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From: Christopher Dessert <dessert@umich.edu>
Subject: ARFs and Vignetting
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1 followups: 1

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From: Christopher Dessert <dessert@umich.edu>
Date: Sun, 30 Sep 2018 22:17:53 -0400
Subject: ARFs and Vignetting
To: Jan-Uwe Ness <xmmhelp@sciops.esa.int>
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Hi,

I am analyzing some EPIC observations and would like to know if the
vignetting effects are included in the effective area given in the ARF
file. I am confused because in the files *-exp-im.fits it seems that the
vignetting is thought of as affecting the exposure time, while if it is
taken into account in the ARF file then it is thought of as affecting the
effective area. What is the proper way to calculate the quantity with units
cm^2*s when calculating flux from counts?

Thanks,

Chris

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<div dir=3D"ltr"><div>Hi,</div><div><br></div><div>I
am analyzing some EPIC=
 observations and would like to know if the vignetting effects are included=
 in the effective area given in the ARF file. I am confused because in the =
files *-exp-im.fits it seems that the vignetting is thought of as affecting=
 the exposure time, while if it is taken into account in the ARF file then =
it is thought of as affecting the effective area. What is the proper way to=
 calculate the quantity with units cm^2*s when calculating flux from counts=
?</div><div><br></div><div>Thanks,</div><div><br></div><div>Chris<br></div>=
</div>

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Reply 1

Resend
From: Rosario Gonzalez Riestra <xmmhelp@sciops.esa.int>
To: dessert@umich.edu
Subject: Re: ARFs and Vignetting (PR#84042)
Date: Mon Oct  1 09:13:54 2018
Dear Dr. Dessert

Vignetting  is fully taken into account when computing the affective area,
unless its 
computation is explicitly  disabled. Please refer to the description of the task
at:

http://xmm-tools.cosmos.esa.int/external/sas/current/doc/arfgen/arfgen.html

The output of this task, that is in cm2, is what has to be used to go from
counts to flux.


Regards

Rosario Gonzalez-Riestra
XMM-SOC User Support Group
 


Followup 1

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From: Christopher Dessert <dessert@umich.edu>
Date: Mon, 1 Oct 2018 16:45:58 -0400
Subject: Re: ARFs and Vignetting (PR#84042)
To: Rosario Gonzalez Riestra <xmmhelp@sciops.esa.int>
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Content-Type: text/plain; charset="UTF-8"

Hi Rosario,

Thanks. Does this vignetting factor account for how the form of vignetting
changes over energy? In
https://heasarc.gsfc.nasa.gov/docs/xmm/sas/help/arfgen.pdf equation (1) in
section 10.2 says that the mirror area (including vignetting) does not
depend on the energy.

Best,

Chris

On Mon, Oct 1, 2018 at 5:13 AM, Rosario Gonzalez Riestra <
xmmhelp@sciops.esa.int> wrote:

>
> Dear Dr. Dessert
>
> Vignetting  is fully taken into account when computing the affective area,
> unless its
> computation is explicitly  disabled. Please refer to the description of
> the task
> at:
>
> http://xmm-tools.cosmos.esa.int/external/sas/current/doc/
> arfgen/arfgen.html
>
> The output of this task, that is in cm2, is what has to be used to go from
> counts to flux.
>
>
> Regards
>
> Rosario Gonzalez-Riestra
> XMM-SOC User Support Group
>
>
> This message is intended only for the recipient(s) named above. It may
> contain proprietary information and/or
> protected content. Any unauthorised disclosure, use, retention or
> dissemination is prohibited. If you have received
> this e-mail in error, please notify the sender immediately. ESA applies
> appropriate organisational measures to protect
> personal data, in case of data privacy queries, please contact the ESA
> Data Protection Officer (dpo@esa.int).
>
>
>

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<div dir=3D"ltr"><div dir=3D"ltr"><div>Hi
Rosario,</div><div><br></div><div=
>Thanks. Does this vignetting factor account for how the form of vignetting=
 changes over energy? In <a href=3D"https://heasarc.gsfc.nasa.gov/docs/xmm/=
sas/help/arfgen.pdf">https://heasarc.gsfc.nasa.gov/docs/xmm/sas/help/arfgen=
.pdf</a> equation (1) in section 10.2 says that the mirror area (including
=
vignetting) does not depend on the
energy.</div><div><br></div><div>Best,</=
div><div><br></div><div>Chris<br></div></div></div><div
class=3D"gmail_extr=
a"><br><div class=3D"gmail_quote">On Mon, Oct 1, 2018 at 5:13 AM,
Rosario G=
onzalez Riestra <span dir=3D"ltr">&lt;<a
href=3D"mailto:xmmhelp@sciops.esa.=
int" target=3D"_blank">xmmhelp@sciops.esa.int</a>&gt;</span>
wrote:<br><blo=
ckquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #c=
cc solid;padding-left:1ex"><br>
Dear Dr. Dessert<br>
<br>
Vignetting=C2=A0 is fully taken into account when computing the affective a=
rea,<br>
unless its <br>
computation is explicitly=C2=A0 disabled. Please refer to the description o=
f the task<br>
at:<br>
<br>
<a href=3D"http://xmm-tools.cosmos.esa.int/external/sas/current/doc/arfgen/=
arfgen.html" rel=3D"noreferrer" target=3D"_blank">http://xmm-tools.cosmos.e=
sa.<wbr>int/external/sas/current/doc/<wbr>arfgen/arfgen.html</a><br>
<br>
The output of this task, that is in cm2, is what has to be used to go from<=
br>
counts to flux.<br>
<br>
<br>
Regards<br>
<br>
Rosario Gonzalez-Riestra<br>
XMM-SOC User Support Group<br>
<div class=3D"HOEnZb"><div class=3D"h5">=C2=A0<br>
<br>
This message is intended only for the recipient(s) named above. It may cont=
ain proprietary information and/or<br>
protected content. Any unauthorised disclosure, use, retention or dissemina=
tion is prohibited. If you have received<br>
this e-mail in error, please notify the sender immediately. ESA applies app=
ropriate organisational measures to protect<br>
personal data, in case of data privacy queries, please contact the ESA Data=
 Protection Officer (<a
href=3D"mailto:dpo@esa.int">dpo@esa.int</a>).<br>
<br>
<br>
</div></div></blockquote></div><br></div>

--000000000000849a2f057730e4dc--



Reply 2

Resend
From: Rosario Gonzalez Riestra <xmmhelp@sciops.esa.int>
To: dessert@umich.edu
Subject: Re: ARFs and Vignetting (PR#84042)
Date: Tue Oct  2 08:41:09 2018
Hi Chris,

Yes, the vignetting factor does depend on the energy, see

https://xmm-tools.cosmos.esa.int/external/xmm_user_support/documentation/uhb/effareaoffaxis.html

This effect is taken into account by 'arfgen' when computing the effective
area.

Rosario

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