Introduction

The TAURUS Tunable Filter (TTF) is a new facility at the AAT that allows fully monochromatic narrowband imaging over an arbitrary bandpass (6 - 60 Å FWHM) at R and I-bands. This instrument combines the flexibility of an ordinary Fabry-Perot interference filter to scan in wavelength with the widefield monochromaticity of fixed narrowband interference filters. Unlike an ordinary Fabry-Perot however, the TTF works at orders low enough that a single interference ring covers almost all of the detector area.

The strength of the TTF is its unique ability to detect faint emission-line sources over a useful area on the sky. These are emission-line sources that would otherwise be lost within background sky noise on broadband images. We intend to exploit this facility as a means of probing for faint field and cluster emission-line galaxies (ELGs) at cosmologically interesting distances.

© Copyright Astronomical Society of Australia 1997