| Identification Data |
| Common Name | |
| Constellation | Cygnus |
| Star Name | 21eta Cyg |
| Skymap Number | 19560069 |
| Henry Draper (HD) Number | 188947 |
| Harvard Revised (HR) Number | 7615 |
| SAO Number | 69116 |
| Durchmusterung (DM) Number | BD+34 3798 |
Washington Double Stars (WDS) Number
| 19563+3505
|
| Positional Data |
| Position and Proper Motion (PPM) Number | 83853 |
| Right Ascension (RA) J2000 | 19h 56m 18.371s |
| Declination (Dec) J2000 | +35° 5' 0.325" |
| Position Uncertainty | 0.0054s |
| Proper Motion in RA (J2000)/cos(Dec) | -0.00277 |
| Proper Motion in Dec (J2000) | -0.027666 |
| Radial Velocity | -026.5km s-1 |
| Trigonometric Parallax | +0.02340s |
| Trigonometric Parallax Uncertainty | 0.00054s |
| GCI Unit Vector in X (J2000) | 0.397683 |
| GCI Unit Vector in Y (J2000) | -0.715185 |
| GCI Unit Vector in Z (J2000) | 0.574769 |
| Galactic Longitude | 71.02° |
Galactic Latitude
| 3.36°
|
| Observational Data |
| Observed Visual Magnitude (V) | 3.90 |
| Derived Visual Magnitude | |
| Derived Visual Magnitude or Observed Visual Magnitude Uncertainty | 0.002 |
| Observed B Magnitude | 4.92 |
| Observed B-V Colour | +1.017 |
| Observed B Magnitude or (B-V) Magnitude Uncertainty | 0.003 |
| Observed U Magnitude | |
| Observed U-B Colour | |
| Observed U Magnitude or (U-B) Magnitude Uncertainty | |
| Observed Photovisual Magnitude | 4.0 |
| Observed Photographic Magnitude | |
| Morgan Keenan (MK) Spectral Type | K0III |
| One-Dimensional Spectral Class | K0 |
| Position Angle | 208 |
| Year of Observation | 1958. AD |
