: fitted flux difference between XMM and Chandra (PR#2%2%2%2)
Date: Thu Sep 26 10:20:48 2019
Dear Jianbin Weng

thank you for your patience. Indeed, the difference that you observe, ~10%
depending on which 
instruments you are comparing, could be explained by known cross-calibration
issues. 
Please check the following cross-mission calibration papers as reference. 

K.Madsen, et al., IACHEC Cross-calibration of Chandra, NuSTAR, Swift, Suzaku,
XMM-Newton with 
3C 273 and PKS 2155-304
2017, The Astronomical Journal, 153, 2

P.Plucinsky, et al., SNR 1E 0102.2-7219 as an X-ray calibration standard in the
0.5-1.0 keV bandpass 
and its application to the CCD instruments aboard
Chandra, Suzaku, Swift and XMM-Newton
2017, Astronomy & Astrophysics, 597, 31

I hope this helps.
Kind regards
Simone



> Full_Name: Jianbin Weng
> Submission from: (NULL) (193.147.152.102)
> 
> 
> Dear Helpdesk staff,
> 
> Hi! Recently I'm working on SNR G306.3-0.9 and preforming a simultaneous
> analysis on XMM-Newton and Chandra observation. The XMM-Newton observation
ID
is
> 0691550101, performed in 2013, and SAS version is 18.0.0.
> 
> I use task epchain/emchain to reprocess the data, and evselect to extract
the
> source and background spectra. The XMM and Chandra spectra(0.3-8.0 keV) are
both
> fitted in Xspec, but the fitted flux(0.3-8.0 keV) of XMM spectra is ~
5.8e-12
> erg cm-2 while that of Chandra is 6.4e-12 erg cm-2, about 10% higher. The
flare
> and piled up effect were examined roughly, but they didn't seemed to be
the
> problem. I also checked the influence of CCD gap. I extracted small
regions
> within the SNR. The small regions which are crossed by CCD gap, have 20%
lower
> flux ,while those which don't have a gap passing through still show 10%
lower
> flux.
> 
> (In case that you need more information, the Chandra observation is
13419,14812.
> The model for spectral fitting is tbabs*(apec+vnei))
> 
> May I ask whether there was anything I missed that would cause a lower
fitted
> flux or what tasks that usually go wrong I should recheck? Could it be
some
> systematic differences of XMM and Chandra spectral fitted flux, the problem
of
> cross-calibration? Looking forward to your reply. Many thanks!
> 
> All my best,
> Jianbin Weng
> Nanjing University
> 
> 

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