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The Ground Segment: Data Processing.

The Ground Segment: Data Processing. Software development in laboratories. Brazilian contribution. Michel Auvergne Réza Samadi (LESIA, Observatoire de Paris). An Overview of the Ground Segment. We will present in the following the content of the brown box. Telecommand generator.

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The Ground Segment: Data Processing.

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  1. The Ground Segment: Data Processing. Software development in laboratories. Brazilian contribution. Michel Auvergne Réza Samadi (LESIA, Observatoire de Paris)

  2. An Overview of the Ground Segment. We will present in the following the content of the brown box Telecommand generator Payload bench CorotSky Stellar Catalogues Raw Data archive C C C TC Structure Operationnal Software Orbit events Level 0 DB Quick Look Data pipeline Payload TM Calibration Calibration DB Corrections Antenna Alcantara Icones Network Vienna (?) Level 1 DB

  3. Operationnal Software What is an operationnal task : All tasks producing telecommand. The tasks to be fulfilled are: Determine the actual Line of Sight (quaternion). Identify for the two programs the targets. Define for the seismology channel the readout windowing. Attribute to each PF target an aperture (« Extracteur » device programming, see Vanderlei Parro’s talk) Define all the parameters needed by the on board software Verify that all work well before the beginning of observation.

  4. Seismology channel processing. At the beginning the ACS is controled by the Proteus StarTracker. To obtain the required pointing stability the ecartometric information coming from the instrument must replace the StarTracker. The first tasks are: Correct the full frame images of offset and background. Identify ~ 50 stars Determine the line of sight and the optical distortion. Identify targets to observe. Prepare the windowing.

  5. Stars identification. The tycho catalogue is used for Identification For each image the line of sight is computed by fitting.

  6. Prepare the readout windowing. Constraints on the windowing are verified. For instance: Readout time < 1 s. Binned background doesn’t share lines with stars windows.

  7. Planet Finding processing Prepare Image for Targets Identification

  8. Attribute aperture to PF targets Two steps: identify targets listed in the so-called exobasket. attribute an aperture giving the best S/N ratio there are 256 pre-defined templates for each CCD. They are optimized for bright stars (mv < 14.5) with spectral type F to K.

  9. Calibrations. • The calibrations will compute: • Gains of the 8 readout channels • Dark current over the orbit. • Protons flux variations over the orbit. • Effects of temperature on the photometric signal. • Compute the actual PSF. • (see the Leonardo da Silva‘s talk) Protons flux determined from MOST data

  10. Photometric Data Corrections. • The main corrections are: • Correct co-channel interferences • Offset subtraction • Gain correction (ADU -> electrons) • Integration time correction • Outliers suppression (e.g. cosmic rays) • Sky Background Characterization (see Eduardo Costa ’s talk) • Background subtraction • Depointing corrections (see Fabio Fialho’s talk) • They are applied in order to reach the requested performances in term of white noise and periodic noises.

  11. Offset correction (developped by Patrice Journoud, LESIA)

  12. Background correction (developped by Patrice Journoud, LESIA)

  13. Conclusions. The software described here will be delivered to CNES in april 2006. But after that date improvement could be introduced if necessary. The software will be update along all the mission, but with an activity peak during the first year after the launch.

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