Sig nærmer tiden…

her er et oversigtskort:

http://martinmobberley.co.uk/images/2005YU55chart_mpm.jpg

og seneste info fra BAA:

Seen from the UK on the evening of Tuesday, November 8/9, a 400-metre size asteroid 2005 YU55 will pass within 0.85 lunar-distances of us travelling at a speed of 13.7 km/s relative to the Earth. This encounter will be the closest known for an asteroid of this size between the years, 1976 and 2028.

So in this respect, it is a once in a 52-year opportunity to witness this particular skirmish.

It should first become visible from the UK and Europe on Tuesday evening, low in the west mainly in Aquila, passing 22 degrees south-west of Comet Garradd (C/2009 P1). It should prove fascinating to follow as it approaches.

Seen from southern England (Dorset), it may be first detectable using a CCD camera and large telescope at about 18:00UT some 23 degrees altitude in the south-west direction at about magnitude 15 moving at 5 “/sec. It will brighten by about a factor of 10 over the next 4 hours so that by 22:00UT it will be 12th magnitude and moving at around 8 “/sec, i.e. crossing the sky at a rate of 1 Moon-diameter every 3.6 minutes.

Even exposures of a few seconds will show the asteroid as a trail and only telescope mounts set up to track moving objects will be able to register it as a point source.

It will attain 11th magnitude at closest approach (Nov 8 at 23:28UT) at an altitude of just 6 degrees (as seen from Dorset) and thereafter will set below the western horizon. With a very high apparent speed (reaching almost 9 “/sec), the object will be visible through large telescopes (25cm or greater) looking like a moving point of light crossing the field of view in a minute or two. Quite an observing challenge!

2005 YU55 will be much better placed for observers and easier to see on the evening of November 9/10 when at about 18:00UT it will be 12th magnitude and moving at <1 “/sec in the east close (12 degrees away) to the nearly full Moon.