SPEFO is a small, yet powerful program used for processing stellar spectra at the Astronomical Institute of the Academy of Sciences of the Czech Republic in Ondrejov. It was originally written in 1990 by Dr. Jiri Horn for processing spectral plates obtained with the 2m telescope of the Ondrejov observatory and scanned at the local five channel microphotometer. Since then the code had been under constant improvement until the sudden death of the author in December 1994. In present days it is used mainly for reduction of data from Ondrejov Reticon detector (1872 pixels, 12 bit A/D), however it can accept data from other instruments too, provided that they are in FITS one-dimensional format.
The code is very small (binary under 350 KB) being written in Turbo Pascal for MS-DOS. An ordinary PC computer with very small hardware demands (PC AT 286, 1MB RAM, 30 MB HD color EGA or VGA) is enough for smooth work. Despite its size the program is very powerful and user friendly as well. The basic data reduction tasks such as derivation of the dispersion function, spectrum rectification, Fourier noise filtering, radial velocity and equivalent width measurement are performed in a quite natural manner and the user can immediately see the change of the data on the screen plot (e.g. the line position is determined in the ``oscilloscopic'' mode by finding the coincidence of the displayed line and its interactively shifted mirrored profile, the continuum level spline is recalculated after fixing of each new point, etc.).
The main output of SPEFO is a table of radial velocities of measured stellar lines (including the atmospheric line correction), their equivalent widths and higher order moments, relative central line intensities and FWHM together with the HPGL plot file. The program can do basic operations on spectra like comparison of two spectra, subtraction, adding, production of differential spectra or the transformation by rotational broadening. SPEFO can also deal with synthetic spectra produced from various model stellar atmospheres allowing their comparison with real data and hence determining the physical parameters (Teff, g, chemical composition) of the star under investigation.