 Myth: 3 sec memory  Reality: 3 years are passed  I’m not a goldfish, but…

 From PLATO-CAMTO-TS-90-LESIA  Dimension ed energy of Ghosts ▪ Extended and pointlike  Absent: requirements on scattered straylight ▪ Once there was a requirement: 20ph/pxl/s, but has been excluded (or forgot…), or my copy of the doc… ▪ Reduce to a PST/rejection requirement?  Requirements on transmission (to limit ‘blue’ light)  Requirements on cleanliness levels (not justified)

 It is the model of reference ZEMAX  Based on a slightly old design (some radii of curvature)  Structure is semiconceptual (tube & diaphgrams) 90% absorbing, 10% lambertian scattering  All lenses and window (front face included) have 1% AR coating  20A microroughness and CL500 dust on window  The CCD has a 1-QE reflectivity  Fed by a 240mm diam circular collimated source of 4W (1W on the entrance pupil), moved along the diagonal of FoV  Wavelength weighted to reproduce energy of a G0

 TOU-OPT28: Should a ghost image be focused on the detector, its relative intensity shall be less than 0.2% (TBC) of the flux of the star which creates the ghost.  Due to the presence the flat window  Using Rlenses=1%, Rccd=1-QE Deltam~6

 TOU-OPT27: The surface of ghost light beams at the detector surface shall be greater than 3000 pixels (TBC) Column Min

Up to mNstarsUp to mNstarsUp to mNstarsUp to mNstars E E E E E E E E E E E E E E E+08 Based on Allen (1973) m<10 Bahcall&Soneira m>10 Spectrum: G0 Number of stars in Plato TOU field up to the m mag

 Build a Ghost Simulator form several (105) zemax files and IDL routines.  Used in two ways  Single source: to extract data of ghosts: positions, radius and percentage of rays entering the pupil that can form the ghost  Multi source: using the previous stellar model, to simulate an entire field

MagStar Extended Ghosts Point-like ghosts Average due to extended ghostsVariance E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E-04 TOTAL3.96E E E E-01 Brightes features are present from the beginning Adding higher mags adds an offset Evolution of extended ghosts with mag

Inside FoV is 2-2.5% (was 1% without CCD reflection) Outside FoV is similar to old 6 lenses or better because the tube is larger and exactly the same of that of ‘6 lenses’ Stars + Zodiacal light

 3 ‘families’ and 5 models  1-4,2-3 (N), 5(F)  Composed by two part  interface ring: ▪ identical for all models, ▪ is the interface with the TOU tube ▪ ‘hosts’ the window  Cone: ▪ different cut angle and height according to family ▪ Different orientations according to model TypeCut Angle Rotation angle H N exemplars (92)? (92)?

 Not for “direct” stray light from astronomical objects (they are too small)  Thermal?  On a ‘prudence basis’ to ‘fight’ TOU mutual scattering and satellite (sunshield) scattering  At the moment we don’t have any simulation to support that ▪ Simulations are difficult because ▪ We need information about all the system (disposition of TOUs, materials, sunshield…) ▪ The system is big but the single TOU pupil is small: raytracing may have poor statistic

 Requirements (from system?)  Model  Migration to ASAP  Optical design  Mechanical design  Coatings  Sources  Check calculations ph/s/pxl  Earth /Moon  Satellite / Mutual scattering