Discovered by the Catalina Sky Survey on 2012 Aug 26, this relatively large near-Earth asteroid will be readily observable for northern hemisphere observers between September 4-14 during which time it will attain magnitude 15.0 or brighter.
The object probably measures between 200-500 m across and is a current radar target. It will be brightest around September 10-12 when it will reach V=13.6 on average. It passes closest to us around 05h UT on September 14 at a range of about 7.4 lunar-distances (0.019 AU).
2012 QG42 is a potentially hazardous asteroid (PHA) and is unusual in that it passes very close to the opposition point on September 7. The circumstances of this close approach therefore makes this object a good target for photometry (using a V, R or r’ filter if possible) as well as other physical studies. An ephemeris with visibility details for UK observers is available at:
http://www.britastro.org/~rmiles/Documents/2012QG42_MPC_J77.txt
