Automated analysis of slitless spectra. I - Software, algorithms, and calibrations

Abstract

Automated software was developed to process slitless spectra. The software automatically separates stars from extended objects and quasars from stars. Among the many parameters output by the program, are narrow-band and broad-band photometric indices, spectra discontinuities, and emission and absorption lines. The lines are found with respect to an automatic continuum fit. All of these quantities are given with associated errors and signal-to-noise ratios. A considerable effort was made to calibrate the data and to understand systematic effects. An attempt was made to give all relevant quantities in terms of signal-to-noise ratios. Extensive use was made of computer simulations to understand the algorithms and check systematic errors. The program does not depend on the measurement of direct plates. The paper discusses in detail the techniques and algorithms used. The software can be used to study stars, galaxies, and quasars.