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XMM­Newton CCF Release Note
XMM­CCF­REL­2
Point Spread Function of the X­ray telescopes
P. Gondoin
October 4, 2000
1 CCF components
Name of CCF VALDATE Blocks changed CAL VERSION XSCS flag
XRT1 XPSF 0006 2000­01­13T00:00:00 ALIGNMENT,
FIT PAR,
3GAUSS PAR,
IMAGE
sas 20000903 1900 NO
XRT2 XPSF 0002 2000­01­13T00:00:00 ALIGNMENT,
FIT PAR,
3GAUSS PAR,
IMAGE
sas 20000903 1900 NO
XRT3 XPSF 0002 2000­01­13T00:00:00 ALIGNMENT,
FIT PAR,
3GAUSS PAR,
IMAGE
sas 20000903 1900 NO
2 Changes
The files describe the PSFs of the flight x­ray telescopes XRT1, XRT2 and XRT3 vs energy and field
angle. The XRT1, XRT2 and XRT3 telescopes are respectively associated with the MOS1, MOS2
and PN EPIC cameras. Each file consists of a header, three table sections and an image library
section [1].
ffl the alignment table contains coefficients which describe the EPIC defocus and decenter with
respect to the average focal point of the mirror modules.
ffl a second table section contains a three dimensional table of 6 fitting coefficients provided as
a function of 6 energies and 6 field angles. These coefficient are used by the CCF access layer
to generate analytical PSF descriptions using a simple bi­dimensional Gaussian fit.
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XMM­Newton CCF Release XMM­CCF­REL­2 Page: 2
ffl a third section contains a table of 21 fitting coefficients. These coefficient are used by the CCF
access layer to generate analytical PSF descriptions using a bi­dimensional multi­Gaussian fit.
ffl the image section contains a collection of FITS images obtained at different energies and
field angles. Theses images are interpolated by the CCF access layer to any energy and field
position.
3 Scientific Impact of this Update
The released CCF sections update the previous Pearson VII model which provided a PSF description
limited to the center of the field of view and to low energies.
4 Estimated Scientific Quality
ffl The simple bi­dimensional Gaussian model of the x­ray telescope PSFs provides an effective
way to construct representative XMM­Newton PSFs for applications (e.g source detections)
which do not require high spatial or photometric accuracies.
ffl The validity range of the bi­dimensional multi­Gaussian fit of the telescope PSF is limited
to the central 10 arcmin of the field of view and to energies lower than 4.5 keV. Within
this domain, the encircled energy funtion is estimated to be accurate to better than 5 % for
extraction window radii included between 20 arcsec and 2 arcmin (see Fig.3)
ffl The image section of the CCF files contains a library of FITS images which were generated
using scisim in combination with a numerical model of the x­ray telescopes [2]. In­orbit
calibration verifications (see fig.1) indicates that the in­orbit telescope PSFs are identical to
the on­ground measurements [3] [4]. Hence, the accuracy of the FITS files provided in the
CCF image library can be estimated by comparing on­ground calibration test measurements
with simulation results. Figure 2 indicates that simulated encircled energy functions at 1.5
keV agree with on­axis PANTER measurements to an accuracy better than 3 % accuracy. The
accuracy at 8 keV then degrades to about 5 % for a 30 arcsec radius of the extraction window.
The PSF core of the XRT1 and XRT3 telescopes at low energies exhibit a triangular shape
which is not describe by the numerical model. A more accurate description of the core of the
telescope PSFs is provided by the multi­Gaussian fit.
References
[1] Christian Erd, Phillipe Gondoin, David Lumb, Rudi Much, Uwe Lammers, and Giuseppe Va­
canti. Calibration Access and Data Handbook. XMM­PS­GM­20, issue 1.0, ESA/SSD, September
2000.
[2] Ph. Gondoin, B. Aschenbach, H. Brauninger, D. de Chambure, J.P. Colette, R. Egger, K. van
Katwijk, D. Lumb, A. Peacock, Y. Stockmann, J.P. Tock, and R. Willingale. Simulation of

XMM­Newton CCF Release XMM­CCF­REL­2 Page: 3
0 30 60 90 120 150 180
arcsec
10 -5
10 -4
10 -3
10 -2
10 -1
10
Point Spread Function of XMM FM3 Telescope
In orbit (MOS1 w2+w3)
On ground (PANTER CCD)
0 30 60 90 120 150
arcsec
10 -5
10 -4
10 -3
10 -2
10 -1
10 0
RPSF
In orbit EPIC MOS 2
On ground Panter CCD
Figure 1: PSF of the XRT1 (left) and XRT2 (right) telescope measured with the MOS1 and MOS2
camera operating respectively in window and full frame mode. The radial energy distributions of
the PSFs measured in­orbit are identical to on­ground measurements within the accuracy limit of
background substraction.
the XMM Mirror Performance based on Metrology Data. In SPIE Proc., volume 2808, pages
390--401, 1996.
[3] Ph. Gondoin, B. Aschenbach, M. Beijersbergen, R. Egger, F. Jansen, Y. Stockman, and J.P.
Tock. Calibration of the first XMM flight mirror module: I. Image Quality. In SPIE Proc.,
volume 3444, page 278, 1998.
[4] Ph. Gondoin, B. Aschenbach, C. Erd, D.Lumb, S. Majerowicz, D. Neumann, and J.L.Sauvageot.
In­orbit calibration of the XMM­Newton telescopes. In SPIE Proc., 2000.

XMM­Newton CCF Release XMM­CCF­REL­2 Page: 4
0 30 60 90 120
arcseconds
0.0
0.2
0.4
0.6
0.8
1.0
Encircled energy of the XMM Mirror Modules at PANTER
simulation with FM1 numerical model
1.5 keV CCD measurements of FM2
1.5 keV CCD measurements of FM3
0.0 30.0 60.0 90.0 120.0
arcseconds
0.0
0.2
0.4
0.6
0.8
1.0
Encircled energy of the XMM Mirror Modules at PANTER
simulation with FM1 numerical model
8.0 keV CCD measurements of FM2
8.0 keV CCD measurements of FM3
Figure 2: Encircled energy functions of the XRT3 (FM2 module) and XRT1 (FM3 module) telescopes
measured at Panter respectively at 1.5 keV (left) and 8 keV (right). The measurements are compared
with simulation results using the numerical model which was used to build the PSF image library
in the CCF files.
0 10 20 30 40 50 60
pixels
0.0
0.2
0.4
0.6
0.8
1.0
EEF
FM3 + MOS1 meas.
3 Gaussian fit
0 30 60 90 120
pixels
0.0
0.2
0.4
0.6
0.8
1.0
RPSF
FM4 + MOS2
3 Gaussian fit
Figure 3: Encircled energy functions of the XRT1 and XRT2 telescopes measured in­orbit. The
measurements are compared with the multi­Gaussian analytical fit which parameters are provided
in the CCF files.