(10115) 1992 SK

(10115) 1992 SK, is a stony near-Earth object and potentially hazardous asteroid on an eccentric orbit. It belongs to the group of Apollo asteroids and measures approximately 1 kilometer (0.6 miles) in diameter. It was discovered by American astronomers Eleanor Helin and Jeff Alu at the Palomar Observatory in California on 24 September 1992.^[2]

(10115) 1992 SK

Discovery[1]
Discovered by	E. F. Helin J. Alu
Discovery site	Palomar Obs.
Discovery date	24 September 1992
Designations
MPC designation	(10115) 1992 SK
Alternative designations	1992 SK · 1985 SD 1985 TO2
Minor planet category	Apollo · NEO · PHA[1][2]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	63.57 yr (23,219 days)
Aphelion	1.6539 AU
Perihelion	0.8429 AU
Semi-major axis	1.2484 AU
Eccentricity	0.3248
Orbital period (sidereal)	1.39 yr (509 days)
Mean anomaly	47.505°
Mean motion	0° 42m 23.76s / day
Inclination	15.322°
Longitude of ascending node	8.9232°
Argument of perihelion	233.63°
Earth MOID	0.0449 AU · 17.5 LD
Physical characteristics
Mean diameter	0.90±0.20 km[3] 0.938±0.294 km[4] 1.000±0.085 km[5] 1.0±0.2[6] 1.18 km (calculated)[7]
Synodic rotation period	7.31±0.02 h[8] 7.31832 h[9] 7.319 h[7] 7.323±0.005 h[10] 7.328±0.002 h[a] 7.320232±0.000010 h[6]
Geometric albedo	0.20 (assumed)[7] 0.2799±0.1397[5] 0.318±0.214[4] 0.34±0.25[3] 0.38±0.24[11]
Spectral type	SMASS = S[1] · S[7] · S/Sq[12]
Absolute magnitude (H)	17.0[1][4][5][7] · 17.4[a]

Classification and orbit

The asteroid orbits the Sun at a distance of 0.8–1.7 AU once every 17 months (509 days). Its orbit has an eccentricity of 0.32 and an inclination of 15° with respect to the ecliptic. Its Earth minimum orbit intersection distance is 0.0449 AU (6,720,000 km). This makes the body a potentially hazardous asteroid, because its MOID is less than 0.05 AU and its diameter is greater than 150 meters.^[1] The first precovery was obtained at Palomar Observatory in 1953, extending the asteroid's observation arc by 39 years prior to its discovery.^[2]

Physical characteristics

In the SMASS classification, 1992 SK is characterized as a common stony S-type asteroid.^[1]

Rotation period

Several rotational lightcurves form photometric observations have been obtained for this body. In 1999, Czech astronomer Petr Pravec constructed a lightcurve, that rendered a rotation period of 7.328 hours and a brightness variation of 0.72 in magnitude (U=n/a).^[a]

In March 2006, observations by astronomer David Polishook from the ground-based Wise Observatory, Israel, gave a rotation period of 7.31 and amplitude of 0.70 mag (U=2),^[8] and in November 2011, American astronomer Brian Warner at the Palmer Divide Observatory, Colorado, obtained the first well-defined period of 7.323 hours with an amplitude of 0.50 mag (U=3).^[10]

The rotation period of 1992 SK is slowly accelerating due to the YORP effect.^[6]

Diameter and albedo

According to the surveys carried out by NASA's space-based Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures 1.0 and 0.94 kilometers in diameter and its surface has an albedo of 0.28 to 0.32, respectively.^[4][5] The ExploreNEOs project finds an albedo of 0.34, with a diameter of 0.9 kilometers,^[3] and the Collaborative Asteroid Lightcurve Link calculates a diameter of 1.18 kilometers based on an assumed standard albedo for stony asteroids of 0.20 and an absolute magnitude of 17.0.^[7]

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 2 March 1999.^[13] As of 2019^[update], it has not been named.^[2]

Notes

1. Pravec (1999) web: rotation period 7.328±0.002 hours with a brightness amplitude of 0.72 mag. Two more light-curves rendered similar periods. No quality rating by CALL. Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (10115)