Asteroid approach shrank to 14,000 miles this a.m. + NASA says "Astrometry is URGENTLY Needed"

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[link to echo.jpl.nasa.gov]

ASTROMETRY IS URGENTLY NEEDED

2012 DA14 was discovered by the La Sagra Sky Survey in Spain on February 23, 2012. This object will make an extremely close approach to within 0.00023 AU of Earth at 19:25 UT (11:25 AM PST) on February 15, 2013. That is only 0.09 lunar distances or 5.4 Earth radii from the center of the Earth. The close approach will be about 28000 km above Earth's
surface. That's inside the distance to geosynchronous satellites but thousands of kilometers above the elevation for low-Earth-orbit spacecraft such as the International Space Station.
At the time of closest approach, the asteroid will move about 0.8 degrees per minute.

The uncertainties in plane-of-sky position, Doppler frequency, and time delay will grow dramatically
during the approach, but even so, this object cannot impact Earth during this encounter.

2012 DA14's absolute magnitude of 24.4 suggests a diameter within a factor of two of about 50 meters.
Nick Moskovitz (Carnegie Institution, Washington, DC) reported that he obtained lightcurves and
spectroscopy shortly after 2012 DA14 was discovered. The asteroid has a rotation period of about 6 hours
and it's an L-class object, hinting that it has an optical albedo of about 0.2. The lightcurve
amplitude is close to one magnitude, so the shape is probably elongated. Nothing else is known
about this object.

Due to the extremely close approach, this object will be a very strong radar target at Goldstone
and we plan to image it with the highest resolution available (3.75 meters) from the chirp system.
The round-trip time on the first track on Feb. 16 is so short that observations on that day
will be bistatic with reception of radar echoes at DSS-13.

2012 DA14 will approach from the south and will enter Goldstone's declination window on February 16, 2013,
shortly after the closest approach. Afterward it will be a circumpolar object as it recedes from Earth.

Radar observations at Goldstone are scheduled on 2013 Feb. 16, 18, 19, and 20.

We need additional astrometry to improve the orbit. As a result, below we list circumstances for optical
observations starting many months before the encounter in order to help facilitate observations
by optical observers. The apparent magnitudes will be fainter than 22nd until until the beginning of
February, but the solar elongation will be only about 60 degrees, so obtaining optical astrometry
will be challenging. In addition, the asteroid will be at far southern declinations until Feb. 15
when it will move from about -75 deg to +75 deg in only a few hours.

This object will not be observable at Arecibo.

2012 DA14 will brighten to about 7th magnitude at the time of the closest approach, when observers
in Asia might be able to see it with binoculars and small telescopes. Doing so will require
knowing very precisely where to look and will require a site-specific ephemeris due to parallax.

2012 DA14 is too small to be classified as a "Potentially Hazardous Asteroid" (PHA) by the Minor
Planet Center.

Radar observations are also planned by other researchers at the EISCAT radar near Tromso, Norway
starting at 20:00 UT on Feb. 15 and at the Haystack Observatory in Massachusetts starting at 22:00 UT
on Feb. 15. Goldstone observations start at 03:00 UT on Feb. 16, several hours after observations
begin at the other radars.