Imaging of Near-Earth Asteroid 2005 YU55 at Keck Observatory on the night of 2011 Nov 8 Hawaii Time (2011 Nov 9 UT)

Information on live webcast from Keck and other feeds

Start time approx 7pm Hawaii Standard Time, 10pm Mountain Time

Posted Nov 9 - Link to Discovery News -- Click for results: First Infrared Pictures of 2005 YU55

Highlighted by Discovery News as one of 18 "Cosmic Hot Shot" Images from Keck

Correction: Actual UT date is Nov 9, not Nov 8.
PRELIMINARY, UNPROCESSED image from Keck. Final size estimate will change substantially from the "apparent" size shown here.

Note added Nov 9 :
Although some press reports are listing a size of 240m, that is a misinterpretation of this image. The 240m is meant to be a scale bar, not an indication of the size of the asteroid. Our preliminary analysis indicates that the asteroid is somewhat smaller than the 400m expected, but not as small as the 240m bar here. The Sun is not fully illuminating the asteroid here (partial phase) and the stretch (constrast) of this raw image is adjusted to try to best convey the non-spherical shape of the asteroid, rather than to show its size.

Observation Credits: W. Merline (SwRI), P. Tamblyn (SwRI), C. Neyman (Keck), Keck Observatory, NASA, & NSF

Note added Nov 13 : Modeled as a triaxial ellipsoid, our initial solution for the size is 340 x 325 x 270 m, these values resulting from rounding to the nearest 5 m in each dimension.
The number of sig figs given is not indicative of the expected uncertainties, and no uncertainties are quoted or implied here.
The spherical-equivalent radius would then be 308 m, again with no uncertainty offered at this point.
(analysis by Drummond and Carry)

Our observations cover only 55 deg rotation (on the assumption of an 18h spin period) and therefore one of the dimensions could, by happenstance, be both larger and mostly hidden. In general, our preliminary analysis bears out our 3 initial impressions:
1) there are significant deviations from spherical shape,
2) there are no obvious satellites, at least of the type (size and separation) typical for NEAs, and
3) the asteroid is smaller than the expected 400 m



On the night of Tuesday 2011 Nov 8, we will be attempting the first well-resolved optical images of a near-Earth asteroid from the Keck 2 Telescope in Hawaii. This is the world's largest optical telescope. The large size of the telescope, plus its adaptive optics system, will allow us to measure its size and shape and determine the direction of its spin pole. We will also be searching for moons around the asteroid. But we have significant hurdles to overcome: 1) the asteroid is moving at a very fast speed across the sky, faster than we have tracked previously, 2) the weather must cooperate, with minimal clouds, no rain/snow, no high humidity or excessive wind, 3) the atmospheric conditions must be ideal to allow the adaptive optics (which removes the blurring of Earth's atmosphere) to work properly. For those familiar with the term, this means the "seeing" must be good. We have a forecast for 0.5-0.9 arcsec seeing, which would be good at most sites, but at Mauna Kea, that is considered only fair. Here you can see live links to our progress and allow you to follow along. Further below are some pictures we have acquired with the Keck telescope. Eventually, we may post the first picture of 2005 YU55 from Keck (other radar images have already Been made public and can be seen in some of the links here).

Link to Keck Press Release and to LIVE WEBCAST and Facebook/Twitter Feeds

From above, Discovery News will start at 5pm PST

WEATHER conditions, current

On-site team:

Dr. Bill Merline (Southwest Research Institute [SwRI], Boulder, CO)
Dr. Peter Tamblyn (SwRI, Boulder)
Dr. Chris Neyman (W.M. Keck Observatory, Kamuela, HI

Off-site direct participants, expected to join via Skype:

Dr. Benoit Carry (ESA, Madrid, Spain)
Dr. Al Conrad (Max Planck Institute, Heidelberg, Germany)
Dr. Jack Drummond (Air Force Research Lab, Albuquerque, NM)

Other participants:
Dr. Clark Chapman (SwRI, Boulder)
Brian Enke (SwRI, Boulder)
Dr. Dan Durda (SwRI, Boulder)
Dr. Bill Owen (JPL, Pasadena, CA)
Dr. Julian Christou (Gemini Observatory, Hawaii)
Dr. Christophe Dumas (European Southern Observatory, Chile)

Some other links for information:

Background and Planning - mostly for radar
Nov 7 NASA Press Release with new radar image

Some of our pictures from Keck Adaptive Optics including an NEO binary

No site would be complete without a glimpse of the challenges of science atop the world's tallest mountain: Hotel Mauna Kea

Here are some pictures of the Keck telescopes on Mauna Kea, at 14,000 ft above sea level and the highest mountain on Earth, measured from its base below the ocean. The primary mirror is shown and is 10 meters (33 feet) in diameter. Some of the pictures show the powerful laser that is used to create an artificial star in Earth's upper atmosphere. This is used to measure the distortion caused by the atmosphere so that it can be corrected.