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From: elifnurozel@gmail.com
Subject: Calculating areas of point sources
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Date: Sat, 24 Aug 2013 09:17:57 GMT
From: elifnurozel@gmail.com
To: xmmhelp@sciops.esa.int
Cc: elifnurozel@gmail.com
Subject: Calculating areas of point sources
Full_Name: Elifnur .zel
Submission from: (NULL) (88.230.31.231)


Hi,

I would like to calculate the areas of point sources. But, in the source
detection  method, "sourceradius" parameter is same for all sources.. How can I
obtain the radius (or area) of each point source?

Thanks a lot,

Elifnur .zel


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Date: Mon, 26 Aug 2013 17:30:22 +0200
From: Nora Loiseau <Nora.Loiseau@sciops.esa.int>
To: Jan-Uwe Ness <xmmhelp@sciops.esa.int>
Subject: Re: Calculating areas of point sources (PR#24)
This is a multi-part message in MIME format.
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Dear Jan-Uwe,

due to the strange reset of Jitterbug numbers this message appeared as
a followup of an XSA_OLD message.

Do you want me to move it to "Pending" ?

Cheers,

Nora

------------------------------------
Dear Sir / Madam,

I'm a postgraduate student in Department of Astronomy and Space Sciences; Ankara

University, Turkey.
My thesis is based on the XMM-Newton observations of two galaxy clusters: Abell 
1991 and Abell 2142.

I mean, e.g. for Abell 1991, I'm trying to obtain the hardness ratio of each 
source individually. So, I need to find and mark their boundaries, but there's a

lot of sources (galaxies or other objects), so I can't mark them manually and 
besides, if I make this job manually, contours will be rule of thumb! In "Source

detection" method neither edetect_chain nor srcdisplay tasks have a special 
parameter to "contour" these sources (srcdisplay task have a parameter which is 
called "sourceradii", but I don't want 'circles', and value of this parameter is

totally up to user). I want to know whether there's a parameter for this purpose

or not.

(Afterwards, I'll calculate total count rates within these contours.)

Many thanks,
(Ms.) Elifnur .ZEL


2013/8/25 Jan-Uwe Ness <xmmhelp@sciops.esa.int
<mailto:xmmhelp@sciops.esa.int>>

    Dear Elifnur .zel,

      Given the limited resources available to the XMM-Newton project,
        the helpdesk can only respond to questions that can be verified
        as coming from professionals in the scientific community.
        Therefore, before answering your question, and for any future
        queries you may have, we kindly ask you to reply to this
        message providing us with your title (Mr/Ms/Dr/Prof etc),
        full name and surname, professional status and affiliation.
        This also helps us to track what types of queries we receive
        from where.

        We apologize for any inconvenience

    Once verified, please specify what exactly you need. A point source by
    definition has a radius (or area) zero, and I don't understand the objective
of
    your question.

    Since no instrument can be perfect, the photons from a point source are
always
    distributed over a certain area. The way this happens is described by the
point
    spread function (=PSF) that depends on the instrument but not on the
properties
    of the source itself.

    You have not indicated which tool you are using that uses the parameter
    "sourceradius", perhaps this parameter refers to the size of the extraction
    region. The SAS tool eregionanalyse opimizes the size of the extraction
region
    to collect as much signal as possible while keeping the background as low as
    possible. A description can be found under:
    http://xmm.esac.esa.int/sas/current/doc/eregionanalyse/index.html
    The optimal size can depend on the distance from the center of the chip as
the
    PSF is broader towards the edges of the CCD.

    If that is not what you mean, please specify how else we can help you.

      Thanks,
    Jan-Uwe Ness


     >
     > Hi,
     >
     > I would like to calculate the areas of point sources. But, in the
source
     > detection  method, "sourceradius" parameter is same for all sources..
How can
    I
     > obtain the radius (or area) of each point source?
     >
     > Thanks a lot,
     >
     > Elifnur .zel
     >


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<html>
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    <meta http-equiv="content-type" content="text/html;
charset=ISO-8859-1">
  </head>
  <body text="#000000" bgcolor="#FFFFFF">
    <div dir="ltr">
      <div>
        <div>
          <div>Dear Jan-Uwe,<br>
            <br>
            due to the strange reset of Jitterbug numbers this message
            appeared as<br>
            a followup of an XSA_OLD message.<br>
            <br>
            Do you want me to move it to "Pending" ? <br>
            <br>
            Cheers,<br>
            <br>
            Nora<br>
            <br>
            ------------------------------------<br>
            Dear Sir / Madam,<br>
            <br>
         

Message of length 11246 truncated


Reply 1

Resend
From: Jan-Uwe Ness <xmmhelp@sciops.esa.int>
To: elifnurozel@gmail.com
Subject: Re: Calculating areas of point sources (PR#24)
Date: Sat Aug 24 22:52:50 2013
Dear Elifnur .zel,

 Given the limited resources available to the XMM-Newton project,
   the helpdesk can only respond to questions that can be verified
   as coming from professionals in the scientific community.
   Therefore, before answering your question, and for any future
   queries you may have, we kindly ask you to reply to this
   message providing us with your title (Mr/Ms/Dr/Prof etc),
   full name and surname, professional status and affiliation.
   This also helps us to track what types of queries we receive
   from where.

   We apologize for any inconvenience

Once verified, please specify what exactly you need. A point source by
definition has a radius (or area) zero, and I don't understand the objective of
your question.

Since no instrument can be perfect, the photons from a point source are always
distributed over a certain area. The way this happens is described by the point
spread function (=PSF) that depends on the instrument but not on the properties
of the source itself.

You have not indicated which tool you are using that uses the parameter
"sourceradius", perhaps this parameter refers to the size of the extraction
region. The SAS tool eregionanalyse opimizes the size of the extraction region
to collect as much signal as possible while keeping the background as low as
possible. A description can be found under:
http://xmm.esac.esa.int/sas/current/doc/eregionanalyse/index.html
The optimal size can depend on the distance from the center of the chip as the
PSF is broader towards the edges of the CCD.

If that is not what you mean, please specify how else we can help you.

 Thanks,
Jan-Uwe Ness


> 
> Hi,
> 
> I would like to calculate the areas of point sources. But, in the source
> detection  method, "sourceradius" parameter is same for all sources.. How
can
I
> obtain the radius (or area) of each point source?
> 
> Thanks a lot,
> 
> Elifnur .zel
> 

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