Introduction

The Monash observatory, situated approximately 50 km East-South-East of Melbourne at an elevation of 308 metres, is currently used for differential photometric studies of rapidly rotating, active-chromosphere, cool stars. To expand the range of studies at the observatory, the Physics Department plans to attach a visible-wavelength spectrograph to its 0.46-metre Cassegrainian reflector. This spectrograph is of a crossed Czerny-Turner design that is to operate in the visible wavelength band (3000 Å to 7000 Å). The CCD detector consists of two arrays of pixels with each array containing 2048 elements; each pixel is 13 m wide by 750 m high. It will operate at -50 C. The spectrograph itself has a linear reciprocal dispersion of 40 Å per mm at 5000 Å and will primarily be used to determine the radial velocities of the stars in the Monash observing program.

To enable users of the spectrograph to estimate the precision of radial velocity measurements acquired with the spectrograph, the Monash Spectrograph Simulation Program (MSSP) was created (Marsden 1996). The MSSP is a PC-based software package written in Fortran that allows the user to simulate the effect of the telescope, spectrograph and atmospheric conditions on spectra from various cool star types. The MSSP will also help users to determine the best operational parameters to be used during actual observations with the spectrograph, depending upon the star being studied and the atmospheric conditions during the observation. We outline below how the MSSP simulates the stellar and atmospheric variables involved in observing spectra. We also compare the MSSP's theoretical data with theoretical data from other spectrographs. Also outlined are the expected precisions in the radial velocity measurements to be taken with the spectrograph.

© Copyright Astronomical Society of Australia 1997