Asteroid 2011 GP59 – Close Earth-Moon Flyby

Newly-discovered asteroid 2011 GP59 is flying past Earth today, April 15th, not far beyond the orbit of the Moon (1.4 LD). There’s no danger of a collision, but the 50-meter space rock is remarkable: It is elongated and spinning once every 7.5 minutes. This causes the asteroid to flash like a strobe light.A video taken by Joe Pollock of Appalachian State University on April 11th shows the effect nicely. Experienced amateur astronomers using mid-sized telescopes can watch 2011 GP59 strobe through the constellations Virgo and Hydra tonight with a peak brightness near 13th magnitude. (SpaceWeather)

The Mpec circular 2011-G60 issued on April 09, 2011 announced the discovery of a new Aten asteroid officially designated 2011 GP59. This asteroid (~ magnitude 17.5) was discovered by La Sagra Surveythrough their 0.45-m f/2.8 reflector + CCD, on images obtained on April 08.9, 2011. After posting on the Minor Planet Center’s ‘NEOCP’ webpage, other CCD astrometrists have been able to follow-up the new object to define its orbit.

According to the preliminay orbit, 2011 GP59 is an Aten type asteroid. This class of asteroids are defined by having semi-major axes of less than one astronomical unit (the distance from the Earth to the Sun). 2011 GP59 will have a close approach with Earth on April 15, 2011 at 1909 UTC at rougly 0.003567AU or 1.39 LD (Lunar Distance) reaching the magnitude ~13. Its absolute magnitude H=24.30 correspond to an approximate diameter of 50 meters.

2011 GP59 shows evident . Below you can see a light-curve made by Brian Skiff (Lowell Observatory): 6-hours of observations using the Lowell 0.55-m Schmidt with 45-second exposures showing an amplitude in excess of 2 full magnitudes over a period of roughly 7.5 minutes. (RemanzaccoObservatory)

2011 GP59 – JPL Solar System Dynamics