732 Tjilaki (prov. designation: or ) is a dark background asteroid, approximately in diameter, located in the inner region of the asteroid belt. It was discovered by German astronomer Adam Massinger at the Heidelberg Observatory on 15 April 1912, and later named after the Cilaki (Tjilaki) river in Indonesia. The dark D-type asteroid has a rotation period of 12.3 hours. It was an early candidate to be visited by the Rosetta spacecraft which eventually rendezvoused comet 67P/Churyumov–Gerasimenko. Orbit and classification Tjilaki is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the inner asteroid belt at a distance of 2.3–2.6 AU once every 3 years and 10 months (1,406 days; semi-major axis of 2.46 AU). Its orbit has an eccentricity of 0.04 and an inclination of 11° with respect to the ecliptic. The body's observation arc begins at Heidelberg Observatory on 28 August 1913, or 16 months after its official discovery observation. Naming This minor planet was named after the Cilaki (Tjilaki) river in West Java, Indonesia. The river rises in the mountains where the city of Malabar (see asteroid 754 Malabar) is located. The was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (). Rosetta mission In the Phase A study of the Rosetta mission, Tjilaki was considered an alternative visiting target to comet 46P/Wirtanen. However, both candidates were later abandoned in favor of comet 67P/Churyumov–Gerasimenko, which was visited by Rosetta in 2014. The retargeting was necessary as the spacecraft's launch window changed due to a delay caused by the launch failure of the satellite on the maiden flight of the Ariane 5 ECA carrier rocket in 2002. Physical characteristics In both the Tholen- and SMASS-like taxonomic variants of the Small Solar System Objects Spectroscopic Survey (S3OS2), , Tjilaki is a dark D-type asteroid, uncommon in the inner but abundant in the outer asteroid belt as well as among the Jupiter trojan population. Polarimetric observations also determined a D-type. Rotation period and poles In February 1996, a rotational lightcurve of Tjilaki was obtained from photometric observations over ten nights by European astronomers using the Dutch 0.9-metre Telescope and the Bochum 0.61-metre Telescope at La Silla Observatory in Chile. Lightcurve analysis gave a rotation period of hours with a brightness variation of magnitude (). In May 2012, astronomers at