CCD OVERVIEW

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CCD OVERVIEW

• Kepler will have 42 CCDs
• 2,200 column x 1,024 row full frame CCDs
• Field of View (FOV) gt 100 square degrees (113 w/
  vignetting)

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DATA SOLAR SYSTEM

• A great deal of information, But

• Single example.
• Biased example We are here!

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KEPLER and The Planet Finder (TPF)

• Excerpts from the National Research Council
  (NRC) report with regard to TPF
• . TPF will revolutionize major areas of
  planetary and non-planetary science
• ...it is important to determine prior to the
  start of the mission that it is likely that there
  will be an adequate number of Earth-sized planets
  for TPF to study." (p. 112)

National Research Council
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MORE PLANETARY SCIENCE

• Terrestrial planet multiplicity.
• Terrestrial planet coplanarity ( 12 chance of
  seeing both Venus Earth if either is seen).
• Single transits of 30 cold Jupiters (SNR 400).

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TRANSIT

• Transit observation by HST of a jovian-size
  planet orbiting hd209458

Ten-minute to ten-minute binned data from several
orbits have a precision of 60 ppm (Brown et al.
2001).
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BINARY SEPARATION
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MAIN SEQUENCE STARS
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PLANETS PER DURATION
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KEPLER SPACECRAFT
Sunshade
Photometer
Radiator
Solar Array
Spacecraft
High gain Antenna
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DETECTION CAPABILITIES
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TRANSIT PROPERTIES
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EXPECTED TRANSITS

• EXPECTED NUMBER OF GRAZING TRANSITS BY TARGET
  STARS
• 50 of target stars are binaries gt 50,000
  targets are binaries
• 20 have orbital periods of order days to weeks
• 10,000 stars with transit probabilities near 10
• 1000 stars will show stellar transits
• Of these 1,000 stars,
• 6.5 (i.e., 65) stars will show 1 deep
  transits
• 1.4 (i.e., 14) stars will show 0.1 deep
  transits
• 0.3 (i.e., 3) stars will show 0.01 deep
  transits
• 20 have orbital periods between a few months and
  a few years
• 10,000 stars with transit probabilities near 1
• 100 stars will show stellar transits
• Of these 100 stars
• 6.5 (i.e., 6 ) stars will show 1 deep
  transits
• 1.4 (i.e., 1.4 ) stars will show 0.1 deep
  transits
• 0.3 (i.e., 0.3 ) stars will show 0.01 deep
  transits

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REQUIRED SENSITIVITY

• ?L/L area Earth/area Sun 1/12,000 8x10-5
• Require total noise to be lt2x10-5 for 4-sigma
  detection in 5 hours
• Three sources of noise and their contributions
• - Stellar variabilitylt1x10-5, typically for the
  Sun on timescale of 1/2 day
• - Shot noise1.4x10-5, in 5 hr for mv12
  solar-like star and 1-meter aperture
• - Instrument noise lt1x10-5, including detector
  dark current, electronics read noise, thermal
  effects, spacecraft pointing jitter, and
  shutterless operation.
• Detector of choice array of 422kx1k CCDs with
  27µm pixels and dual readout
• - Both SITe and EEV are thinned,
  back-illuminated, delta-doped, AR coated
• Limiting bright magnitude of mv9 and full-well
  depth of 825 e-/µm2 requires
• - Defocus image to 5 pixel diameter and readout
  every 3 seconds.

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MEASUREMENT TECHNIQUE

• Use differential photometry (common mode
  rejection)
• - Brightness of each star is re-normalized to the
  ensemble of thousands of stars in each quadrant
  of each CCD, readout with a single amplifier
• Transits only last several hours
• - Long term photometric stability not necessary
• Defocus the star image to five pixel diameter
• - Mitigates saturation (109 e-/hr) and
  sensitivity to motion
• Control pointing to 28 millipixels (0.1 arc sec)
  
• - Star images remain on the same group of pixels,
  eliminates effects of inter-pixel variations in
  sensitivity
• Operate CCDs near full-well capacity
• - Dark current and read-noise effects become
  negligible
• Place the photometer in a heliocentric orbit
  (SIRTF-like)
• - Provides for a very stable thermal and stray
  light environment.

