| Epoch |  |
Error |  |
Error |
 |
Ref. |
| 1830.51 | 4.56 | 26.7 | 26.5 | 1 | ||
| 1890.64 | 4.75 | 30.6 | 30.5 | 1 | ||
| 1909.05 | 4.96 | 29.9 | 29.8 | 1 | ||
| 1917.32 | 4.96 | 30.3 | 30.2 | 1 | ||
| 1924.40 | 4.97 | 29.2 | 29.1 | 1 | ||
| 1953.545 | 5.103 | 0.013 | 30.94 | 0.16 | 30.89 | 2 |
| 1960.699 | 5.11 | 0.02 | 30.8 | 0.2 | 30.8 | 3 |
| 1976.784 | 5.02 | 31.3 | 31.3 | 4 | ||
| 1991.25 | 5.279 | 0.004 | 31.53 | 31.52 | 5 | |
| 1991.797 | 5.280 | 0.002 | 31.47 | 0.02 | 31.46 | 6 |
| 1994.747 | 5.29 | 0.20 | 32.05 | 0.78 | 32.05 | 7 |
|
References:
1 Aitken (1932);
2 van Albada-van Dien (1978);
3 van Albada-van Dien (1983);
4 Holden (1977);
5 Hipparcos (ESA 1997) 6 Cuypers & Seggewiss (1999); 7 Popovic & Pavlovic (1997). |