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[Handsome Rob]

Asteroid 2005 YU55 to Approach Earth on November 8, 2011

Near-Earth asteroid 2005 YU55 will pass within 0.85 lunar distances from the Earth on November 8, 2011. The upcoming close approach by this relatively large 400 meter-sized, C-type asteroid presents an excellent opportunity for synergistic ground-based observations including optical, near infrared and radar data. The attached animated illustration shows the Earth and moon flyby geometry for November 8th and 9th when the object will reach a visual brightness of 11th magnitude and should be easily visible to observers in the northern and southern hemispheres. The closest approach to Earth and the Moon will be respectively 0.00217 AU and 0.00160 AU on 2011 November 8 at 23:28 and November 9 at 07:13 UT.

Discovered December 28, 2005 by Robert McMillan of the Spacewatch Program near Tucson Arizona, the object has been previously observed by Mike Nolan, Ellen Howell and colleagues with the Arecibo radar on April 19-21, 2010 and shown to be a very dark, nearly spherical object 400 meters in diameter. Because of its approximate 20-hour rotation period, ideal radar observations should include tracks that are 8 hours or longer on multiple dates at Goldstone (November 3-11) and when the object enters Arecibo's observing window on November 8th.

Using the Goldstone radar operating in a relatively new "chirp" mode, the November 2011 radar opportunity could result in a shape model reconstruction with a resolution of as fine as 4 meters. Several days of high resolution imaging (about 7.5 meters) are also planned at Arecibo. As well as aiding the interpretation of the radar observations, collaborative visual and near infrared observations could define the object's rotation characteristics and provide constraints upon the nature of the object's surface roughness and mineral composition.

Since the asteroid will approach the Earth from the sunward direction, it will be a daylight object until the time of closest approach. The best time for new ground-based optical and infrared observations will be late in the day on November 8, after 21:00 hours UT from the eastern Atlantic and western Africa zone. A few hours after its close Earth approach, it will become generally accessible for optical and near-IR observations but will provide a challenging target because of its rapid motion across the sky.

[scouterjim]

Asteroid 2005 YU55 to Approach Earth on November 8, 2011

Will it usher in the rapture?

[Sir Bandelot]

As an amateur astronomer I can tell you, this type of event (an asteroid passing between the Earth and Moon) is not unusual. It's happened numerous times before. Generally they are hard to observe for amateurs because they are so tiny. Not much detail can be resolved that would be of any real interest. Also, they travel on an unusual trajectory and require some skill to track across the sky. And they are often very dim. In this case "magnitude 11" indicates the brightness, which is not out of reach for some backyard scopes.

[Handsome Rob]

As an amateur astronomer I can tell you, this type of event (an asteroid passing between the Earth and Moon) is not unusual. It's happened numerous times before. Generally they are hard to observe for amateurs because they are so tiny. Not much detail can be resolved that would be of any real interest. Also, they travel on an unusual trajectory and require some skill to track across the sky. And they are often very dim. In this case "magnitude 11" indicates the brightness, which is not out of reach for some backyard scopes.

Any tips? I've got a 6 inch Dob, have seen all planets out as far as Saturn. I think I managed to get the Orion nebula, but still unsure. If it was it didn't look spectacular or I had crappy conditions. Tried M31 @ 48x many times to no avail.

What are you looking at this time of year?

[bush_cheney2004]

Any tips? I've got a 6 inch Dob, have seen all planets out as far as Saturn. I think I managed to get the Orion nebula, but still unsure. If it was it didn't look spectacular or I had crappy conditions. Tried M31 @ 48x many times to no avail.

At magnitude 11, the asteroid would be visible in a well collimated Newtonian reflector (Dob mount). Consider that Saturn's moon Titan is about magnitude 8 and the center star of M57 (Ring Nebula) is about mag 15, just beyond the reach of a 150mm telescope unless you have a lot of experience with averted vision and dark adaptation.


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You will need a star map to discern the asteroid from background stars (Sky & Tel magazine usually publishes these in observer guides).

What are you looking at this time of year?

Saturn rules the night sky, close to the "Realm of the Galaxies" in Virgo's bowl. Summer favorites are just now visible later in the evening, including M13 in Hercules. Lots to see, but watch out for the skeeters!