A Search for Earth-size Planets

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KEPLER; Data Validation and Follow Up Observations

CoRoT SymposiumW.J. Borucki& the Kepler

Team 5 February 2009

A Search for Earth-size Planets

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Key

Ground Segment Roadmap

Functional Interface

Primary Command Flow

Primary Telemetry Flow

Project Scheduling

Services

Navigation (NAV)JPL

Deep Space Mission Systems

Mission Operations Center

LASP

Data Management CenterSTScI

Flight Planning CenterBATC

Science Operations Center

ARC

Stellar Classification

Program

Mission Management

OfficeARC

Science OfficeARC

Follow-up Observing Program

BATC LASP

ARCJPL

Sci TeamSTScI

A Search for Earth-size Planets

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Black level correction

Quarterly Processing

DMC

Ground-basedFollow up Observing

SOC Smear, flat field, dark current, nonlinearity, cosmic ray correction

OAP and DIA photometry to generate flux time

series

Pre-search data conditioning to remove

systematic errors

Transiting and reflected- light planet searchFocal Plane

Characterization

Data Validation

SOC data store

SOC Data Store

Photometer performance assessment

SOC data store

SOC Data Store

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Methods of Data ValidationUsing Kepler Data

• Rule out statistical fluctuations in the data, accept only signals that show 3 or more transits and that have a total signal-to-noise ratio that exceeds 7 sigma.

• To rule out small stellar companions of the target star, check for secondary eclipses and determine if the transit characteristics are appropriate for a planetary companion. Modeling effort will be used to distinguish stellar binaries from stars with planets.

• Check for background binaries that are in the target aperture; measure the movement of the image centroid before, during, and after the transit. This test is expected to rule out the hundreds of binary signals expected from background stars. The precision of the measurement depends on the stellar fluxes and positions but can be better than 0.01 pixel; i.e., 0.04”.

A Search for Earth-size Planets

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Ground-based Follow Upto Eliminate False-Positive Events

Those candidates that pass DV are examined using ground-based telescopes and radial velocity spectrometers.

1. Medium precision RV is used to rule out any remaining stellar companions.

2. High spatial resolution imaging is used to check for nearby stars that are in the aperture. (apertures depend on magnitude but are ~ 36 sq arc sec.)

3. If no confounding stars present, then the candidate observed with a large telescope such as Keck, HET, or Willilam Herschel for high precision observations to get the planet mass or an upper limit to it.

4. If there are some stars in the aperture, then the photometric observations are employed to look for the transit by one of the confounding stars. (Includes AO & HST observations for Earth-size candidates.)

5. If transit signal is not due to confounding stars, then the candidate is sent to a large telescope such as Keck, HET, or William Herschel for high precision observations to get the planet mass or an upper limit to it.

A Search for Earth-size Planets

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Coordination of Ground-basedFollow Up Observations

• Candidate Follow up

– Algorithm ranks several hundred candidates to set their priority

– Observers assemble to discuss & agree on targets

– Target information (RA, dec, mag, SpT, variability, ephemeris) sent to coordination website

• Coordination Web Site

– Organized by follow-up target and by observation request

– Contains all the information on the targets as requested by observers

– Contains intermediate results from observations and whatever compact, reduced data sets are required by the Follow up Observers Group

– Voluminous data is referenced by links to observers’ home facilities

• Coordination data base

– Operated by the Follow-up Coordinator to schedule and track status of observations requested by the PI and Science Team

• Results returned to Science Office• Science team meets to discuss results & make announcements

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DATA RELEASE POLICY

Figure 1. Relation between the times the data are returned from the spacecraft and when they are released.

Beginning of science operations (30 days after launch)

0

A ll data released

Data released:

End of nominal mission

Data produced:

1 yr

2 yrs

3 yrs

4 yrs

4.5 yrs

0

1 yr

2 yrs

3 yrs

3.5 yrs

All discoveries are released after the team meets to discuss the evidence and NASA HQ is informed.Pixel-level data and light curves are released with each discovery.