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XMM­Newton CCF Release Note
XMM­CCF­REL­26
Effective area of the X­ray telescopes
P. Gondoin
October 5, 2000
1 CCF components
Name of CCF VALDATE List of Blocks
changed
CAL VERSION XSCS flag
XRT1 XAREAEF 0007 2000­01­13T00:00:00 ONAXISXAREAEF,
VIGNETTING
Cal 3.80, xmm­
sas 20000903 1900
NO
XRT2 XAREAEF 0008 2000­01­13T00:00:00 ONAXISXAREAEF,
VIGNETTING
Cal 3.80, xmm­
sas 20000903 1900
NO
XRT3 XAREAEF 0007 2000­01­13T00:00:00 ONAXISXAREAEF,
VIGNETTING
Cal 3.80, xmm­
sas 20000903 1900
NO
2 Changes
For technical reason, an artificial point was added at 0 eV in the on­axis effective area table.
3 Scientific Impact of this Update
This update has no impact on the on­axis effective area accuracy in the 100 eV to 20 keV band but
is only provided for technical reasons.
4 Estimated Scientific Quality
The scientific quality of the refered CCF is identical to the previous release.
1

XMM­Newton CCF Release XMM­CCF­REL­26 Page: 2
4.1 Numerical model accuracy
The in­orbit effective area of the CCF files were generated using scisim in combination with a
numerical model of the x­ray telescopes [2]. The accuracy of the CCF files can be estimated by
comparing on­ground calibration test measurements with simulation results [3]. Note however that
on­ground calibration tests could not be performed in fully representative conditions. On­axis
effective area (see Fig.1) were measured on mirror modules without x­ray baffles using sources
located at a finite distance. The vignetting function of one telescope equipped with x­ray baffles
was measured in a collimated beam in EUV at 58 nm (see Fig.2).
100 1000 10000
Energy (eV)
0
200
400
600
800
1000
1200
1400
Ae
(cm2)
Effective area of the XMM mirror modules at PANTER
ideal Wolter
FM1 numerical model
FM1 measurements
FM2 measurements
FM3 measurements
FM4 measurements
Figure 1: X­ray measurement and simulation of the on­axis effective area at PANTER
4.2 In­orbit calibration verification
The simulation results indicates calibration accuracy of the effective area on­axis better than 5 %
over most of the XMM spectral range. A possible exception, however, is the gold M absorption edge
due to the use of discrete spectral lines for effective area measurements on­ground.
Within the in­flight calibration programme, bright BL Lac objects with hard spectra were ob­
served to obtain continuum emission spectra in the 2.2 to 3.4 keV range of the Au M absorption
edges [4]. Their lineless continuum emission is well suited to map the edge discontinuities of the
telescopes and instruments effective area. Fig.3 shows spectra of the MS1229.2+6430 BL Lac object
obtained with the MOS cameras through thin Al filters. These spectra were fitted with single power
law models plus a photo­electric absorption. The fit were performed using the XSPEC software
package in combination with response matrix files identical for the two MOS cameras. These re­
sponse files include effective area calibration files of the x­ray telescopes. No excess residuals to the
fitting curve are observed around the 2.2 keV location of the Au M edge.

XMM­Newton CCF Release XMM­CCF­REL­26 Page: 3
-20 -15 -10 -5 0 5 10 15 20
(arcmin)
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
Relative effective area of FM1 mirror module with X-ray baffles
Measurements at 58 nm
Simulation (using sieves design)
Simulation (using sieves metrology)
Figure 2: EUV measurement and simulation of the vignetting function at CSL
In order to verify the effective area variation over the EPIC field of view, the G21.5­0.9 supernova
remnant was observed on­axis and at four off­axis positions [4, 5]. The 10 arcmin off­axis pointings
in orthogonal direction were used in particular to verify the azimuthal variation of the vignetting
function produced by the RGA assemblies. Indeed, the stack of gratings located behind the FM3
and FM4 telescopes acts as a Venitian blind. Due to the grating plane inclination with respect to the
telescope optical axis, the vignetting function in the EPIC detector plane is modulated azimuthaly
with the highest effective area in the RGA dispersion direction. Fig.4 show that the measurements
confirm the azimuthal modulation of the vignetting function. At 10 arcmin off­axis angle, they are
within 10% of the vignetting calculation using the present description of the RGA vignetting.

XMM­Newton CCF Release XMM­CCF­REL­26 Page: 4
Figure 3: MOS 1 and 2 spectra of the MS1229.2+6430 BL Lac object including spectral fit residuals
to a power law model with an absorbed column density.
-15 -12 -9 -6 -3 0 3 6 9 12 15
Field angle (arcmin)
0
0.2
0.4
0.6
0.8
1
Vignetting
factor
Meas. in RGA disp. direction
Meas. in cross disp. direction
Figure 4: Angle dependance of the telescope plus RGA vignetting function below 4.5 keV in azimuth
respectively parallel (continuous line) and perpendicular to the RGA dispersion.

XMM­Newton CCF Release XMM­CCF­REL­26 Page: 5
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. http://xmm.vilspa.esa.es/calibration/docs/general/calhb.ps.gz.
[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
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: II. Effective Area. In SPIE Proc.,
volume 3444, page 290, 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.
[5] D.M. Neumann. Report of the in­flight vignetting calibration of the MOS cameras aboard the
XMM­Newton satellite. , CEA/Saclay, August 2000.