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Status of the EPIC/MOS Calibration

P.Ferrando, A.F. Abbey, M. Arnaud, P. Bennie, M. Dadina, M. Denby, S. Ghizzardi, G. Griffiths, N. La Palombara, D. Lumb, S. Molendi, D. Neumann, J.L. Sauvageot, R. Saxton, S. Sembay, A. Tiengo, M. Turner

EPIC + SSC + ESA team

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


Instrument overview

Hardware and calibration items

Telescope · On axis effective area · PSF · Vignetting Grating Stack · Transmission · Azimuthal modulation

MOS Cameras Filters : 2 thin, 1 medium, 1 thick · Transmission · Homogeneity CCDs : 7 with 600 â 600 pixels of size 1.1 arcsec2 · Quantum efficiency · Background · Charge transfer inefficiency · Metrology · Redistribution matrix · Homogeneity · Energy scale · Timing · Pile-up
EPIC/MOS Cal. Status

XMM-Newton Instrumen t Calibration Workshop


Instrument overview

Basic EPIC/MOS modes

Large Window
Frame time (sync) 0.9 s central CCD 2.7 s outer CCDs

Small Window
Frame time (sync) 0.3 s central CCD 2.7 s outer CCDs

Timing
Time resolution : 1.8 ms central CCD Frame time 2.6 s outer CCDs
EPIC/MOS Cal. Status

Full Frame
Frame time : 2.6 s

XMM-Newton Instrumen t Calibration Workshop


Input for calibration files

Main input for calibration values
Item Ground Telescope Effective area X PSF Vignetting Gratings Transmission X Azimuthal modulation X Filters Transmission X Homogeneity X CCDs Quantum efficiency X Charge Transf. Ineffic. Redistribution matrix X Homogeneity X Background Metrology, astrometry Timing
XMM-Newton Instrumen t Calibration Workshop

Flight X X

Workshop P P P P

X X X X X X

P P P P P P

EPIC/MOS Cal. Status


Metrology

Metrology
(Mike Denby et al.) · Done with Lockman Hole, NGC 2516, and Orion Molecular Cloud fields · Compare X-ray source positions derived with SAS source detection chain with positions from USNO catalogue · Remove gross offsets of central chip and then optimise outer CCDs displacement · Accuracy achieved (MOS1 and MOS2) RMS error of 0.5 arcsec Implemented in latest CCF file

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


Astrometry

Absolute Astrometry
(J. Tedds & M. Watson, SSC, poster WB1-7)

· Systematic correlation of source positions with USNO catalogue, based on the eposcorr SAS task, and a sample of about 150 source lists per camera · Frequency distributions FWHM are : 4" in RA, Dec, 0.3° in roll angle
XMM-Newton Instrumen t Calibration Workshop EPIC/MOS Cal. Status


PSF

Point Spread Function
(S. Ghizzardi & S. Molendi, poster WA2-4)

Have searched for an analytical representation of the PSF in azimuthal symmetry, with a large data set, up to 12 arcmin off-axis

King model found adequate for radial profile, with parameters : Rc and

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


PSF

PSF - Examples of fits

Fit takes into account a background component and rejects piled-up regions

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


PSF

PSF - Results
Core radius and slope are linear in energy and off-axis angle :
Rc(E, ) = a + b.E + c. + d.E. (, ) = x + y.E + z. + w.E.

Validity range of model identified :

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


PSF

PSF - Results relative to piled-up sources

Slight difference in encircled energy between MOS1 and MOS2 (e.g. here, ~ 0.03 for power laws and cut at 5 arcsec)

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


CTI

Charge Transfer Inefficiency
(P. Bennie et al., poster WA2-18) · CTI results in an apparent shift of lines and broadening · CTI has been very regularly monitored via the Al-K and Mn-K (1.5, 5.9 keV) lines from the onboard calibration source
Mn-K (peak ~ 1750)

Linear increase with additional steps related to large solar flares

Al-K (peak ~ 450)

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


CTI

CTI time and energy dependence

Note : not well reproduced by SAS v5.2, which underestimates the CTI (25 eV shift at Mn). New version in test for v5.3
XMM-Newton Instrumen t Calibration Workshop EPIC/MOS Cal. Status


CTI

CTI future
· Column to column variation of line centroid have been evidenced · EPIC looks into ways of including that in data treatment (CTI per column, deviation maps) · In any case, slight degradation of line resolution remains

Mn Line (adc)

Unrecoverable degradation : FWHM increase of ~ 4 eV / year w.r.t. start at ~ 130 eV

Days since launch XMM-Newton Instrumen t Calibration Workshop EPIC/MOS Cal. Status


RMF

Redistribution
(S. Sembay et al., poster WA2-5)

Redistribution @ 600 eV ground & flight

· Gaussian at high energy, with a strong shoulder at low energy (< 1 keV) · Very well measured on ground, but definitely not good for flight

· New version for E < 0.7 keV in prep. · Will be time dependent · Same function for all imaging modes

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


ARF

On axis effective area
(S. Sembay et al., poster WA2-5)

Telescope + RGA + filter + CCD

Residuals within 5 % from 0.2 to 10 keV

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


Background

Background
(2 posters WA2 : D. Lumb, and A. De Luca & S.Molendi, and an all EPIC work)

Background components : 1. 2. 3. 4. Low energy electronic noise Soft proton "flares" Quiet time high energy proton induced Astrophysical background

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


Background

Background - Soft protons

· Energy spectrum shape varying from flare to flare · For weak or diffuse sources only solution is to select quiet time periods

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


Background

Background - quiet time
· Induced by high energy particles : - directly in the CCD - indirectly via fluorescent lines

· Weakly variable with time · Hard spectrum with lines

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


Background

Background - quiet time - spatial variation

Spatial variability of : ~ 15 % for Al and Si K 10 % for E > 2 keV

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


Background

Background - new template files
· Selection of THIN filter, high galactic latitude, low proton background, low NH · Removal of bright sources · Duration now > 400 ks

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


General

Overall "first order" statements and to be done (I)
· Astrometry : "finished" · PSF : "Very good", high energy at large off-axis angles missing

· Vignetting : "Good" up to 10 arcmin, to be checked at larger angles · CTI degradation : "Within predictions", SAS to be updated · On axis effective area and redistribution good to 5 % 0.2-10 keV · Gain : good to 5 eV (relation with CTI ?) · Background : "Characterized" and template files built · Pile-up : "core exclusion" working - explore other alternatives
XMM-Newton Instrumen t Calibration Workshop EPIC/MOS Cal. Status


General

Overall "first order" statements and to be done (II)
· Lowest energies < 200 eV : variations not understood · Off-axis : - CCD QE from ground implemented above > 1 keV - known inhomogeneities below 300 eV not implemented yet - redistribution difficult to check - implement known thick filter inhomogeneities below C edge - analysis of extended sources has however not revealed any strong deviation from on axis response · Timing mode : timing aspect checked redistribution function to be worked out

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status


More

More to come and to read !
· Next talks on cross-calibration will show quality of fits and level of consistency within EPIC and between EPIC and RGS.

· Posters with all details are on display.

XMM-Newton Instrumen t Calibration Workshop

EPIC/MOS Cal. Status