http://news.discovery.com/space/aste...nth-160205.htm
"The near-Earth asteroid 2013 TX68, which is thought to be about 100 feet (30 meters) in diameter, will zoom past our planet on March 5. The space rock could come as close as 11,000 miles (17,700 kilometers) — less than 5 percent of the distance from Earth to the moon — or stay up to 9 million miles (14.5 million km) away during the flyby, NASA officials said."
There are also small chances of an Earth collision during a future passage in 2017.
When it was discovered in 2013, it was only observed for 3 days. Consequently there is a large uncertainty in the orbit. Using the NASA horizons ephemerides generator uses an orbit that places the asteroid at 500 000 km from Earth at mag 15. If however the orbit brings it at the close end of the range, 17,000 km, it could be some 6-8 magnitudes brighter.
The closest flyby as observed from Australia will be overnight on Mar 6th. The March 5 date in the passage quoted above refers to USA times. The current prediction places the asteroid in the vicinity of Regulus all evening. However, if the asteroid does end up being a mere 17000km from Earth, the position could be noticeably different.
Australia has prime viewing with Regulus being above the horizon most of the night straddling the close approach. At mag 15 and with uncertain positioning it will be a challenge to locate. If however it turns out to be brighter, a coordinated series of photographs of the night sky could record it.
Colin Legg recorded the passage of 2012DA14 on his remarkable video
https://vimeo.com/59831086 using a Canon 5D, 50 mm lens, ISO 8000, f/2.2, 8 second shutter, 9 second intervals.
That body was brightening to 7th magnitude during Colin's video however the body was moving at between 10-20 degrees per hour. TX68 is a much slower moving object moving only 1-2 degrees per hour during the night. This allows for much longer exposures with deeper magnitude reach. This project is well within the realm of a mobile observer armed with a DSLR and 50mm lens and one of the many tracking devices or a small mount. A 50mm lens won't give "astrographic" plate scale. At 15-25 arc sec per pixel. However, if the asteroid position could be located and identified by wide field searches and sent through to other observers with astrographic capable instruments, accurate positioning may be possible and this could contribute to greatly improving precision of orbital elements.
If the flyby is very close, 17000 km, the astrographic observers instrument will need to be close to the wide field survey instrument to avoid parallax issues.
Ideally a team of say 3 observers with 6 wide field cameras patrolling a wide swathe of sky, a number of people with computers reviewing the images looking for the asteroid and a couple of observers with astrographic scale instruments to take the precision images.
Having suggested all this, I'd like to participate in such a group exercise myself. However, I'll be in the air that day and evening flying to Indonesia for the Mar 9 solar eclipse. I'll be spending that night at a Jakarta airport hotel and have a very early flight out to eastern Indonesia next morning and as such any participation by me will be impossible.
Joe Cali
