2012 KT42 was discovered earlier today May 28 by the Mt. Lemmon Survey’s 1.5-meter (59-inch) reflecting telescope north of Tucson, Arizona. The tiny asteroid was only 18th magnitude and estimated at between 10-30 feet wide. While posing no threat, it’s moving rapidly towards closest approach to Earth around 2:10 a.m. CDT tomorrow morning May 29, when it will fly by at the slim distance of 8,700 miles. That would make 2012 KT42 the 6th closest asteroid approach to date. Click HERE to see a list of Top 20 closest approaches.
Savvy amateurs with 6-inch telescopes and larger should be able to see it shining between 12th and 13th magnitude late tonight through tomorrow morning. Watch out though – the asteroid will move very rapidly across the sky. You’ll need to download its orbital elements at this site and put them into a sky-charting program, so you can make a detailed map to find and follow the zippy rock. Or … you can go to the same site, click the Ephemeris heading, select the date and time interval and then click the Generate Ephemeris button to create a list of positions you can hand plot on a sky chart.
Once you do find it, don’t let go. You’ll be on a fast train. When closest, 2012 KT42 will be traveling at over 2 arc minutes per second. Two arc minutes is more than twice as big as Jupiter appears through a telescope. That’s plenty fast enough to see move in real time.
Between 1 and 3 a.m. CDT, 2012 KT42 will travel from the constellation Libra in the southern sky all the way to Auriga in the far north!
Viewers along a path that cuts across central Asia and Africa will see the asteroid transit the sun at around 5:10 CDT May 29. It’ll be interesting to see if anyone can spot it through a telescope given its minute size.