Astrophysical supplements to the ASCC‐2.5. II. Membership probabilities in 520 Galactic open cluster sky areas

We present a catalogue (CSOCA) of stars residing in 520 Galactic open cluster sky areas which is the result of the kinematic (proper motion) and photometric member selection of stars listed in the homogeneous All‐sky Compiled Catalogue of 2.5Million Stars (ASCC‐2.5).We describe the structure and contents of the catalogue, the selection procedure applied, and the proper motion and photometric membership constraints adopted. In every cluster area the CSOCA contains the complete list of the ASCC‐2.5 stars regardless of their membership probability. For every star the CSOCA includes accurate J2000 equatorial coordinates, proper motions in the Hipparcos system, BV photometric data in the Johnson system, proper motion and photometric membership probabilities, as well as angular distances from the cluster centers for about 166 000 ASCC‐2.5 stars. If available, trigonometric parallaxes, spectral types, multiplicity and variability flags from the ASCC‐2.5, and radial velocities with their errors from the Catalogue of Radial Velocities of Galactic Stars with high precision Astrometric Data (CRVAD) are also given. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the photographic detection of novae: a specific case in Libra

Comparing ESO GPO astrograph plates taken in September 1990 at La Silla with the Palomar Sky Survey from 1955, a nova was ostensibly discovered at α = 15^h07^m31^s, δ = −1°44′01″.6 (equinox 1950.0). Its magnitudes in 1955 estimated from the Palomar plates are m_B = 16_·^m9 and m_R = 17_·^m. Finally (March 1991), it was identified as a high redshift (z ∼ 0.3) galaxy (Rafanelli, private communication) by spectroscopic means. Radio observations are requested.     

Numerical simulation of colour equations for the uvby system

The results of numerical simulation of colour equations of uvby photometry for filter-defined bandpasses are presented. It is shown that linear transformation equations to the standard system are valid for instrumental systems deviating by no more than 2.5 nm in peak transmission wavelengths. The comparison with the results of observations is satisfying. Im Ergebnis einer numerischen Farbgleichungssimulation im uvby-System wird nachgewiesen, daß für Instrumentensysteme mit Abweichungen der Wellenlängen maximaler Transmission bis zu 2.5 nm gegenüber den Standardwerten eine lineare Transformation möglich ist. Der Vergleich mit Beobachtungsresultaten zeigt eine gute Übereinstimmung.