| Reference | Years | Comments | ||
| Shapley (1916) | 1899-1914(1) | 5540 | 40 |
|
| Balász & Detre (1943) | 1935-1941 | 2188 | 41 |
|
| Struve & Blaauw (1948) | 1947 | 42 | 42 |
|
| Walraven (1949) | 1947 | 201 | 41(5) | |
| Fringant (1961)(1) | 1949-1956 | 2500+ | 40.8 (1),(6) |
|
| Preston et al. (1965) | 1961-1964 | 1026 (Ph.), 855 (Sp.)(7) | 40.8(8) | |
| Detre & Szeidl (1973) | 1899-1972 | 25000+ | 41(9) | |
| Belserene (1999) | 1993-1994 | 477 | 39.2 | |
| Smith et al. (2003) | 1996 | 77 | 40 ( |
|
| This paper | 2003-2004 | 421 | 38.8 |
|
(1) Result also based on older data sets by other observers. (2) Derived from the variations in time of the median magnitude. Also mention of a longer cycle of 16.5 years. (3) The authors write that the light curve variations of RR Lyr can most easily be discribed by a superposition of two pulsations with the period P0=0.567 d and P1=0.559 d. (4) From the variation in the radial velocity curve. (5) An additional period is mentioned, about three times longer than (6) The author mentions four periods of RR Lyr: P0=0.5668 d, (7) Simultaneous spectroscopic and photometric data. (8) Reference to Fringant's (1961) elements. (9) First mention of RR Lyr's "4-year cycle''. The authors report that during one and the same "4-year cycle'' |