Discovered by E. Helin MPC designation 4209 Briggs Discovered 4 October 1986 Orbits Sun | Discovery date 4 October 1986 Minor planet category main-belt · (outer) Absolute magnitude 10.8 Discoverer Eleanor F. Helin Asteroid group Asteroid belt | |
Named after Geoffrey A. Briggs(space physicist) Alternative names 1986 TG4 · 1969 SB1978 EL8 · 1986 WD51989 CO4 Similar 4015 Wilson–Harrington, Sun, 6489 Golevka, 9969 Braille, 4769 Castalia | ||
4209 Briggs, provisional designation 1986 TG4, is a carbonaceous asteroid from the outer region of the asteroid belt, approximately 28 kilometers in diameter. It was discovered by American astronomer Eleanor Helin at the U.S. Palomar Observatory, California, on 4 October 1986.
The dark C-type asteroid orbits the Sun at a distance of 2.9–3.4 AU once every 5 years and 7 months (2,047 days). Its orbit has an eccentricity of 0.08 and an inclination of 22° with respect to the ecliptic. The first precovery was obtained at El Leoncito in 1969, extending the asteroid's observation arc by 17 years prior to its discovery.
A rotational light-curves of this asteroid was obtained from photometric observations made by American astronomer Brian Warner at the Palmer Divide Observatory in September 2003. The revised light-curve showed a rotation period of 7001122200000000000♠12.22±0.02 hours with a brightness variation of 0.45 in magnitude (U=3-). A second light-curve from a collaboration of Czech, U.S. and Italian observatories published in November 2013, rendered a period of 7001122530000000000♠12.2530±0.0005 hours (U=n/a).
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its NEOWISE mission, the asteroid measures between 25.6 and 31.3 kilometers in diameter and its surface has an albedo in the range of 0.07 to 0.13. The Collaborative Asteroid Lightcurve Link derives an albedo of 0.08 and a diameter of 25.4 kilometer, slightly below the result obtained by IRAS.
The minor planet was named after American space physicist Geoffrey A. Briggs, director of the Solar System Exploration Division at NASA Headquarters during the 1980s. He was instrumental for the formation of the U.S.–Soviet Joint Working Group for Solar System Exploration and became its co-chairman. He was on the imaging teams for the Mariner, Viking and Voyager missions. Briggs continued to promote space-related accomplishments to the public at the Air and Space Museum. Naming citation was published on 27 June 1991 (M.P.C. 18456).