(21531) Billcollin Main-belt Asteroid
Discovered on 20 July 1998 by ODAS at Caussols.
Bill Collin (b. 1947) made important contributions to the design and manufacture of the Auxilliary Telescope System of the European Southern Observatory's Very Large Telescope.Naming citation (20051215/MPCPages.arc), IAU / Minor Planet Center, via NASA/JPL
Where Billcollin is today
Seen from above the solar system on 2026-10-14: Billcollin is 2.91 au from the Sun and 2.11 au from Earth. Computed from JPL's orbital elements.
Facts
| Number | 21531 |
| Provisional designation | 1998 OS |
| Orbit class | Main-belt Asteroid |
| Diameter | 6.28 km (#8,532 largest of 17,440 named asteroids with a measured size) |
| Albedo | 0.0560 |
| Absolute magnitude (H) | 14.69 |
| Orbital period | 4.59 years |
| Semi-major axis | 2.76 au |
| Perihelion – aphelion | 2.57 – 2.96 au |
| Eccentricity | 0.0708 |
| Inclination | 6.10° |
| Closest distance between its orbit and Earth's (MOID) | 1.59 au |
Data: NASA/JPL Small-Body Database and the IAU Minor Planet Center.
Also named after someone called Bill
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- (7784) Watterson
- (15964) Billgray
- (19695) Billnye
- (20084) Buckmaster
- (24495) Degroff
- (24959) Zielenbach
- (27284) Billdunbar
- (48643) Allen-Beach
- (79896) Billhaley
- (80808) Billmason
- (95852) Leatherbarrow
All asteroids named after someone called Bill
Also discovered on 20 July 1998
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- (13701) Roquebrune
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