Wednesday 20 February 2013

Partial lightcurve for 2012 DA14

On the night after closest approach, when the apparent motion had slowed down to around 15"/min and magnitude faded to about +15, three hours of photometric observations were obtained, the diagram below indicating that just a part of the overall rotational lightcurve had been captured, showing a rise to magnitude +14.3R, followed by a fall to +15.9R.

Radar results for 2012 DA14 obtained from NASA's Goldstone facility and qualified by Dr. Lance Benner on MPML indicate a rotation period of "probably somewhat longer than 8 hours".

2012 DA14: 3 hours of lightcurve covering 2013 Feb. 16th 21:10 UT  - 17th 00:11 UT
PPMXL catalogue used for reductions, error bars derived from measured S/Nr are shown

Update 20/2/2013 20:35UT: A much more complete lightcurve by Bruce Gary from Hereford Arizona Observatory (G95)  can be seen here, covering about 10 hours of observing, yielding a rotation period of just over 9 hours.

Friday 15 February 2013

2012 DA14 makes its very close fly-by of Earth

2012 DA14 captured on its way out from its very close encounter with Earth.

The NEO was 8th magnitude and moving at 1,645"/minute when these images were obtained and was nine times closer than the Moon. At its closest at 19:24 UT on 15th Feb. 2013 it had come inside the geostationary satellite ring but by the time these images were taken 80 minutes later it had already passed back outside.

2012 DA14 1hour and 20 minutes after closest approach to Earth

Exposures were limited to 0.2 seconds to stop the asteroid from trailing so the images could be used to measure the object's position.

A few gaps in thickening clouds only allowed a short run of images to be captured between 20:43 - 21:00 UT,  before the sky completely clouded over.