TYCHO photometry calibration and first results
Snijders, M. A. J.; Grewing, M.; Lindegren, L.; van Leeuwen, F.; Grenon, M.; Hog, E.; Scales, D. R.; Andreasen, G. K.; Mauder, H.
Germany, Denmark, Switzerland, United Kingdom, Sweden
Abstract
A description of the data reduction methods used for the Tycho photometry and the software package to implement these methods is presented. Results derived from a preliminary reduction of eight weeks of data employing these methods are reported. A critical discussion of the sources of photometric errors and the expected and achieved photometric accuracy is presented. The distribution of differences between observed and cataloged values of B(T), and differences between the observed and cataloged magnitudes for B(T) are illustrated. Calculated and measured standard deviations for the differences between the standard star magnitudes and the Tycho magnitudes for the vertical V-band data are given.