21203+4921
- Unique Name: 21203+4921BU 839AB
- RA: 21 20 18.92
- Dec: +49 21 08.5
- Discoverer: BU
- Discoverer Number: 839
- Components: AB
- First year: 1881
- Last year: 2003
- Observations: 9
- First position angle: 202
- Last position angle: 207
- First separation: 15.2
- Last separation: 14.5
- Mag first component: 8.26
- Mag second component: 11.9
- Spectral type: M6III
- Primary proper motion RA: 19
- Primary proper motion DEC: 0
- Secondary proper motion RA: 12
- Secondary proper motion DEC: 8
- Durchmusterung: +48 3348
- Notes: