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From: ai onikata <ai@phys.chuo-u.ac.jp>
Subject: About RGS
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Date: Mon, 04 Aug 2003 07:11:06 +0900
From: ai onikata <ai@phys.chuo-u.ac.jp>
Subject: About RGS
To: xmmhelp@xmm.vilspa.esa.es
Cc: tsuboi@phys.chuo-u.ac.jp
Hello XMM-help desk

I am now dealing with XMM data, which is
"0111120201 archived RHO OPH CORE 21:07:52 33387 Michael Watson
2002-06-14 Y 1.713". The aiming point is RA =16 27 26.00, Dec = -24 40
48.0 in J2000.


I am interested in the spectrum of a young star ROXs21, which coordinate
is RA =16 27 19.50 Dec = -24 41 40.1in J2000.
However, I found inconsitency between RGS data and PN data of the source.

Each count rate is
RGS2==>7.3277E-03
PN==>0.2808

I checked pimms (heasarc).
It predicted RGS2 is 1.758E-02 cps when PN is 0.28.
(Model parameters are ... keV=0.7,Value of nH=0.11e+22)

Why was my rgs2 data ten times lower?

Thank you very much,

            Ai Onikata



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From: Pedro M. Rodriguez Pascual <xmmhelp@xmm.vilspa.esa.es>
To: ai@phys.chuo-u.ac.jp
Subject: Re: About RGS (PR#16315)
Date: Mon Oct  4 14:40:08 2004
Dear Ai Onikata,

Please, note that PIMMS is a Multi-Mission simulator rather than a data
analyzer. Further the simulation capabilities are very limited; in practice,
PIMMS is an extremely valuable tool for observations planning but not much for
data analysis. 

With regard to the question on the low count rate in rgs, the lower effective
area of RGS, as compared to pn, results in a much lower count rate (a factor
10-15, depending on actual input spectrum).

The comparison between pimms estimates and actual measures depends on the
validity of the model assumed and the actual uncertainties in the measured count
rates for the source, which is supposed to be on-axis for every instrument. For
the particular source you are interested in, it is clear that the source is not
on-axis neither in pn nor in RGS. Further, background estimates for such a
crowded field may be a major issue (to be added to the uncertainty in the model
parameters) both in pn and rgs. Therefore, I should not very much concerned
about a factor 2 difference between the counts (~130?) measured in rgs2 and the
count rate estimated by PIMMS after pn measures.

Sincerely, 

Pedro


> Hello XMM-help desk
> 
> I am now dealing with XMM data, which is
> "0111120201 archived RHO OPH CORE 21:07:52 33387 Michael Watson
> 2002-06-14 Y 1.713". The aiming point is RA =16 27 26.00, Dec = -24 40
> 48.0 in J2000.
> 
> 
> I am interested in the spectrum of a young star ROXs21, which coordinate
> is RA =16 27 19.50 Dec = -24 41 40.1in J2000.
> However, I found inconsitency between RGS data and PN data of the source.
> 
> Each count rate is
> RGS2==>7.3277E-03
> PN==>0.2808
> 
> I checked pimms (heasarc).
> It predicted RGS2 is 1.758E-02 cps when PN is 0.28.
> (Model parameters are ... keV=0.7,Value of nH=0.11e+22)
> 
> Why was my rgs2 data ten times lower?
> 
> Thank you very much,
> 
>             Ai Onikata
> 
> 
> 

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