2011 CQ1 - Very Close Approach

The newly discovered object, officially designated 2011 CQ1, will make a close Earth approach today February 04, 2011 around 19:40UT at ~0.03(LD)/0.00008(AU) or 11855 km.

2011 CQ1 has been discovered by R. A. Kowalski few hours ago in the course of the "Catalina Sky Survey" with a 0.68-m Schmidt + CCD. The object was moving at roughly 6 "/min and it was of magnitude ~19. According to its absolute magnitude H=32 this is a very small object, in the order of 2-3 meters.

Just few hours after his discovery, we have been able to follow-up this object using remotely a 0.35-m f/3.8 reflector + CCD of "Tzec Maun Observatory" in New Mexico. At the moment of our images (on February 04.46), "2011 CQ1" was moving at 23"/min and its magnitude was ~18.

Here you can see our image (stacking of 20 unfiltered exposures, 10 seconds each). Click on the image for a bigger version:




While this is an animation showing the object movement in the sky:

According to Bill Gray (Findorb developer): "That perigee value is solid to within a few kilometers. So no chance of an impact, but still _very_ close!!"


The orbital element published here, are very interesting:

2011 CQ1
Perigee 2011 Feb 4.818749 TT = 19:38:59 (JD 2455597.318749)
Epoch 2011 Feb 4.8 TT = JDT 2455597.3 Find_Orb
q 11855.6869km (2000.0) P Q
H 32.1 G 0.15 Peri. 156.15870 -0.32177738 -0.84067340
Node 92.60696 -0.92360962 0.17747398
e 1.7936521 Incl. 25.85075 -0.20833766 0.51163581
From 11 observations 2011 Feb. 4 (6.3 hr); mean residual 0".362.


As shown by the ephemeris, 2011 CQ1 will be visible for a few hours. It would be really interesting to follow-up this object in the next few hours, during its very close approach when it will reach the magnitude 14!


UPDATE - February 04, 2011 - 19:35UT

On mpml mailing list, Andrew Lowe pointed out that "that 2011 CQ1 will transit the sun shortly after its close approach. Based on astrometry up to MPEC 2011-C14, its "centre line" will start to cross the earth at Feb. 4.831 UT around N11 E160, with mid-transit at Feb 4.844 (S24 W125; south Pacific) and ending at Feb 04.858 (S29 W30)"

Andrew has supplied three coordinates on the centerline:

First contact: Feb 4.831 UT 11N, 160E (west of the Marshall Islands,
near Enewetak)

Mid-transit: Feb 4.844 UT 24S, 125W (French Polynesia, east of
Pitcairn Island)

Final contact: Feb 4.858 UT 29S, 30W (south Atlantic, off the coast
of Brazil)

Following this suggestion, Bill Gray calculated a transit line plot showing the path over South America. You can see the charts below:

Credit: B. Gray

UPDATE - February 05, 2011 - 09:30UT

According to a press release by NASA/JPL, 2011 CQ1 is "the closest non-impacting object in our asteroid catalog to date. It passed to within 0.85 Earth radii (5480 km) of the Earth's surface over a region in the mid-Pacific"

Prior to the Earth close approach, this object was in a so-called Apollo-class orbit that was mostly outside the Earth's orbit. Following the close approach, the Earth's gravitational attraction modified the object's orbit to an Aten-class orbit where the asteroid spends almost all of its time inside the Earth's orbit.

NASA press release contains this diagram where is evident how the close Earth approach changed the asteroid's flight path by about 60 degrees:

Credit: Nasa/JPL

By Giovanni Sostero & Ernesto Guido