21045+2457
- Unique Name: 21045+2457SLE 520AB
- RA: 21 04 29.23
- Dec: +24 57 03.5
- Discoverer: SLE
- Discoverer Number: 520
- Components: AB
- First year: 1891
- Last year: 2008
- Observations: 7
- First position angle: 346
- Last position angle: 347
- First separation: 34.0
- Last separation: 34.2
- Mag first component: 9.73
- Mag second component: 11.62
- Spectral type: K2
- Primary proper motion RA: 2
- Primary proper motion DEC: 5
- Secondary proper motion RA: -2
- Secondary proper motion DEC: 5
- Durchmusterung: +24 4313
- Notes: