Locating stars with a multiple-object spectrograph - ARGUS

Abstract

The methods used to locate stars with the Argus, a new multiple-object spectrometer, are described. A number of steps are required to translate user-supplied coordinates into provisional focal-plane positions which will allow the initial placement of the fibers. Advantage of the ability to move the robot probes simultaneously to search for each star in the vicinity of its provisional position is taken. In order for auto-centering to work effectively, it is necessary to develop a procedure for reading the spectrograph CCD rapidly, design a search procedure, and decide on a method of computing an improved position for each fiber. This paper describes how the provisional positions have been determined and how the auto-centering procedure has been implemented in Argus.