|Discovered by||E. F. Helin|
|Discovery site||Palomar Obs.|
|Discovery date||6 September 1989|
|R. Stephen Saunders|
|NEO · Amor |
|Orbital characteristics |
|Epoch 4 September 2017 (JD 2458000.5)|
|Uncertainty parameter 0|
|Observation arc||34.63 yr (12,647 days)|
|3.50 yr (1,278 days)|
|0° 16m 53.76s / day|
|Earth MOID||0.1908 AU · 74.3 LD|
|Dimensions||0.467 km (derived)|
|SMASS = Sq  · S |
|18.0 · 18.45±0.2 (R)[a] · 18.8 · 19.02±0.112|
The asteroid was discovered on 6 September 1989, by American astronomer Eleanor Helin at Palomar Observatory in California, United States. It was named for JPL-project scientist R. Stephen Saunders.
A first precovery was taken at the Australian Siding Spring Observatory in 1982, extending the body's observation arc by 7 years prior to its official discovery at Palomar. It has a minimum orbital intersection distance with Earth of 0.1908 AU (28,500,000 km), which corresponds to 74.3 lunar distances.
In the SMASS classification, Saunders is a Sq-type, which transitions from the common S-type to the Q-type asteroids. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and derives a diameter of 467 meters, based on an absolute magnitude of 19.02.
In October 1989, the first photometric observations of Saunders were made with the ESO 1-metre telescope at La Silla in Chile. It gave a rotation period of 6 hours with a brightness variation of 0.3 magnitude (U=2). Another rotational lightcurve was obtained by Czech astronomer Petr Pravec at Ondřejov Observatory in August 2003, giving a period of 6.423±0.004 and an amplitude of 0.2 magnitude (U=n.a.).[a]
This minor planet was named in honor of JPL-project scientist R. Stephen Saunders (born 1940), director of the RPIF and head scientist of the Solar System Exploration Office. He worked on the Mars Surveyor 2001/03 program and on the Magellan spacecraft, that visited and mapped Venus in 1990. The official naming citation was published by the Minor Planet Center on 26 July 2000 (M.P.C. 41028).