9994 Grotius
9994 Grotius , provisional designation , is a stony Rafita asteroid from the middle regions of the asteroid belt, approximately 3.5 kilometers in diameter. It was discovered during the Palomar–Leiden survey in 1960, and named after Dutch jurist Hugo Grotius. Discovery. "Grotius" was discovered on 24 September 1960, by the Dutch astronomers Ingrid and Cornelis van Houten, on photographic plates taken by Dutch–American astronomer Tom Gehrels at Palomar Observatory in California, United States. Survey designation. The survey designation "P-L" stands for "Palomar–Leiden", named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden  survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets. Orbit and classification. "Grotius" orbits the Sun in the central main-belt at a distance of 2.1–3.0 AU once every 4 years and 2 months (1,518 days). Its orbit has an eccentricity of 0.18 and an inclination of 7° with respect to the ecliptic. The body's observation arc  begins with its official discovery observation at Palomar. Rotation period. In August 2010, a rotational lightcurve of "Grotius" was obtained from photometric observations in the R-band at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 9.2189 hours with a brightness variation of 0.27 magnitude (). Diameter and albedo. According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, "Grotius" measures 3.746 kilometers in diameter and its surface has an albedo of 0.263. The "Collaborative Asteroid Lightcurve Link" assumes a standard albedo for stony asteroids of 0.20 and  calculates a diameter of 3.38 kilometers based on an absolute magnitude of 14.72. Naming. This minor planet was named for Dutch jurist Hugo Grotius (1583–1645), who laid the foundations for international law, based on natural law. He was a child prodigy and entered Leiden University when he was just eleven years old. The approved naming citation was published by the Minor Planet Center on 11 November 2000 ().