Instrument performances.

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M. Auvergne. Natal October 2004

Instrument performances.

•Signal perturbations:Radiations.Scattered light.ACS.Temperature.Readout electronic.

•Calibrations and ground based corrections.

•Performances on the two channels. Based on lab calibrationsand simulations with the instrument model

Michel Auvergne: Instrument scientist

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Aperture photometry

PF CCD image and apertures of selected targets

PF channel: for each target an optimalaperture (best S/N) is chosen among256 predefined apertures.

AS channel: an optimal apertureis computed for each target.

AS target image and aperture. QuickTime™ et un

décompresseur TIFF (LZW)sont requis pour visionner cette image.

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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 ~ 0-3PF ~ 10

See Leonardo talk

Protons flux (AP8 min) function of time

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Scattered Light from the earth

Depends on the Line Of Sight (LOS)

For a LOS orthogonal to the orbit planethe SL is ≤ 1 e-/px/sec and reach100 e-/px/sec for a depointing of 12 degrees

Variations of the maximum SL level on 150 days for several LOS.

The background is measured on board on the two channels.200 background windows on the PF channel.10 background windows on the AS channel.

QuickTime™ et undécompresseur TIFF (LZW)

sont requis pour visionner cette image.

Background light curve.Ordinate unit e-/px/sec.

SL

Zodiacal light

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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 theI/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

PF: Frontiers effect on colored photometry

AS: side effect due to image jitterJitter~0.06 px



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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 stabilizedat -40 C with white fluctuations of 0.005 C.

The orbital amplitude of readout electronicsis less than 0.3 K

Orbital temperature variations of the readout electronic

Annual amplitude variations of the readout electronic

Total amplitude in the light curve.Porb -> A< 20 ppm Harmonics < 2 ppm

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Calibrations.

Corrections are based on ground-based (CCDs), and on-board calibrations and Housekeeping (temperatures and voltages).•Ground based calibrations. CCDs Temperature sensitivity

PRNUGainFull Well capacityTraps and bright pixels.Polarisation voltagesLinearityDark current (before and after irradiation)

Readout electronicsTemperature sensitivityGainReadout noiseLinearity

•On-board calibrations will be used also to define parametrization of the flight software (see Leonardo’s talk). Full well capacity map



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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 madeon board.

On the PF channel, the background is measuredin 10*10 pixels windows. Substraction is made onground.The measurement precision is 5%.The residual noise is the background photon noise.



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Corrections: ACS Jitter.

On the AS channel the jitter effectis very small. The periodic componentscan be reduced by a factor 2.

On the PF channel the frontiers effectsare efficiently reduced.

More details in Fabio’s talk.

Blue: light curve with jitter fluctuations only.Black: light curve after correction.

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ordinate adu/exposure

Raw AS light curves.

AS: raw light curve for a 6 mag. StarBackground corrections are made on board QuickTime™ et un

décompresseur TIFF (LZW)sont requis pour visionner cette image.

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PF Light curve

PF white light curve with background removed. Missing data are due to the SAA crossing. Ordinate adu/exposure.



PF raw light curves for a 14 mag. starBlue curve: blue LCRed curve: red LCGreen curve:green LCBlack curve: background

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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 gradientsTools for statistical analysis of the signal.

Claudia Angeli (post-doc)Tools for statistical analysis of the signal.MMI, tbc

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Estimated White noise budget error:

0

2

4

6

8

5 6 7 8 9 10 11

White noise on 5 days

Photons noise (ppm on 5 days)

mv

Red: total noiseBlue: photons noise

0

0,0002

0,0004

0,0006

0,0008

0,001

0,0012

10 11 12 13 14 15 16 17

Noise for 1h integration

photon noise PF 1h

mv

Dominant noise: readout Dominant noise: jitter+readout+background

Asteroseismology Planet Finding

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Global Budget error.

AS White noise 5 d. Orbital components

Comment

mv = 6.

Teff = 6250.

0.62 N0: 20, 12 10, 6

N1: 6,4,3,2

H1: corrections reduce amplitude

by a factor 3

PF White noise 1h Orbital components

mv=14

Sp. Type: K

2.2E-4 N0: 120 ppm

N1: 60 ppm

H1: corrections reduce amplitude

by a factor 2.

mv = 15.5

Sp. Type: K

7.4E-4 120 ppm

Instrument performances.

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