The Ondřejov 2-meter Telescope is used either in the Cassegrain or in the coudé focus; the primary focus is not used. The primary goal is the spectroscopy. Nowadays, the Cassegrain focus is equipped with the fiber-fed echelle spectrograph HEROS owned by the Landessternwarte Heidelberg-Konigstuhl. The coudé focus is equipped with the slit spectrograph. Usually, the slit coudé spectrograph is being used in winter due to the lower sensitivity to the weather condition (seeing).
We present a short tutorial on driving the 2-meter telescope coudé spectrograph and on acquisition of scientific data. We hope that visitors collaborating with stellar department will appreciate this tutorial as an useful cookbook. Although the user interface driving the spectrogtaph and CCD controller is quite comfortable, it is not possible to find or understand all keywords and commands intuitively. Therefore we present this manual containing all necessary commands with descriptions and examples.
We shortly describe the connection between the user-interface and the coudé spectrograph. We present a schematic picture of the internal network connecting the telescope, coudé spectrograph and data server where exposed data are archived.
We present a brief cook-book for the reduction of spectra exposed by the Ondřejov 2-meter telescope coudé spectrograph. For the data reduction, we use standard IRAF packages running on Solaris and Linux. The sequence of commands is given for the typical reduction session together with short explanation and detailed list or parameter settings. The reduction progress is illustrated by example plots.
We present a manual for the reduction of data exposed by the fiber-fed echelle spectrograph HEROS. As the reduction process is really not trivial in fiber echelle spectrography (mainly due to instabiities leading to wave-like patterns in merged spectrum), we remind and discuss the most important influences (if they are known) evoking cited instabilities. Nevertheless, the main accent is put on the reduction process description, list of MIDAS commands, and finally on the description of HEROS arrangement of some MIDAS routines.
The reduction of echelle data (and fiber-fed echelle data especially) is a quite complicated process since there are many unpredictable effects; they may evoke some instabilities in exposed spectra. As consequences of these, there are problems with merging spectral orders - merged continuum exhibits characteristic wave-like patterns. Of course, these structures complicate broad liner measurement (Hα etc.) - thus it is advisable to describe all complications and effects and minimise them, if possible. We have put main accent to the temperature and torsion influences. We will continue with experiments described in this paper; final results and some summary will be published in future.
The reduction of astrophysical spectra is discussed in general. This article is intended as an introduction to following papers where we describe the reduction of data exposed by particular devices (coudé slit spectrograph and Cassegrain fiber-fed echelle spectrograph HEROS).