The High Altitude Observatory Stokes Polarimeter

The measurement of solar magnetic fields

“…(i) Spectrographs (Hale 1908, Thiessen 1952, Kiepenheuer 1953, Babcock 1953, Leighton 1959, Stepanov and Severny 1962, Rayrole 1967, Bruckner 1968, Wiehr 1969, Deubner and Liedler 1969, Mayfield et al 1969, Dunn 1971, Livingston and Harvey 1971a, b, Title and Andelin 1971, Wittmann 1973, Howard 1974, Baur et al 1974, Dunn et al 1974, Livingston et al 1976, Lebedev and Grigorjev 1976. They have been by far the most widely used instruments, are very flexible and are simple to handle.…”