21105+4742
- Unique Name: 21105+4742BU 159AD
- RA: 21 10 30.96
- Dec: +47 41 32.0
- Discoverer: BU
- Discoverer Number: 159
- Components: AD
- First year: 1911
- Last year: 2012
- Observations: 6
- First position angle: 147
- Last position angle: 145
- First separation: 14.5
- Last separation: 14.0
- Mag first component: 6.55
- Mag second component: 13.5
- Spectral type: B6IV
- Primary proper motion RA: -4
- Primary proper motion DEC: -4
- Secondary proper motion RA:
- Secondary proper motion DEC:
- Durchmusterung:
- Notes: N
