Beyond TAOS: Future Blind Field Surveys Charles Alcock University of Pennsylvania With major...
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Transcript of Beyond TAOS: Future Blind Field Surveys Charles Alcock University of Pennsylvania With major...
Beyond TAOS: Future Blind Field Surveys
Beyond TAOS: Future Blind Field Surveys
Charles AlcockUniversity of PennsylvaniaWith major contributions from
The TAOS Science Team &
Ball Aerospace
Charles AlcockUniversity of PennsylvaniaWith major contributions from
The TAOS Science Team &
Ball Aerospace
Plan of the talk:
• The scientific need for an occultation survey that is more capable than TAOS
• Description of occultations by TNO’s– What TAOS will do– What TAOS will not be able to do
• Beyond TAOS: – An expanded ground-based array– A space-based survey
The Scientific Needs (beyond TAOS):
• Census of TNO’s with size < 1 km to study the collisionally eroded regime
• Better estimates of sizes• Shape determination• Distance estimates are critical!• Ultimate goal should be to survey the entire
Solar System – out to the Oort Cloud!
Next Generation TAOS: an expanded ground-based array
• Larger telescopes for more stars at greater S/N (1 meter class with field of view > 1.5o)
• More telescopes (~10) spread out over several kilometers to sample the diffraction patterns– Distance estimates become possible– Sample smaller objects
Multiple telescopes are useful
• Help to control false positives (critical in TAOS)• A spatially expanded array can sample the
shadow pattern (shape & distance information)– Spacing ~1 km North-South– Spacing >10 km East-West (may need to move
telescopes seasonally)– Real estate problem (Atacama plateau?)!
Site selection not straightforward:
• Dark sky, good seeing for photometric precision
• Accommodate array kilometers across• Possible need to move telescopes seasonally
– Western US– Northern Chile
Need to operate faster than 5 Hz:
• Use “frame-buffer” CCDs– Increase sampling rate (~10 Hz)– Eliminate streaking characteristic of zipper
mode– Scalable to large focal planes
• May upgrade TAOS using this architecture (TAOS II)
Beyond TAOS: a space-based system similar to Kepler
• S/N > 10 on ~150,000 stars at 30 Hz
• Potential to survey down to ~100 meters
• Reliable statistical estimates of distances
• Crude shape estimates• Thousands of events• Oort Cloud …?
“Straw man” design based upon Kepler
• Kepler will follow 160,000 stars in one field to search for planetary transits
• Aperture 95 cm
• Schmidt design gives wide field of view (8o)
• Photometric samples taken every 2.5 seconds– Co-added into 15 minute bins to give very high
precision photometry
“Straw man” design based upon Kepler
• Occultation mission similar, but:– Add small angle prism to corrector lens to give
modest spectral dispersion– Sample frequently (nominally 30 Hz)– Lower S/N ~ 10 is acceptable– Extremely high data rate – Multiple pointings along and near the invariable
plane
10:23:38
KEPLER Telescope Scale: 0.06Positions: 1-5
06-Aug-03
403.23 MM
Add small angle prism to corrector lens to give modest spectral dispersion
The focal plane and data path are very challenging:
• 50-100 million imaging pixels
• Each star spectrally dispersed over 5-10 pixels
• Sample at ~30 Hz
• Need substantial pre-processing on board