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Small Field CCD Astrometry with a Long Focus Reflector Telescope

Calderón, J. H.; Bustos Fierro, I. H.

We discuss the use of the block adjustment method for determining astrometric positions from a mosaic of CCD frames taken with a long focus reflector telescope. The observations cover an area of 25 arcmin × 25 arcmin around the open cluster Rup21. The source of reference positions was the Tycho-2 Catalogue. The internal error in the measured posit…

Quantitative Stellar Spectral Classification. II. Early Type Stars

García, J.; Stock, J.; Stock, M. J. +1 more

The method developed by Stock & Stock (1999) for stars of spectral types A to K to derive absolute magnitudes and intrinsic colors from the equivalent widths of absorption lines in stellar spectra is extended to B-type stars. Spectra of this type of stars for which the Hipparcos catalogue gives parallaxes with an error of less than 20% were ob…