21517+1918
- Unique Name: 21517+1918BU 1506AC
- RA: 21 51 40.18
- Dec: +19 18 25.0
- Discoverer: BU
- Discoverer Number: 1506
- Components: AC
- First year: 1908
- Last year: 2001
- Observations: 4
- First position angle: 121
- Last position angle: 118
- First separation: 26.1
- Last separation: 29.6
- Mag first component: 6.93
- Mag second component: 12.6
- Spectral type: F5IV
- Primary proper motion RA: -35
- Primary proper motion DEC: -8
- Secondary proper motion RA: 11
- Secondary proper motion DEC: -1
- Durchmusterung:
- Notes: