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From: Christopher Dessert <dessert@umich.edu>
Subject: Source extraction regions with nearby contaminating sources
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From: Christopher Dessert <dessert@umich.edu>
Date: Thu, 9 May 2019 15:59:49 -0400
Subject: Source extraction regions with nearby contaminating sources
To: Jan-Uwe Ness <xmmhelp@sciops.esa.int>
--0000000000002ecd08058879e52b
Content-Type: text/plain; charset="UTF-8"

Hi,

I'm extracting spectra around a bright source in the soft X-rays to perform
a search for hard X-rays from the source (specifically, the target of
observation ID 0165971901). However, when I run edetect_chain I find that
there is a contaminating point source about 47 arcseconds away. This will
definitely contribute to the flux in the source extraction region (for
example, if I extract within 50 arcseconds, approximately the 90%
extraction radius). How should I go about keeping the maximum source flux
but also not extracting much of the contamination? I cannot figure out how
to extract from a region that is a circle around the source minus a circle
around the contamination. I'm also not sure if it is known how to calculate
the encircled energy fraction with this extraction region. Is there a tool
I can use here?

Best,

Chris

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<div dir=3D"ltr"><div>Hi,</div><div><br></div><div>I&#39;m
extracting spect=
ra around a bright source in the soft X-rays to perform a search for hard X=
-rays from the source (specifically, the target of observation ID 016597190=
1). However, when I run edetect_chain I find that there is a contaminating =
point source about 47 arcseconds away. This will definitely contribute to t=
he flux in the source extraction region (for example, if I extract within 5=
0 arcseconds, approximately the 90% extraction radius). How should I go abo=
ut keeping the maximum source flux but also not extracting much of the cont=
amination? I cannot figure out how to extract from a region that is a circl=
e around the source minus a circle around the contamination. I&#39;m also n=
ot sure if it is known how to calculate the encircled energy fraction with =
this extraction region. Is there a tool I can use
here?</div><div><br></div=
><div>Best,</div><div><br></div><div>Chris<br></div></div>

--0000000000002ecd08058879e52b--


Reply 1

Resend
From: Lucia Ballo <xmmhelp@sciops.esa.int>
To: dessert@umich.edu
Subject: Re: Source extraction regions with nearby contaminating sources (PR#84922)
Date: Mon May 13 16:02:26 2019
Dear Chris,

> extraction radius). How should I go about keeping the maximum source flux
> but also not extracting much of the contamination? I cannot figure out how
> to extract from a region that is a circle around the source minus a circle
> around the contamination. I'm also not sure if it is known how to
calculate

SAS supports not only a number of different shapes but also a combination of
them.
For a description of the allowed shapes, of the syntax rules the boolean 
selection expression must adhere to, as well as example expressions, please 
consult the documentation of the SAS package selectlib:

https://xmm-tools.cosmos.esa.int/external/sas/current/doc/selectlib/index.html

For example, the following expression:

circle(x_src,y_src,r_src,X,Y).and..not.circle(x_cont,y_cont,r_cont,X,Y)

should select all the events in a circle of radius r_src centered in
(x_src,y_src) but excluding all the events in a circle of radius r_cont 
centred in (x_cont,y_cont)

We recommend that whenever you create a spatial filter, before you create
a spectrum from it, it might be good to create an image to check that you
indeed selected the correct spatial region.



> around the contamination. I'm also not sure if it is known how to
calculate
> the encircled energy fraction with this extraction region. Is there a tool
> I can use here?

To calculate the encircled energy correction, the SAS task arfgen uses a 
formulation of the PSF (known as the ELLBETA model) that is valid for all 
extraction region shapes.
In case of complex extraction regions (as yours), you need to tell arfgen 
where the centre of the source is actually located (using the parameters 
"sourcex" and "sourcey") so that it can calculate the encircled energy 
correction properly. To do this, you have to call arfgen with the parameter

withsourcepos=true

specifying coordinate system through the parameter "sourcecoords" (four 
coordinate systems can be used: EQPOS, POS, TEL and DET).
For more information, please have a look to the arfgen documentation:

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


I hope that this can help you; otherwise please do not hesitate to contact 
us again.

