|Discovered by K. Reinmuth|
MPC designation 1009 Sirene
Minor planet category Mars-crosser
Discovered 31 October 1923
Discoverer Karl Wilhelm Reinmuth
Asteroid group Mars-crosser asteroid
|Discovery date 31 October 1923|
Alternative names 1923 PE
Observation arc 91.64 yr (33473 days)
Named after Siren
|Discovery site Landessternwarte Heidelberg-Königstuhl|
Similar 1056 Azalea, 1002 Olbersia, 132 Aethra, 114 Kassandra, 1001 Gaussia
1009 Sirene is a Mars-crosser asteroid. It was discovered by Karl Wilhelm Reinmuth on October 31, 1923, and observed for 4 months. Its provisional designation was 1923 PE and it was named after the mythological Sirens. It became a lost asteroid until it was recovered in 1982 from exposures on the 48-inch (120 cm) Schmidt at Palomar Observatory.
Sirene's semi-major axis is 2.62 AU, well beyond that of Mars, but its highly eccentric orbit crosses Mars', allowing close approaches of the planet. On 8 June 1949 the asteroid passed 0.049 AU (7,300,000 km; 4,600,000 mi) from Mars. With an absolute magnitude of 13.9, the asteroid is about 5–10 km in diameter.