21556+2823
- Unique Name: 21556+2823MLB 577BC
- RA: 21 55 34.30
- Dec: +28 23 54.1
- Discoverer: MLB
- Discoverer Number: 577
- Components: BC
- First year: 1928
- Last year: 2010
- Observations: 4
- First position angle: 25
- Last position angle: 20
- First separation: 5.7
- Last separation: 7.0
- Mag first component: 11.1
- Mag second component: 12.6
- Spectral type:
- Primary proper motion RA: -6
- Primary proper motion DEC: -7
- Secondary proper motion RA:
- Secondary proper motion DEC:
- Durchmusterung:
- Notes: