6084 Bascom

Lore & Background

Bascom is a stony S-type asteroid and member of the Phocaea family (701), a group of asteroids with similar orbital characteristics. It orbits the Sun in the inner main-belt at a distance of 1.8–2.9 AU once every 3 years and 6 months (1,286 days). Its orbit has an eccentricity of 0.24 and an inclination of 23° with respect to the ecliptic. A first precovery was taken at Palomar in 1950, extending the body's observation arc by 30 years prior to its official discovery observation.

Between 29 December 2005 and 2 February 2006, the first ever rotational lightcurve was obtained from photometric observations taken by astronomers David Higgins at Hunters Hill Observatory, Australia; by Petr Pravec, Peter Kušnirák, and Lenka Šarounová at Ondřejov Observatory, Czech Republic; and by Štefan Gajdoš, Adrián Galád and Jozef Világi at Modra Observatory, Slovakia. The observations revealed that Bascom is a synchronous binary asteroid that has a moon orbiting its primary every 43.5 hours. Mutual asteroid occultation and eclipsing events with a magnitude between 0.12 and 0.18 suggest that the satellite's diameter is 37±2% of that of Bascom, translating into a mean-diameter of 2.3 kilometers for the minor-planet moon.

Since Bascom's first observation in December 2005, astronomer Peter Pravec has obtained additional lightcurves. They gave a refined rotation period for the primary of 2.74516 to 2.74544 hours with a brightness variation between 0.14 and 0.23 magnitude. These observations also confirmed the presence of the satellite giving a concurring orbital period of 43.51 hours. For an asteroid of its size, Bascom has a relatively fast spin rate, but still above those of fast rotators.

Reader's Guide

The significance of 6084 Bascom lies in its binary nature and its naming after a pioneering female geologist. As a binary Phocaea asteroid, it contributes to the study of asteroid satellite systems, particularly through the detailed photometric observations that revealed its synchronous moon and refined its rotation and orbital periods. The discovery of its satellite in 2005–2006 by an international team of astronomers added to the growing catalog of minor planets with moons, providing data on secondary-to-primary diameter ratios and mutual occultation events. The asteroid's naming honors Florence Bascom (1862–1945), the second woman to earn a Ph.D. in geology in the United States, the first woman hired by the United States Geological Survey, and the first woman elected to the Council of the Geological Society of America. She founded the geology department at Bryn Mawr College, Pennsylvania, where she taught for 33 years. The naming citation was published by the Minor Planet Center on 11 April 1998. Bascom's relatively fast spin rate and its classification as a stony S-type asteroid within the Phocaea family also provide context for understanding the physical properties and orbital dynamics of inner main-belt asteroids.

Did You Know?

• 6084 Bascom was discovered on 12 February 1985 by Carolyn and Eugene Shoemaker at Palomar Observatory.
• It is a binary asteroid with a satellite approximately 2.3 kilometers in diameter, about 37% the size of the primary.
• The asteroid's moon orbits the primary every 43.51 hours, and the primary rotates once every 2.74542 hours.