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Workshop

First look, calibrations, reference sources

IAP – 24 November 2005

1. CU6 structure

2. Aims of the workshop / open questions

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CU6 structure

DU1000 Management of the coordination unitDU2000 Database & data analysis architecture

DU3000 Spectra extraction & background modellingDU4000 Data sanity check & quick calibrationsDU5000 Nominal calibrationsDU6000 Meta-processing

DU7000 Single stars radial & rotational velocitiesDU8000 Multiple stars radial & rotational velocitiesDU9000 Stability/variability assessment

“CU6 spectroscopic processing development plan”(Version 1: December 2005)

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Example of WBS: DU6000 Meta-processing

• WP6100 Management of DU6000.• WP6200 Apply calibrations.• WP6300 Clean spectrum. (or in background modelling)

– WP6310 Filter defective pixels.– WP6320 Filter optical defects (ghosts, …).– WP6320 Filter cosmic rays.

• WP6400 Normalize to continuum.• WP6500 Combine observations.

– WP6510 Examine/use astrometric and photometric information.– WP6520 Examine/use evolution of spectral morphology.– WP6530 Examine/use radial and rotational velocities information.– WP6540 Use available information and optimally combine spectra.

• WP6600 Spectra transforms– WP6610 Fourier transforms.– WP6620 Wavelet transforms.

• WP6700 Filter noise– WP6710 Overview of existing techniques.– WP6720 Filter noise in Fourier space.– WP6730 Filter noise in wavelet space.

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Example of WBS: DU7000 Single star radial & rotational velocities

• WP7100 Management of DU7000.• WP7200 Auxiliary data: general.

– WP7210 Define & summarize needs and build test data set.– WP7220 Define and summarize needs for template spectra.– WP7230 Manufacture masks.– WP7240 Define/build library of rotational velocity standard– WP7250 Implement auxiliary data access methods.

• WP7300 Auxiliary data: radial velocity standard.– WP7310 Define list of potential calibration stars.– WP7315 Observe potential calibration stars.– WP7320 Derive RV of potential calibration stars.– WP7325 Identify stable stars.– WP7330 Assess RV shift due to instrum./wavel. range/techniques.– WP7360 Define list of potential calibration asteroids– WP7365 Simulate the observation of potential calibration asteroids– WP7370 Assess consistency asteroid/star for RV zero point.– WP7375 Observe asteroids.– WP7380 Assess performance with observed asteroids.

• WP7400 Radial velocity derivation methods (including error assess.).– WP7410 Overview of existing techniques.– WP7420 Cross-correlation in data space with template.– WP7430 Cross-correlation in data space with mask.– WP7440 Cross-correlation in Fourier space.– WP7450 Minimum distance method.

• WP7500 Rotational velocity derivation methods (including error assess.).– WP7510 Overview of existing techniques.– WP7520 Width of correlation peak.– WP7530 Fourier transforms.– WP7540 Minimum distance method.– WP7550 Neural network.

• WP7600 Identification/correction of outliers.– WP7610 Overview of existing techniques.– WP7620 Boot strap.

• WP7700 Comparison of method performance.– WP7710 Define comparison criteria.– WP7720 Compare methods and synthesize results.

• WP7800 Assessment of radial velocity astrophysical zero point.– WP7810 Review and define effects that should be taken into account.– WP7820 RVS to solar system barycentre reference frame transform (under CU3 responsibility?).– WP7830 Gravitational redshift.

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Aims of the workshop

• Discuss the 3 related issues of First look, calibrations and reference sources→ direct discussion/brainstorm: questions, present different approaches & different points of view

• Address / answer some specific question

• Try to define an high-level overall approach for first look / calibration: i.e. baseline scenario (that will be iterated/modified).

• Define methodology to refine WBS

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First look• Tasks of first look?

– Check good health of the instrument?– Check good health of the spectra? Which spectra? How many spectra?– Perform quick calibrations? Use the nominal calibration algorithms with

different input data?– Check scientific performance?– ...?

• Frequency? Daily basis? Monthly basis (weakest spectra)?• Methods?• Auxiliary data? Dedicated observing program(s)?

V Types Nph /samp G2V Nph /samp (/spe) K1III Nspectra / day

18 All 0.7 1 (3 300) 12.5 106

15 All 10 15 (52 000) 1.2 106

14 All 25 45 (130 000) 500 000

13 All 70 110 250 000

12 All 175 285 100 000

12 F-G-K 175 285 75 000

12 F-G-K No-crowd 175 285 37 500

10 F8-G-K - stable 1125 1795 2 500

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Nominal calibrations

• Which instrumental quantities should be calibrated? How?

• How frequently should the nominal calibrations be performed? weekly? monthly? Why? Is there a gain in continuity over several days/weeks? Are there long-term effects to calibrate (e.g. over one precession period? e.g. over one year?)?

• Volume/type of calibration data?

• Auxiliary data? Dedicated observing program(s)?

• Is the “global iterative approach” appropriate for all calibrations?

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Reference sources

• Type of standards? Qualified before/during the mission, by us/by others.

• How to identify standards? How to qualify standards? How to achieve absolute RV at the 300 m/s level? Are some software developments required?

• How many standard will we qualify? How many will others qualify?

• How to test the performance of RV standard for SGIS?

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Agenda

10:00 – 10:40 Introduction10:40 – 11:30 Overview of first look11:30 – 12:20 Overview of the calibrations12:20 – 13:00 An example: wavelength calibration

13:00 – 14:10 Lunch

14:10 – 15:00 Radial velocity reference sources15:00 – 16:30 Synthesis discussions