Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Amon Presentation: 23 April 2002Page 1 XMM-Newton In-Orbit vignetting calibration of the XMM-Newton telescopes Marcus G. F. Kirsch, D.H. Lumb, A. Finoguenov, R. Saxton, B. Aschenbach, P. Gondoin, I. Stewart

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 2 XMM-Newton EPIC XMM-Newton Mirrors 3 Wolter Telescopes, with 58 concentric mirror shells each focal length: 7.5 m angular resolution: 6 arcseconds (FWHM ) point-spread function: 15 arcsec (HEW)

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 3 XMM-Newton EPIC VIGNETTING VIGNETTING – the reduction in effective area with off-axis angle important for: –cluster surface brightness –counts:flux conversions in population study –background normalisation on-ground the X-ray measurements in Panter were in diverging beam and/or the grating stacks and stray light baffle were installed in parallel UV beam no measurement of energy dependence need to confirm the alignments survived thermal relaxation of optical bench, launch, and AIV campaigns measure energy dependence in orbit D. Lumb

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 4 XMM-Newton EPIC typical Vignetting result compare vignetting with data in telescope calibration files unexpected variations (~10%) in rel. vignetting with azimuth in PN attributed initially to problems in BG correction and/or exposure time correction but relative variations are correlated with camera orientation possible misalignment of the telescope axis compared with nominal reference pn, 11 arcmin from nominal boresight

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 5 XMM-Newton EPIC modifying telescope axis on –ground data had been inconsistent to ~30 arcsec typically mirror alignment cube either blocked or possibly moved during AIV ? for each telescope could minimise discrepancies in measured vignetting by positing a telescope axis shift of up to 1 arcmin try to find sensitive method to determine the shift

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 6 XMM-Newton EPIC the 4 methods source at different position diffuse background source elongation coma cluster

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 7 XMM-Newton EPIC 3C58 and G M. Kirsch D. Lumb

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 8 XMM-Newton EPIC vignetting: the shift MOS2 G (stars) & 3C58 (squares) pn center at DETX=340 DETY=1300 D.H. Lumb

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 9 XMM-Newton EPIC diffuse background high galactic latitude background data sets compiled for cluster studies removal of most sources, and co-addition of different fields leaves a very uniform surface brightness which should track the vignetting modified by the particle background – has different vignetting function (cosmic rays flat, soft protons scatter down mirror system) D.H. Lumb

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 10 XMM-Newton EPIC source elongation With increasing off-axis angles sources become elongated (in direction tangential to their radius vector) Plot elongation vs. angle to define centroid via mirror geometric properties R. Saxton

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 11 XMM-Newton EPIC Coma cluster a repeat observation of the cluster centre was made at new position angle comparing surface brightness in same sky region reveals under- or over-correction (dotted line) adjust the centroid of vignetting function to minimise these differences (solid line) A. Finoguenov

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 12 XMM-Newton EPIC position of optical axis detector co-ordinates (0.05 arcsec)

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 13 XMM-Newton EPIC position of optical axis currently under testing in DT SAS

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 14 XMM-Newton EPIC calculate new BS angles the new optical axis position required a set of new Boresight CCFs which hold for each instrument a triple of three angles describing the misalignment of the respective instrument boresight with respect to the satellite coordinate frame using the OMC2/3 field new BS misalignment angles for all the three cameras have been calculated goal: astrometry should not change!!!!!!!!!

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 15 XMM-Newton EPIC astrometry: EPIC-2MASS RA offset: arcsec DEC offset: arcsec RA offset: arcsec DEC offset: arcsec RA offset: arcsec DEC offset: arcsec RA offset: arcsec DEC offset: arcsec RA offset: arcsec DEC offset: arcsec RA offset: arcsec DEC offset: arcsec B. Altieri old optical axis and BS: new optical axis and BS

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 16 XMM-Newton EPIC 3C58 results for MOSs Model: constant[1]*wabs[2]( powerlaw[3] ) ? flux variation off axis reduced from ± 10 % down to ± 1-2 % for both MOSs pn to be checked with Coma/G observations M. Kirsch

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 17 XMM-Newton EPIC missing/finding the gap in order to recover properly the flux sources should not fall onto CCD gaps also the condition of the right off axis angle must be taken into account 8 observations have been optimised for that ....one not enough

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 18 XMM-Newton EPIC absolute timing accuracy news in Timing accuracy and capabilities of XMM-Newton in Proc. SPIE 5165 Timing accuracy and capabilities of XMM-Newton M. G. F. Kirsch 1), W. Becker 5), S. Benlloch-Garcia 4), F. A. Jansen 2), E. Kendziorra 4), M. Kuster 5), U. Lammers 2), A. M. T. Pollock 1), F. Possanzini 3), E. Serpell 3), A.Talavera 1)

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 19 XMM-Newton EPIC EPIC-pn quadrant clocks UTC OBT 100  s 50  s 30  s orbit prediction 20  s XMCS  s th. absolute accuracy theoretical upper limit for absolute time uncertainties is <100 s the limited number of analyses conducted so far indicated in the past that the actual error is larger (~1ms)

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 20 XMM-Newton EPIC a. accuracy: the bug wrongly corrected CDMU delay ( s) delay was erroneously subtracted instead of added --> shift of s. --> shift of s. correction will be implemented in new time correlation work around will be issued on XMM-Newton-SOC pages UTC(OBT) = ERT +  (CDMU) -  (Flight) -  (G/S) (for details see Kirsch et al. Proc. SPIE 5165)

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 21 XMM-Newton EPIC absolute timing with the Crab absolute timing accuracy: ~ s absolute timing accuracy: ~ s in agreement with Crab observations performed by RXTE and Chandra opportunity to contemporaneously observe the Crab with Chandra and in the optical using an MPE developed fast photometer to get a radio-ephemeris independent phase solution between the optical and X-ray pulses in REV: NRCO scheduled Rev T04:17:05 (for details see Kirsch et al. Proc. SPIE 5165)

Marcus Kirsch Science Operations & Data Systems Division Research & Scientific Support Department Page 22 XMM-Newton EPIC EPIC data anomalies  pn-AUX data anomalies : – –frequency of occurrence is varying – –unrelated to camera mode, observing time and/or duration –random negative or positive jumps in FTCOARSE not found occasionally by SAS pulse peak broadening, phase shift spurious pulse components SAS 6.0 (winter 2003 ? ): refined detection/correction algorithm --> all problems will reliably found and corrected W. Becker M. Kirsch (for details see Kirsch et al. Proc. SPIE 5165)