With kind regards
Lucia


Followup 1

Compose reply
Download message
From: Christopher Dessert <dessert@umich.edu>
Date: Mon, 13 May 2019 11:05:18 -0400
Subject: Re: Source extraction regions with nearby contaminating sources (PR#84922)
To: Lucia Ballo <xmmhelp@sciops.esa.int>
--0000000000003863b90588c63f33
Content-Type: text/plain; charset="UTF-8"

Thanks Lucia--this is very detailed and helpful. I did not know about
selectlib.

Best,

Chris

On Mon, May 13, 2019 at 10:07 AM Lucia Ballo <xmmhelp@sciops.esa.int>
wrote:

> Dear Chris,
>
> > extraction radius). How should I go about keeping the maximum source
flux
> > but also not extracting much of the contamination? I cannot figure out
> how
> > to extract from a region that is a circle around the source minus a
> circle
> > around the contamination. I'm also not sure if it is known how to
> calculate
>
> SAS supports not only a number of different shapes but also a combination
> of
> them.
> For a description of the allowed shapes, of the syntax rules the boolean
> selection expression must adhere to, as well as example expressions,
> please
> consult the documentation of the SAS package selectlib:
>
>
> https://xmm-tools.cosmos.esa.int/external/sas/current/doc/selectlib/index.html
>
> For example, the following expression:
>
> circle(x_src,y_src,r_src,X,Y).and..not.circle(x_cont,y_cont,r_cont,X,Y)
>
> should select all the events in a circle of radius r_src centered in
> (x_src,y_src) but excluding all the events in a circle of radius r_cont
> centred in (x_cont,y_cont)
>
> We recommend that whenever you create a spatial filter, before you create
> a spectrum from it, it might be good to create an image to check that you
> indeed selected the correct spatial region.
>
>
>
> > around the contamination. I'm also not sure if it is known how to
> calculate
> > the encircled energy fraction with this extraction region. Is there a
> tool
> > I can use here?
>
> To calculate the encircled energy correction, the SAS task arfgen uses a
> formulation of the PSF (known as the ELLBETA model) that is valid for all
> extraction region shapes.
> In case of complex extraction regions (as yours), you need to tell arfgen
> where the centre of the source is actually located (using the parameters
> "sourcex" and "sourcey") so that it can calculate the encircled energy
> correction properly. To do this, you have to call arfgen with the parameter
>
> withsourcepos=true
>
> specifying coordinate system through the parameter "sourcecoords" (four
> coordinate systems can be used: EQPOS, POS, TEL and DET).
> For more information, please have a look to the arfgen documentation:
>
> https://xmm-tools.cosmos.esa.int/external/sas/current/doc/arfgen/index.html
>
>
> I hope that this can help you; otherwise please do not hesitate to contact
> us again.
>
> With kind regards
> Lucia
>
> 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).
>
>
>

--0000000000003863b90588c63f33
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div>Thanks Lucia--this is very detailed and
helpful. I di=
d not know about selectlib.</div><div><br></div><div>Best,</div><div><br></=
div><div>Chris<br></div></div><br><div
class=3D"gmail_quote"><div dir=3D"lt=
r" class=3D"gmail_attr">On Mon, May 13, 2019 at 10:07 AM Lucia Ballo
&lt;<a=
 href=3D"mailto:xmmhelp@sciops.esa.int">xmmhelp@sciops.esa.int</a>&gt;
wrot=
e:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px
0px 0px 0=
.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Dear
Chris,<b=
r>
<br>
&gt; extraction radius). How should I go about keeping the maximum source f=
lux<br>
&gt; but also not extracting much of the contamination? I cannot figure out=
 how<br>
&gt; to extract from a region that is a circle around the source minus a ci=
rcle<br>
&gt; around the contamination. I&#39;m also not sure if it is known how
to =
calculate<br>
<br>
SAS supports not only a number of different shapes but also a combination o=
f<br>
them.<br>
For a description of the allowed shapes, of the syntax rules the boolean <b=
r>
selection expression must adhere to, as well as example expressions, please=
 <br>
consult the documentation of the SAS package selectlib:<br>
<br>
<a href=3D"https://xmm-tools.cosmos.esa.int/external/sas/current/doc/select=
lib/index.html" rel=3D"norefer

Message of length 8000 truncated


Followup 2

Compose reply
Download message
From: Christopher Dessert <dessert@umich.edu>
Date: Wed, 5 Jun 2019 05:15:06 -0400
Subject: Re: Source extraction regions with nearby contaminating sources (PR#84922)
To: Lucia Ballo <xmmhelp@sciops.esa.int>
--0000000000001cc64e058a900829
Content-Type: text/plain; charset="UTF-8"

