1999 SF10

1999 SF₁₀ is a small, quickly rotating unnamed near-Earth asteroid (NEA). First observed on 30 September 1999 by the Lincoln Near-Earth Asteroid Research (LINEAR) program in Socorro, New Mexico, United States, it is an Earth-crossing Apollo asteroid. Its diameter is estimated to be around 60 metres (200 ft) in size with a very rapid rotation period of 2.47 minutes, indicating that it is a monolithic object.

1999 SF₁₀

Discovery[1][a]
Discovery date	30 September 1999 (Initial reported obs.)
Designations
MPC designation	1999 SF10
Minor planet category	NEO · Apollo
Orbital characteristics[2]
Epoch 21 November 2025 (JD 2461000.5)
Uncertainty parameter 0
Aphelion	1.6039 AU
Perihelion	0.9550 AU
Semi-major axis	1.2795 AU
Eccentricity	0.2536
Orbital period (sidereal)	1.4473 y (528.62 d)
Mean anomaly	1.251°
Mean motion	0.6810° / d
Inclination	1.2081°
Longitude of ascending node	25.817°
Argument of perihelion	27.975°
Earth MOID	0.0038 AU
TJupiter	5.026
Physical characteristics
Dimensions	85 m × 55 m[3]: 150
Mean diameter	60 m
Sidereal rotation period	2.4663±0.0005[4]: 481
Geometric albedo	0.117[3]: 150
Absolute magnitude (H)	24.46[2]

History

1999 SF₁₀ was first observed on 30 September 1999 by the Lincoln Near-Earth Asteroid Research (LINEAR) program from its Experimental Test Site (ETS) in Socorro, New Mexico, United States.^[1] It was given the provisional designation 1999 SF₁₀ by the Minor Planet Center (MPC), and its detection was announced in a Minor Planet Electronic Circular on 4 October 1999.^[5] At the time of its first observation, it was rapidly approaching Earth, and on 12 October it passed within a distance of 0.0076 astronomical units (AU; 3.0 LD).^[4]: 481

As of 2025^[update], it has not been numbered or named by the MPC.^[2] It also has not been formally assigned a discoverer, which will happen when it is numbered.^[1]

Orbit

Diagram showing 1999 SF₁₀'s orbit in the inner Solar System. The ecliptic grid is shown.

1999 SF₁₀ is classified as a near-Earth asteroid (NEA). It orbits the Sun at an average distance—its semi-major axis—of 1.28 AU, taking 1.45 years to complete one revolution. It has a low orbital inclination of 1.45° relative to the ecliptic plane. Along its orbit, its distance from the Sun varies between 0.96 AU at perihelion to 1.60 AU at aphelion due to its orbital eccentricity of 0.25.^[2] Because its perihelion lies below 1 AU, it is also classified as an Earth-crossing Apollo asteroid.^[6][2]

Physical characteristics

1999 SF₁₀ has an estimated mean diameter of 60 metres (200 ft) with dimensions of 85 by 55 metres (279 ft × 180 ft), assuming a geometric albedo of 0.110–0.117; its estimated size may be off by a factor of 2.^{[4]: 481 [3]: 150} Observations of its lightcurve, or variations in its observed brightness, suggest that it has a rotation period of 2.47 minutes,^[4]: 481 classifying it as a monolithic fast-rotating asteroid (MFRA).^[3]: 150 MFRAs have rotation periods much faster than those typically observed in asteroids, rotating faster than the critical period below which a strengthless body will self-destruct due to centrifugal forces.^[3]: 148

See also

• List of fast rotators (minor planets)

Notes

1. Discoverer not yet assigned by the MPC