(9992) 1997 TG19

 is a stony asteroid and eccentric Mars-crosser, approximately 4 kilometers in diameter. It was discovered on 8 October 1997, by Japanese astronomers Tetsuo Kagawa and Takeshi Urata at Gekko Observatory near Shizuoka, Japan.

Orbit and classification


The stony S-type asteroid orbits the Sun at a distance of 1.5–2.8 AU once every 3 years and 2 months (1,169 days). Its orbit has an eccentricity of 0.29 and an inclination of 3° with respect to the ecliptic. The first used observation was made at the Cerro El Roble Station in 1974, extending the asteroid's observation arc by 23 prior to its discovery.

Lightcurves
Between 2006 and 2013, three rotational lightcurves for this asteroid were obtained from photometric observations made at the  Hunters Hill Observatory, Australia, the Ondřejov Observatory, Czech Republic, and the U.S. Palomar Transient Factory, California. They gave a well-defined, concurring rotation period of $4.75$ hours (best result) with a brightness amplitude of 0.42, 0.40 and 0.27 in magnitude, respectively (U=3/3/2).

Diameter and albedo
According to the survey carried out by the Japanese Akari satellite, the asteroid's surface has an albedo of 0.13 and a diameter of 4.75 kilometers. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 3.1 kilometers, as the higher the body's albedo (reflectivity), the shorter its diameter, at a constant absolute magnitude (brightness).

Numbering and naming
This minor planet was numbered by the Minor Planet Center on 2 February 1999. As of 2018, it has not been named.