2011 CQ1

2011 CQ₁ is a meteoroid discovered on 4 February 2011 by Richard A. Kowalski, at the Catalina Sky Survey.^[1] On the same day the meteoroid passed within 0.85 Earth radii (5,480 kilometers (3,410 mi) of Earth's surface, and was perturbed from the Apollo class to the Aten class of near-Earth objects.^[5] With a relative velocity of only 9.7 km/s,^[2] had the asteroid passed less than 0.5 Earth radii from Earth's surface, it would have fallen as a brilliant fireball. The meteoroid is between 80 centimeters (31 in) and 2.6 meters (100 in) wide.^[5] The meteoroid was removed from the Sentry Risk Table on 5 February 2011.^[6]

Parameter	Epoch	aphelion (Q)	perihelion (q)	Semi-major axis (a)	eccentricity (e)	Period (p)	inclination (i)	Longitude ascending node (Ω)	Mean anomaly (M)	Argument of perihelion (ω)
Units		AU				(days)	(°)
Pre-flyby	2011-Jan-26	1.347	0.9096	1.128	0.1940	437.9	1.073°	135.4°	310.9°	58.59°
Post-flyby	2011-Feb-08	1.009	0.6624	0.8360	0.2076	279.2	5.296°	315.4°	220.6°	335.1°

2011 CQ₁

Discovery[1]
Discovered by	Catalina Sky Survey Richard A. Kowalski
Discovery date	4 February 2011
Designations
MPC designation	2011 CQ1
Minor planet category	Aten NEO[2]
Orbital characteristics[2]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 5
Observation arc	12.4 hours[3] (35 observations used)
Aphelion	1.0087 AU (150.90 Gm) (Q)
Perihelion	0.66454 AU (99.414 Gm) (q)
Semi-major axis	0.83661 AU (125.155 Gm) (a)
Eccentricity	0.20567 (e)
Orbital period (sidereal)	0.77 yr (279.5 d)
Mean anomaly	18.607° (M)
Mean motion	1.2880°/day (n)
Inclination	5.2445° (i)
Longitude of ascending node	315.23° (Ω)
Argument of perihelion	335.40° (ω)
Earth MOID	0.000166307 AU (24,879.2 km)
Jupiter MOID	4.09715 AU (612.925 Gm)
Physical characteristics
Dimensions	~2 meters (79 in)
Apparent magnitude	14.2 (2011 peak)[4]
Absolute magnitude (H)	32.1[2]

It was not until 2020 QG on 16 August 2020 that a non-impacting closer approach to Earth was observed.

Animation of 2011 CQ1's orbit - 2011 flyby

Around the Sun

Around the Earth

   Sun ·   2011 CQ1 ·   Earth

See also

Closest non-impacting asteroids to Earth, except Earth-grazing fireballs
(using JPL SBDB numbers and Earth radius of 6,378 km)

Asteroid	Date	Distance from surface of Earth	Uncertainty in approach distance	Observation arc	Reference
2020 VT4	2020-11-13 17:21	368 km	±11 km	5 days (34 obs)	data
2020 QG	2020-08-16 04:09	2939 km	±11 km	2 days (35 obs)	data
2021 UA1	2021-10-25 03:07	3049 km	±10 km	1 day (22 obs)	data
2023 BU	2023-01-27 00:29	3589 km	±<1 km	10 days (231 obs)	data
2011 CQ1	2011-02-04 19:39	5474 km	±5 km	1 day (35 obs)	data
2019 UN13	2019-10-31 14:45	6235 km	±189 km	1 day (16 obs)	data
2008 TS26	2008-10-09 03:30	6260 km	±970 km	1 day (19 obs)	data
2004 FU162	2004-03-31 15:35	6535 km	±13000 km	1 day (4 obs)	data