User's Guide to the Kast Double Spectrograph

Table of Contents

Quick Reference
Hardware Overview
Common Path
Blue Side
Red Side
Detector Characteristics
Kast Controller
Data Taking System
Position Angle
Arc and Flat-field Lamps
Diagonal Mirror
Kast Focus
Telescope Offset
Setup and Observing Hints
Setup Procedures
Observing Hints
Calibration Lamp Spectra
Exposure Time Calculator

Mt. Hamilton Homepage


The Kast Double Spectrograph is used at the cassegrain focus of the Shane 3-m Telescope. It is two separate spectrographs - one optimized for the red, the other for blue - housed in a single structure and having some components in common. Each side offers a selection of dispersive elements for various resolutions and dispersions, and both are also capable of direct imaging over a limited field. Dichroic beamsplitters and separate CCD detectors allow simultaneous observations in red and blue. Both sides are operated from a single interface. A polarimeter is also available for spectropolarimetry observations.

Sept 2015: The Red side CCD is scheduled to be replaced with a new detector in time for the 2016A semester. New detector will be more sensitive, have smaller pixels that will better match the resolution of the blue side detector, as well as be a thick chip so that fringing at longer wavelengths will be minimized.

Aug 2013: The Red side 600/5000 and 600/7500 gratings have been replaced with brand new gratings. Throughput should be higher as the old gratings were somewhat scratched and damaged due to age.

The Kast has been in operation since early 1992. It was designed by Dr. Joseph Miller (UCSC) and built in the Lick Observatory shops. The instrument was made possible by a generous gift from William and Marina Kast.

Much of the material presented here is taken nearly verbatim from Lick Observatory Technical Reports No. 66, The Kast Double Spectrograph, by Joseph Miller and Remington Stone, with updated sections and additional material contributed by the technical staff on Mount Hamilton.

The Kast Spectrograph is available to the University of California astronomical community by subscription.
Follow these links to:

3-m Time Allocation Policy
Observing Time Request Forms

All new users must be checked out by a resident astronomer on their first night. Please request support on your time application.

Please direct questions to a Mount Hamilton support astronomer,