Title Page

Contents

Cepheid Instability Strip Investigation with U–B Intrinsic Colours
N. S. Nikolov, G. R. Ivanov

On the Applicability of Kurucz and Peytremann’s Oscillator Strengths for Stellar Atmosphere Analysis
V. Dobrichev, D. Raikova (in Russian, Summary in English)

Absorption Line Identification of the HR Delphini Premaximum Spectrum
D. Raikova, V. Dobrichev

General Characteristics of the Nova LV Vulpeculae
D. Raikova (in Russian, Summary in English)

An Investigation of the Possibility of Existence of Short Periods in Long-Periodic Ap Stars
K. Panov (in Russian, Summary in English)

Luminosity Function of the Open-Star Cluster NGC 1245
M. Popova, K. Tzvetkova (in Russian, Summary in English)

Proper Motions of Bright Red Giants in Globular Clusters. III. The Globular Cluster M15
N. Spasova (in Russian, Summary in English)

Proper Motions of Bright Red Giants in Globular Clusters. IV. The Globular Cluster M5
N. Spasova, N. Mihnevski (in Russian, Summary in English)

Two-Colour Parallel Observations of Flare Stars in the Region of Cygnus
M. Tsvetkov, L. K. Erastova (in Russian, Summary in English)

UBV-photographic Standards in the Region of the Nebula IC 5070
M. Tsvetkov, K. Tsvetkova (in Russian, Summary in English)

Physical Conditions and Abundances of Some Ions in Diffuse Nebulae
I. Yankulova, G. Petrov, V. Golev (in Russian, Summary in English)

On the Interpretation of the Shane-Wirtanen Counts of Galaxies in 10´×10´ and 1°×1° Squares
G. Dautcourt

On the Differential Rotation of the Solar Filaments
V. Dermendjiev (in Russian, Summary in English)

On the Active Longitudes of the Quiescent Prominences
V. Dermendjiev (in Russian, Summary in English)