Hi Lucia,

Thanks for your previous help. I have a followup question. I am attempting
to input the source center coordinates in arfgen as mentioned above. To do
this, I was using the coordinates directly listed in the region file (RA
and Dec corresponding to the TCRVL2 and TCRVL3 keywords). However when I do
this (i.e., using these RA and Dec with sourcecoords=eqpos) the effective
area is several orders of magnitude too small. I discovered that these are
somehow in the wrong coordinate system , because if I use ds9 to tell me
these coordinates in ICRS, I get different RA and Dec. If I use these new
RA and Dec with arfgen sourcecoords=eqpos, the effective area comes out
correctly. I'm looking at several sources and would prefer not to do this
manually in each case. How can I convert the RA and Dec in the region file
to the ICRS RA and Dec? Or what options do I need to use to use the region
RA and Dec directly with arfgen?

Best,

Chris

On Mon, May 13, 2019 at 11:05 AM Christopher Dessert <dessert@umich.edu>
wrote:

> Thanks Lucia--this is very detailed and helpful. I did not know about
> selectlib.
>
> Best,
>
> Chris
>
> On Mon, May 13, 2019 at 10:07 AM Lucia Ballo <xmmhelp@sciops.esa.int>
> wrote:
>
>> Dear Chris,
>>
>> > extraction radius). How should I go about keeping the maximum
source
>> flux
>> > but also not extracting much of the contamination? I cannot figure
out
>> how
>> > to extract from a region that is a circle around the source minus
a
>> circle
>> > around the contamination. I'm also not sure if it is known how to
>> calculate
>>
>> SAS supports not only a number of different shapes but also a
combination
>> of
>> them.
>> For a description of the allowed shapes, of the syntax rules the
boolean
>> selection expression must adhere to, as well as example expressions,
>> please
>> consult the documentation of the SAS package selectlib:
>>
>>
>> https://xmm-tools.cosmos.esa.int/external/sas/current/doc/selectlib/index.html
>>
>> For example, the following expression:
>>
>> circle(x_src,y_src,r_src,X,Y).and..not.circle(x_cont,y_cont,r_cont,X,Y)
>>
>> should select all the events in a circle of radius r_src centered in
>> (x_src,y_src) but excluding all the events in a circle of radius r_cont
>> centred in (x_cont,y_cont)
>>
>> We recommend that whenever you create a spatial filter, before you
create
>> a spectrum from it, it might be good to create an image to check that
you
>> indeed selected the correct spatial region.
>>
>>
>>
>> > around the contamination. I'm also not sure if it is known how to
>> calculate
>> > the encircled energy fraction with this extraction region. Is
there a
>> tool
>> > I can use here?
>>
>> To calculate the encircled energy correction, the SAS task arfgen uses
a
>> formulation of the PSF (known as the ELLBETA model) that is valid for
all
>> extraction region shapes.
>> In case of complex extraction regions (as yours), you need to tell
arfgen
>> where the centre of the source is actually located (using the
parameters
>> "sourcex" and "sourcey") so that it can calculate the encircled energy
>> correction properly. To do this, you have to call arfgen with the
>> parameter
>>
>> withsourcepos=true
>>
>> specifying coordinate system through the parameter "sourcecoords" (four
>> coordinate systems can be used: EQPOS, POS, TEL and DET).
>> For more information, please have a look to the arfgen documentation:
>>
>>
>> https://xmm-tools.cosmos.esa.int/external/sas/current/doc/arfgen/index.html
>>
>>
>> I hope that this can help you; otherwise please do not hesitate to
>> contact
>> us again.
>>
>> With kind regards
>> Lucia
>>
>> 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).
>>
>>
>>

--0000000000001cc64e058a900829
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div>Hi
Lucia,</div><div><br></div><div>Thanks for your
pr=
evious help. I have a followup questi

Message of length 11445 truncated


Reply 2

Resend
From: Lucia Ballo <xmmhelp@sciops.esa.int>
To: dessert@umich.edu
Subject: Re: Source extraction regions with nearby contaminating sources (PR#84922)
Date: Fri Jun  7 15:35:39 2019
Dear Chris,

In order to better assist you, could you please tell me what region file 
are you referring to, and clarify me how are you using the TCRVLs keywords 
reported in the event files to derive the coordinates of your source?

Many thanks in advance.
With kind regards,
Lucia

Up to top level
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