21390+5729
- Unique Name: 21390+5729BU 1143AB
- RA: 21 38 57.61
- Dec: +57 29 20.5
- Discoverer: BU
- Discoverer Number: 1143
- Components: AB
- First year: 1889
- Last year: 2001
- Observations: 4
- First position angle: 324
- Last position angle: 317
- First separation: 1.6
- Last separation: 1.8
- Mag first component: 5.73
- Mag second component: 13.3
- Spectral type: O6f
- Primary proper motion RA: -3
- Primary proper motion DEC: -2
- Secondary proper motion RA:
- Secondary proper motion DEC:
- Durchmusterung: +56 2617
- Notes: N
