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The Low Dispersion Survey Spectrograph (LDSS)

LDSS allows multi-object spectroscopy of ultra-faint stars and galaxies in the magnitude range 20-23. It has a 12.3' diameter field, and light is fed through a simple but efficient spectrograph onto the IPCS or a CCD. The novel design of LDSS is described by Wynne and Worswick (1988 Observatory 108,161). LDSS uses lenses throughout to maximize efficiency, and has a transmission grating as the dispersion element. The spectrograph was designed to work in the blue, and is optimised for the spectral range 3700-7500Å.

The summary of LDSS properties given below is taken from Colless et al. (1990 MNRAS 244, 408), who also discuss techniques for multi-slit fabrication, acquiring fields at the telescope and data reduction as well as showing examples of spectra taken with the system.

Two grisms are currently available, with dispersions of 165Å/mm and 870Å/mm. LDSS has four modes of operation:

The LEXT software package available on AAO and Starlink computers is used in conjunction with LDSS and has a triple role:

LDSS observers planning to use long slit or multislit mode should contact the LDSS support scientist at AAO well before their run to arrange for masks to be made.



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Next: Multi-object spectroscopy with Up: Spectrographs Previous: The Faint Object



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