21519+4221
- Unique Name: 21519+4221HO 172AD
- RA: 21 51 53.07
- Dec: +42 20 40.6
- Discoverer: HO
- Discoverer Number: 172
- Components: AD
- First year: 1875
- Last year: 2003
- Observations: 9
- First position angle: 68
- Last position angle: 61
- First separation: 480.9
- Last separation: 480.9
- Mag first component: 7.93
- Mag second component: 8.63
- Spectral type: G5
- Primary proper motion RA: -175
- Primary proper motion DEC: -306
- Secondary proper motion RA: 39
- Secondary proper motion DEC: 13
- Durchmusterung: +41 4299
- Notes: NU