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Instrument performances.

Instrument performances. Michel Auvergne: Instrument scientist. Signal perturbations: Radiations. Scattered light. ACS. Temperature. Readout electronic. Calibrations and ground based corrections. Performances on the two channels. Based on lab calibrations

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Instrument performances.

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  1. Instrument performances. Michel Auvergne: Instrument scientist • Signal perturbations: • Radiations. • Scattered light. • ACS. • Temperature. • Readout electronic. • Calibrations and ground • based corrections. • Performances on the • two channels. • Based on lab calibrations • and simulations with the instrument model

  2. Aperture photometry PF channel: for each target an optimal aperture (best S/N) is chosen among 256 predefined apertures. AS channel: an optimal aperture is computed for each target. PF CCD image and apertures of selected targets AS target image and aperture.

  3. Radiations. Depends on the shielding which is thicker than 10 mm in most directions. With 10 mm aluminium no e-, only p+ Ep > 50 MeV. Perturbations inside the SAA. Time spent in the SAA ~ 4% Max flux ~ 4000 p+/cm2/sec. Number of charges in an impact ~ 6000 e- Data acquisition interrupted on the planet finding channel for flux larger than 300 p+/cm2/sec Number of glitches in an aperture during an exposure in the SAA. AS ~ 0-3 PF ~ 10 See Leonardo talk Protons flux (AP8 min) function of time

  4. Scattered Light from the earth Depends on the Line Of Sight (LOS) For a LOS orthogonal to the orbit plane the SL is ≤ 1 e-/px/sec and reach 100 e-/px/sec for a depointing of 12 degrees The background is measured on board on the two channels. 200 background windows on the PF channel. 10 background windows on the AS channel. Variations of the maximum SL level on 150 days for several LOS. SL Background light curve. Ordinate unit e-/px/sec. Zodiacal light

  5. Attitude Control System. Four orbital components (orbit period and harmonics), due to gravity torque and magnetic field, plus a random component. The main photometric effect comes from the I/O of the image from the aperture (side effect) for AS and from frontiers effect on PF channel. Spectrum of the x component of the ACS jitter AS: side effect due to image jitter Jitter~0.06 px PF: Frontiers effect on colored photometry

  6. Temperature. Photometric variations comes from: Quantum efficiency (100-500 ppm/K) Readout Gain (20 ppm/K) Readout Offset (500 ppm/K) The offset is measured on board. The CCDs temperature is stabilized at -40 C with white fluctuations of 0.005 C. The orbital amplitude of readout electronics is less than 0.3 K Orbital temperature variations of the readout electronic Total amplitude in the light curve. Porb -> A< 20 ppm Harmonics < 2 ppm Annual amplitude variations of the readout electronic

  7. Calibrations. • Corrections are based on ground-based (CCDs), • and on-board calibrations and Housekeeping • (temperatures and voltages). • Ground based calibrations. • CCDs Temperature sensitivity • PRNU • Gain • Full Well capacity • Traps and bright pixels. • Polarisation voltages • Linearity • Dark current (before and after irradiation) • Readout electronics • Temperature sensitivity • Gain • Readout noise • Linearity • On-board calibrations will be used also to define • parametrization of the flight software (see Leonardo’s talk). Full well capacity map

  8. Corrections: Scattered light On the AS channel,the background is measured in 50*50 pixels windows close to the target, with a binning of 5*5 pixels. Substraction is made on board. On the PF channel, the background is measured in 10*10 pixels windows. Substraction is made on ground. The measurement precision is 5%. The residual noise is the background photon noise.

  9. Corrections: ACS Jitter. On the AS channel the jitter effect is very small. The periodic components can be reduced by a factor 2. On the PF channel the frontiers effects are efficiently reduced. More details in Fabio’s talk. Blue: light curve with jitter fluctuations only. Black: light curve after correction.

  10. Raw AS light curves. AS: raw light curve for a 6 mag. Star Background corrections are made on board ordinate adu/exposure

  11. PF Light curve PF raw light curves for a 14 mag. star Blue curve: blue LC Red curve: red LC Green curve:green LC Black curve: background PF white light curve with background removed. Missing data are due to the SAA crossing. Ordinate adu/exposure.

  12. Brazilian contribution. Leonardo Pinheiro da Silva (thesis) Calibrations processing. (See following talk) Fabio de Oliveira Fialho (thesis) Aperture definition and ACS corrections.(See following talk) Eduardo Costa da Silva (post-doc) Photometric corrections, in particular background gradients Tools for statistical analysis of the signal. Claudia Angeli (post-doc) Tools for statistical analysis of the signal. MMI, tbc

  13. Estimated White noise budget error: Asteroseismology Planet Finding Dominant noise: jitter+readout+background Dominant noise: readout

  14. Global Budget error.

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