21028+4551
- Unique Name: 21028+4551BU 1138CE
- RA: 21 02 40.75
- Dec: +45 53 05.1
- Discoverer: BU
- Discoverer Number: 1138
- Components: CE
- First year: 1908
- Last year: 2003
- Observations: 9
- First position angle: 68
- Last position angle: 249
- First separation: 17.1
- Last separation: 23.6
- Mag first component: 7.82
- Mag second component: 12.38
- Spectral type: K2
- Primary proper motion RA: 404
- Primary proper motion DEC: 141
- Secondary proper motion RA: 76
- Secondary proper motion DEC: 22
- Durchmusterung:
- Notes: NL
