[meteorite-list] Sharpest-ever Ground-based Images of Pluto and Charon: Proves a Powerful Tool for Exoplanet Discoveries

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 27 Sep 2012 17:25:48 -0700 (PDT)
Message-ID: <201209280025.q8S0PmFS011327_at_zagami.jpl.nasa.gov>

http://www.gemini.edu/node/11893

Sharpest-ever Ground-based Images of Pluto and Charon: Proves a
Powerful Tool for Exoplanet Discoveries

Gemini Observatory Press Release
    
For immediate release on September 26, 2012

Science Contacts:

      Steven Howell
      NASA Ames Research Center
      Moffett Field, CA
      Desk: 605-604-4238
      Cell: 520-461-6925
      Steve.b.howell"at"nasa.gov <mailto:Steve.b.howell at nasa.gov>

      Elliott Horch
      Southern Connecticut State University
      New Haven, CT
      Phone: 203-392-6393
      Horche2"at"southernct.edu <mailto:Horche2 at southernct.edu>


      Media Contact:

      Peter Michaud
      Public Information and Outreach Manager
      Gemini Observatory, Hilo, Hawai'i
      Desk: (808) 974-2510
      Cell: (808) 936-6643
      pmichaud"at"gemini.edu <mailto:pmichaud%20_at_%20gemini.edu>

Despite being infamously demoted from its status as a major planet,
Pluto (and its largest companion Charon) recently posed as a surrogate
extrasolar planetary system to help astronomers produce exceptionally
high-resolution images with the Gemini North 8-meter telescope. Using a
method called reconstructive speckle imaging, the researchers took the
sharpest ground-based snapshots ever obtained of Pluto and Charon in
visible light, which hint at the exoplanet verification power of a large
state-of-the-art telescope when combined with speckle imaging
techniques. The data also verified and refined previous orbital
characteristics for Pluto and Charon while revealing the pair's precise
diameters.

"The Pluto-Charon result is of timely interest to those of us wanting to
understand the orbital dynamics of this pair for the 2015 encounter by
NASA's New Horizons spacecraft," said Steve Howell of the NASA Ames
Research Center, who led the study. In addition, Howell notes that
NASA's Kepler mission, which has already proven a powerful exoplanet
discovery tool, will benefit greatly from this technique.

Kepler identifies planet candidates by repeatedly measuring the change
in brightness of more than 150,000 stars to detect when a planet passes
in front of, or affects the brightness of, its host star. Speckle
imaging with the Gemini telescope will provide Kepler's follow-up
program with a doubling in its ability to resolve objects and validate
Earth-like planets. It also offers a 3- to 4-magnitude sensitivity
increase for the sources observed by the team. That's about a 50-fold
increase in sensitivity in the observations Howell and his team made at
Gemini. "This is an enormous gain in the effort underway to confirm
small Earth-size planets," Howell added.

To institute this effort Howell and his team - which included Elliott
Horch (Southern Connecticut State University), Mark Everett (National
Optical Astronomy Observatory), and David Ciardi (NASA Exoplanet Science
Institute/Caltech) - temporarily installed a camera, called the
Differential Speckle Survey Instrument (DSSI), among the suite of
instruments mounted on the Gemini telescope.

"This was a fantastic opportunity to bring DSSI to Gemini North this
past July," said Horch. "In just a little over half an hour of Pluto
observations, collecting light with the large Gemini mirror, we obtained
the best resolution ever with the DSSI instrument - it was stunning!"

The resolution obtained in the observations, about 20 milliarcseconds,
easily corresponds to separating a pair of automobile headlights in
Providence, Rhode Island, from San Francisco, California. To achieve
this level of definition, Gemini obtained a large number of very quick
"snapshots" of Pluto and Charon. The researchers then reconstructed them
into a single image after subtracting the blurring effects and
ever-changing speckled artifacts caused by turbulence in the atmosphere
and other optical aberrations. With enough snapshots (each image was
exposed for only 60 milliseconds or about 1/20 of a second) only the
light from the actual objects remains constant, and the artifacts reveal
their transient nature, eventually canceling each other out.

DSSI was built at SCSU between 2007-2008 as a part of a United States
National Science Foundation Astronomical Instrumentation grant and
mounted on the Gemini North telescope for a limited observing run. The
instrument is likely to return to Gemini North for observations in
mid-2013 for general user programs from across the international Gemini
partnership. Any such arrangement will be announced along with the call
for proposals for Semester 13B, in February 2013.

This work was funded in part by the National Science Foundation and
NASA's Kepler discovery mission and will be published in the journal
"Publications of the Astronomical Society of the Pacific" in October 2012.

Background History of DSSI

The Differential Speckle Survey Instrument (DSSI) was built at Southern
Connecticut State University (SCSU) between 2007-2008 as a part of a NSF
Astronomical Instrumentation grant on which Elliott Horch was the
principal investigator. Together with student collaborators, Horch
designed and assembled the instrument, and wrote the instrument control
software. In 2008 DSSI was shipped to the WIYN Observatory at Kitt Peak,
where it has been used since September 2008 for both Kepler follow-up
observations and a NSF-funded project to study binary stars discovered
by Hipparcos. In late 2009, the detectors for the instrument were
upgraded from two low-noise CCDs to two electron-multiplying CCDs, one
purchased by the Kepler Science Office and the other by SCSU. DSSI is
the world's first two-channel speckle imaging instrument.

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Received on Thu 27 Sep 2012 08:25:48 PM PDT