(85713) 1998 SS49 is an asteroid on an eccentric orbit, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 3 kilometers (1.9 miles) in diameter. The asteroid was discovered on 29 September 1998, by astronomers of the LINEAR program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States. It is one of the largest potentially hazardous asteroids and has a notably low Earth-MOID of less than the distance to the Moon.

Orbit and classification

1998 SS49 is a member of the dynamical Apollo group, which are Earth-crossing asteroids. Apollo asteroids are the largest subgroup of near-Earth objects.

It orbits the Sun at a distance of 0.7–3.2AU once every 2 years and 8 months (975 days; semi-major axis of 1.92AU). Its orbit has a high eccentricity of 0.64 and an inclination of 11° with respect to the ecliptic. The body's observation arc begins with its official discovery observation at Socorro in September 1998.

Close approaches

At about absolute magnitude 15.6, 1998 SS49 is one of the brightest and presumably largest known potentially hazardous asteroid (see PHA-list). It has a very low Earth minimum orbital intersection distance of 0.0023AU(340thousandkm; 0.90LD). On 26 November 1902, this asteroid made its closest near-Earth encounter since 1900 at a nominal distance of 0.0659AU(9.86millionkm; 25.6LD). The next notable close approach was on 21 November 2022, passing at a nominal distance of 0.141AU (21,100,000km; 13,100,000mi).

1998 SS49 is also a Venus- and Mars-crosser, as it crosses the orbit of Venus and the Red Planet at c. 0.72 and 1.66AU, respectively.

Physical characteristics

1998 SS49 is an assumed, stony S-type asteroid.

Rotation period

In 2014, two rotational lightcurves of 1998 SS49 were obtained from photometric observations by American astronomer Brian Warner at the CS3–Palmer Divide Station in California (U82). Lightcurve analysis gave a rotation period of 5.370 and 5.66 hours and a brightness variation of 0.18 and 0.06 magnitude, respectively (U=2/2), one of which gave an alternative period solution of 2.686±0.002 hours. In April 2016, the EURONEAR lightcurve survey measured a period of 5.398 hours with an amplitude of 0.12 magnitude (U=2).

Diameter and albedo

Surveys contrast: of the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer. These measure the object as between 2 and 3.484 kilometers lengthways (in diameter) and to have an albedo (optical wavelength reflectivity) between 0.076 and 0.237. The Collaborative Asteroid Lightcurve Link assumes a stony typical albedo of 0.20 to calculate the diameter as 2.25 kilometers and an absolute magnitude of 15.6.

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 30 August 2004. As of 2018, it has not been named.

Notes

External links