... The spectrum of the brightest star, our Sun, shows several dark gaps perpendicular to the flow of it’s colours (figure 1). These so called spectral absorption lines where discovered in 1802 by the English scientist William Wollaston. ... Some stars as Pollux show a spectrum similar to that of our sun with strong Ca II and Fe II lines, others as Sirius or Vega show strong absorption lines of hydrogen, others, as Mira show very complicated spectra due to molecular absorption lines (see figure 5). ...

. Authors . Problem . Method . Advises . Contact Analysis of an accuracy of CCD asteroid observations carried out by professional and amateur astronomers . An accuracy estimation of CCD asteroid observations contained in the Minor Planet Center Database and carried out in the years 1999 - 2006 is realized. About 20 millions individual positions of the Numbered and Unnumbered Minor Planets were tested by means of calculations of (O-C) residuals to derive "mean error of a single observation" for more than 400