On 15 Feb 2013, a very large fireball was reported over Chelyabinsk, Russia. Peter Brown from the University of Western Ontario, Canada, analyzed infrasound measurements of the event and deduced the following parameters:
A little-known asteroid will skim past Earth on 15 February, passing just 28 000 km from our planet. The 50 m-diameter chunk of space rock was discovered last year by ESA-sponsored amateur astronomers in Spain.
During the last observing run with the ESA 1-m telesope on Tenerife (the OGS = Optical Ground Station) the SSA-NEO programme successfully recovered three 'lost' NEOs. In addition, one new NEO was discovered. The new object has the designation 2013 AS76: From the brightness of the object the size can be estimated to be around 40 - 100 m.
The orbital path of 2011 AG5 has been carefully analyzed in the past year, due to its 1-in-550 probability to pass, during the moderately close approach to the Earth that will take place in early February 2023, through a 365 km wide keyhole leading to a resonant return with impact on the Earth on 5 February 2040.
In the last observing slot at ESA's 1-m telescope on Tenerife, the previously 'lost' object 2009 XZ1 has been recovered. E. Schwab (Germany) has planned and analyzed the observations. The Minor Planet Electronic Circular announcing the recovery can be found here:
In the last SSA-NEO observing run on Tenerife, we have imaged an object on the NEO Confirmation Page called SW40nU (now called comet C/2012 T5), discovered by the Spacewatch survey. It turned out to be a comet. This image shows a stack of all obtained images on 15 Oct 2012 at 23:29 UT, tracked on the object.
A potentially hazardous asteroid once found but then lost has been rediscovered and its orbit confirmed by a determined amateur astronomer working with ESA's space hazards programme. The half-kilometre object will not threaten Earth anytime soon.
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