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From: Yasushi Ikebe <ikebe@milkyway.gsfc.nasa.gov>
Subject: Offset among EPIC cameras
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2 followups: 1 2

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Date: Mon, 02 Feb 2004 14:43:19 -0500 (EST)
To: xmmhelp@xmm.vilspa.esa.es
Subject: Offset among EPIC cameras
From: Yasushi Ikebe <ikebe@milkyway.gsfc.nasa.gov>
Dear XMM help desk,

Could you provide information on the mutual offset among
different CCD cameras?
What I am trying to do now is overlaying MOS1 and MOS2 images
onto PN image on the detector coordinate (DETX, DETY).
MOS1 and MOS2 coordinates are rotated by 90 and 180 degrees from
that of PN, respectively, and there are offset as well.
How can I perform the rotation + pararel shift operations?

Yasushi

-----------------------------------------------------------------
Yasushi Ikebe Dr.

Office:
Code 661, NASA/Goddard Space Flight Center,
Greenbelt Rd., Greenbelt, MD, 20771, USA
TEL: 301-286-0680
FAX: 301-286-1682

Employer:
Joint Center for Astrophysics, Physics Department,
University of Maryland, Baltimore County, 
1000 Hilltop Circle, Baltimore, MD, 21250, USA
-----------------------------------------------------------------


Reply 1

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From: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
To: ikebe@milkyway.gsfc.nasa.gov
Subject: Re: Offset among EPIC cameras (PR#10095)
Date: Tue Feb  3 17:02:15 2004
Dear Yasushi,

I contacted an expert with respect
to your questions. Unfortunately,
this procedure will cause a delay.

With best regards
Norbert


Reply 2

Resend
From: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
To: ikebe@milkyway.gsfc.nasa.gov
Subject: Re: Offset among EPIC cameras (PR#10095)
Date: Wed Feb  4 15:42:26 2004
Dear Yasushi,

we have this information not available.

Each camera is calibrated with respect to
the sky. For merging of images in
detector coordinates it should be kept
in mind that the seven CCDs of each MOS
camera are not based on a single wafer.

I would strongly suggest to work with
sky images for any overlay.

With best regards
Norbert 


Followup 1

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Date: Wed, 04 Feb 2004 12:34:43 -0500 (EST)
To: xmmhelp@xmm.vilspa.esa.es
Subject: Re: Offset among EPIC cameras (PR#10095)
From: Yasushi Ikebe <ikebe@milkyway.gsfc.nasa.gov>
Dear Norbert ,

Thanks for the reply.
Let me ask another question.
Does (DETX, DETY) value of each photon represent
the detected position on the focal plane correctly?
If not, that means an angular distance between two point sources
measured from a DETX-DETY image is wrong.
If this is the case, everything in my analysis will be screwed up.

regards,
Yasushi


From: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
Subject: Re: Offset among EPIC cameras (PR#10095)
Date: Wed, 4 Feb 2004 15:42:25 GMT

> Dear Yasushi,
> 
> we have this information not available.
> 
> Each camera is calibrated with respect to
> the sky. For merging of images in
> detector coordinates it should be kept
> in mind that the seven CCDs of each MOS
> camera are not based on a single wafer.
> 
> I would strongly suggest to work with
> sky images for any overlay.
> 
> With best regards
> Norbert 
> 


-----------------------------------------------------------------
Yasushi Ikebe Dr.

Office:
Code 661, NASA/Goddard Space Flight Center,
Greenbelt Rd., Greenbelt, MD, 20771, USA
TEL: 301-286-0680
FAX: 301-286-1682

Employer:
Joint Center for Astrophysics, Physics Department,
University of Maryland, Baltimore County, 
1000 Hilltop Circle, Baltimore, MD, 21250, USA
-----------------------------------------------------------------



Reply 3

Resend
From: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
To: ikebe@milkyway.gsfc.nasa.gov
Subject: Re: Offset among EPIC cameras (PR#10095)
Date: Thu Feb  5 17:19:54 2004
Dear Yasushi,

the focal plane of XMM-Newton's mirrors
is a sphere. 

The MOS cameras are modulating the shape, 
i.e. the outer CCDs are mounted above the 
central one. However, each CCD by itself 
is plane. As pn CCDs are on a single wafer 
the sphere can not be modeled by the camera.

As the field of view is very small, I assume
the distances measured in detector coordinates
will not differ much from the distances 
measured in sky coordinates.

With best regards
Norbert


Followup 2

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Date: Thu, 05 Feb 2004 12:41:19 -0500 (EST)
To: xmmhelp@xmm.vilspa.esa.es
Subject: Re: Offset among EPIC cameras (PR#10095)
From: Yasushi Ikebe <ikebe@milkyway.gsfc.nasa.gov>
Hi,

I probably should have asked in rather different way.
What is the DETX-DETY coordinate system then?

For PN, is (DETX, DETY) represents the physical position
where the photon hit the CCD?
Or, is it a tangential plane projection of the spherical coordinate?

In another words, when (DETX, DETY) is converted to (X, Y),
are there any other operation is performed than
a rotation and a parallel shift?

yasushi


From: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
Subject: Re: Offset among EPIC cameras (PR#10095)
Date: Thu, 5 Feb 2004 17:19:53 GMT

> Dear Yasushi,
> 
> the focal plane of XMM-Newton's mirrors
> is a sphere. 
> 
> The MOS cameras are modulating the shape, 
> i.e. the outer CCDs are mounted above the 
> central one. However, each CCD by itself 
> is plane. As pn CCDs are on a single wafer 
> the sphere can not be modeled by the camera.
> 
> As the field of view is very small, I assume
> the distances measured in detector coordinates
> will not differ much from the distances 
> measured in sky coordinates.
> 
> With best regards
> Norbert
> 



Reply 4

Resend
From: Norbert Schartel <xmmhelp@xmm.vilspa.esa.es>
To: ikebe@milkyway.gsfc.nasa.gov
Subject: Re: Offset among EPIC cameras (PR#10095)
Date: Fri Feb  6 14:38:55 2004
Dear Yasushi,

I assume that I confused you much more than
I was helpful. I hope that the situation
will improve.

The provided sky coordinates are a tangential
plane projection. The ds9 makes the
conversion into the sphere when providing
RA and DEC.

The geometrical effects, i.e. location of
CCDs with respect to each other are already
taken into account when the detector coordinates
are calculated. The values are given in the
CCFs (LINCOORD) which give the relative orientations
with respect to each other. I send you a part
of a document with is actually under preparation
in which the values are described. (As I can
not attach gzipped ps files within the HelpDesk,
I will send the files from my "private" account.)

With best regards
Norbert   

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