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Cassegrain f/13.7
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Sandiford Cassegrain Echelle Spectrometer (CE)
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Bob Franke
(432) 426-4103
bfranke@astro.as.utexas.edu
Users guide for the Sandiford Cass Echelle Guider
Mr. Franke is the McDonald Operations staff member responsible for CE.
The Sandiford Cassegrain Echelle spectrograph is capable of R = 60,000 (5 km/s) resolution for two 27-micron pixels using a
slit of one arcsecond. The spectrograph operates over the wavelength range from 3,700 Å to 11,000 Å with high efficiency.
Wavelength coverage is continuous (no gaps between orders) for wavelengths less than 8,500 Å. Cross dispersion is provided by
an LF5 prism in double pass; total spectral coverage in a single exposure is 1,000 Å to 1,500 Å, depending on central
wavelength, greatest in the red and near infrared, and slit lengths up to 6 arcseconds are permitted. The spectrograph operates very
close to true Littrow, and matches the free spectral range of a 23.2 gr/mm, R2 echelle grating to the long dimension of a
Reticon 1200 ¥ 400 CCD (RA2). A MicroLuminetics
CCD system provides remote guiding but not autoguiding. A new set of slit apertures was
just installed with significant improvement to the stability and reflectivity of the slit assembly.
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