Spectroscopic methods for liquid mirror telescopes

Different methods of spectroscopy with LMTs are described: the objective prism method (a), the parallel (b) and perpendicular (c) long slit methods, the holographic FTS method (d), and the scanning multislit method (e). Advantages and drawbacks of each method are pointed out and estimates of nightly performances are given. Equivalence in the photon-limited regime between all methods offering a full-strip survey (b, c, d) is established, and differences due to CCD read-out mode are discussed. Methods (a) and (e) do not pretend full-strip coverage but may be found more efficient in terms of scientific output. Method (e) is particularly interesting, eliminating all drawbacks of (a) at the cost of increased complexity.