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ORGANIZATION
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SINGLE TRANSIT SNRS

• Approximate Single Transit SNR's for a 12th mag
  Star

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DETECTABLE SIZE
Detectable planet size vs. Orbital semi-major
axis and star mass

• Each plot is for a given stellar brightness.
  Planets of a given size are detectable to the
  left of each contour. Detection are based on a
  total SNRgt 8 s and gt 3 transits in 4 years.

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DETECTABLE STARS
Number of stars that can be detected vs planet
size as a function of stellar type
The solid lines show the number of dwarf stars of
each spectral type for which a planet of a given
radius can be detected at 8s. These numbers are
based on 4 near-grazing transits with a 1-yr
period and stars with mv lt 14. The dashed lines
show a significant increase in the number of
stars when assuming 4 near-central transits .
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SNR

• SNR as a Function of Transit Duration and Stellar
  Variability

The three curves give the SNR for 4 combined
transits about an mv12 solar-like star at times
of low, medium, and high stellar variability.
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DETECTABLE RADIUS
Effect of Stellar Variability on Detectable
Planetary Radius
Earth-sized transits are readily detectable for
stars with variability comparable to that of the
Sun.
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Test bed BRIGHT STAR EFFECT

• Within the planned Kepler Mission field-of-view
  there are several stars as bright as mv4. To
  simulate the impact of a bright star in the
  field, fiber optics were used to generate mv4
  stars at various distances from stars in the
  field. The effect of a bright star does not raise
  the general system noise above the red line noise
  limit. Only the nearest star within a few CCD
  columns of the mv4 star was significantly
  affected. Both its noise and apparent brightness
  increase.

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Test bed S/C MOTION EFFECT

• In this 46 hour test the camera was moved at
  various amplitudes and rates characteristic of
  the spacecraft guidance system performance. The
  jitter model used predicted a 1s standard
  deviation in pointing of 0.01 arcsec in each
  axis, corresponding to 2.8 millipixels on the
  CCD. Deviations were typically less than 4s
  during the test, i.e., 11 millipixels.
• The test results show that the system noise is
  still below the maximum allowable noise except
  for a small number of deviant stars.

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SUMMARY

• The Kepler Mission is designed to detect hundreds
  of Earth-size planets by looking for transits. To
  demonstrate the technology to be utilized, a
  Testbed Facility has been built and operated with
  a flight type CCD. The facility simulates all of
  the features of the sky and the
  spacecraft/instrument that are important for the
  success of the mission.
• Optimum operating conditions for defocus,
  photometric aperture size vs stellar brightness
  and maximum operating temperature have been
  measured.
• The required photometric precision has been
  demonstrated while operating without a shutter
  during readout, having some saturated pixels in
  the brightest stars, working in a crowded field
  with a star density the same as planned for the
  mission, inclusion of spacecraft jitter, and over
  a dynamic range of five stellar magnitudes.
• Tests of comic-ray hits and field rotation (which
  occurs every three months during the mission)
  also do not appear to have detrimental affects.
• Transits have been injected and detected at the
  required statistical significance under all
  operating conditions during all tests.
• The Kepler Mission is ready for flight status.

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SPECTRAL TYPE
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TRANSITS OBSERVED BY VULCAN
HD 209458
Cygnus 3047
Cygnus 3047
Cygnus 937
Perseus 0831
Cygnus 1433
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DETECTION RATE

• Expected detection rate for hot Jupiters
• Probability that

• the target star is dwarf 0.5
• the star is single or a widely space binary 0.5
  to 0.8
• the star has a hot Jupiter 0.01 to 0.02
• the orbital plane is correctly aligned 0.1
• six weeks of data show at least three transits
  0.6
• Product of the probabilities 1.5 to 4.8 x10-4
• Yield Product of probabilities times number of
  stars monitored 1.5x10-4 x 104 stars 1.5 to 5
  planets

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VULCAN
Vulcan transit search of 6,000 stars for
extrasolar planets

• OBJECTIVES
• Monitor 6000 stars continuously for periods of
  at least 6 weeks
• Detect jovian-size planets in short period orbits
• Use Doppler-velocity measurements to determine
  mass and density
• TELESCOPE
• Aperture 10 cm
• Focal length 30 cm
• Field of View 7x 7 degrees
• Detector 4096x4096 CCD with 9 m pixels