Changes in the Period of Negative Superhumps of Type SU UMa Dwarf Novae. II. NY Her (2017 and 2020)

Astrophysics - Photometric studies of the type SU UMa dwarf nova NY Her were made during 2017 and 2020 at the Crimean Astrophysical Observatory and at the Sanglokh Observatory over a total of 77...     

Connection between the magnetic field strengths and the helium abundance in helium-rich stars

Special Astrophysical Observatory, USSR Academy of Sciences; Crimean Astrophysical Observatory, USSR Academy of Sciences. Translated from Astrofizika, Vol. 33, No. 3, pp. 363–370, November–December, 1990.     

Wide-field plate archives stored in the Ukrainian observatories

The latest version of the Wide-Field Plate Database Catalogue of Wide-Field Plate Archives (April 2008) contains 43 archives stored at some Ukrainian observatories, namely, at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine (Golosiiv, Kyiv), at the Crimean Astrophysical Observatory (Nauchnyi and Simeiz), at the Kyiv, L’viv, and Odesa University Observatories, and at the Mykolaiv Observatory. About 126000 plates were obtained from 1898 to 2005 in the framework of the following observing programmes: Solar System Bodies Observations, Observations of Variable Stars, Investigations of the Emission Nebulae and Connected Stars, Spectral Classification of the Stars and Determination of the Stellar Absorption in the Direction of the Emission Nebulae, Photographic Survey of the Northern Sky (FON), Investigation of the Kinematics and Structure of the Main Meridian Section of our Galaxy (MEGA), Observation of Selected Reference Stars, Artificial Satellites Observations and other. At the moment the basic information on 12609 plates from 13 plate archives of the Main Astronomical Observatory and Crimean Astrophysical Observatory is included into the Wide-Field Plate Database Catalogue of Wide-Field Plate Indexes (Sofia, Bulgaria). The plate digitization is just started with flatbed scanners. Some illustrations of the potential of the Ukrainian plate archives for future reusage are given and some compiled plate catalogues are presented on the basis of data from the Wide-Field Plate Database.     

On the observed carbon underabundance in the atmospheres of B stars

Crimean Astrophysical Observatory. Translated from Astrofizika, Vol. 30, No. 1, pp. 99–110, January–February, 1989.     

On the reality of the observed chemical anomalies of Am stars in the light of their binary nature

Crimean Astrophysical Observatory. Translated from Astrofizika, Vol. 31, No. 3, pp. 519–525, November–December, 1989.     

Element abundances in the atmosphere of the chemically peculiar star β Cr B

Crimean Astrophysical Observatory. Translated from Astrofizika, Vol. 33, No. 2, pp. 251–258, September–October, 1990.     

Stellar spectrophotometer for wavelengths of 3500–8900 Å: I. Optomechanical and control systems

We describe a stellar spectrophotometer designed for the absolute spectrophotometry of stars at wavelengths of 3500–8900 Å with 30 Å resolution. The instrument is mounted on the 80-cm telescope of the Crimean Astrophysical Observatory.     

Observations of extragalactic radio sources at 36 GHz

The observations of 34 extragalactic radio sources with the 22-m Crimean Astrophysical Observatory radio telescope at 36 GHz in 1985–1994 are presented. Intensity variations were detected in 27 objects, which may result from the appearance of new components in their cores.     

Study of radiative energy losses in the moving envelopes of T Tau stars

Crimean Astrophysical Observatory. Translated from Astrofizika, Vol. 32, No. 1, pp. 69–83, January–February, 1990.     

Energy distribution in the Lyman continuum and effective temperatures of the central stars of planetary nebulas

L'vov State University; Crimean Astrophysical Observatory. Translated from Astrofizika, Vol. 32, No. 1, pp. 99–116, January–February, 1990.     

A 23\mathop .\limits^d 2 period in the ultrahigh-energy gamma-ray flux from the Mk 501 active galactic nucleus

Observations at the Crimean Astrophysical Observatory are used to show that the ultrahigh-energy gamma-ray flux from the galaxy Mk 501 varies with a $23\mathop .\limits^d 2$ period. The period was determined by the HEGRA team from the 1997 observations.     

Search for periodicity in light variations of the isolated Herbig Ae-star WW Vulpeculae

Crimean Astrophysical Observatory. Translated from Astrofizika, Vol. 36, No. 1, pp. 61–65, January–February, 1993.     

The mean magnetic field of the Sun: Method of observation and relation to the interplanetary magnetic field

The mean solar magnetic field as measured in integrated light has been observed since 1968. Since 1970 it has been observed both at Hale Observatories and at the Crimean Astrophysical Observatory. The observing procedures at both observatories and their implications for mean field measurements are discussed. A comparison of the two sets of daily observations shows that similar results are obtained at both observatories. A comparison of the mean field with the interplanetary magnetic polarity shows that the IMF sector structure has the same pattern as the mean field polarity.     

Ultrahigh-energy gamma-ray emission from the Geminga pulsar

In 1996–1997, the Geminga pulsar was observed at the Crimean Astrophysical Observatory with a ground-based gamma-ray telescope. An analysis of the observational data suggests that this object is a source of ultrahigh-energy gamma rays. An analysis of the temporal distribution of gamma-ray photons by an epoch-folding technique reveals a periodicity in the gamma-ray emission with a period of 0.237 s.     

Testing of ground-based VLBI stations of radioastron mission: Simeiz-evpatoriya interferometer at 6- and 18-cm wavelengths

As part of the scientific cooperation between Ukraine and Russia, a series of studies on the preparation of the ground segment of the RadioAstron mission has been carried out. A scientific program of measurements to be performed using the 22-m RT-22 radio telescope (Crimean Astrophysical Observatory) has been prepared. A substantial part of this program is the study of compact structures in extragalactic sources. Ground-based VLBI test experiments at 6 and 18 cm intended for testing a model of the ground segments of the RadioAstron mission have been carried out at RT-22 of the Crimean Astrophysical Observatory in Simeiz and RT-70 (P-2500) in Evpatoriya. The processing of the data recorded by each antenna resulted in obtaining and calibrating responses of cross-correlation functions using the ASC LPI correlator. The results of the experiment demonstrate the readiness of RT-22 and RT-70 to participate in the ground-space radio interferometer sessions in the RadioAstron mission.     

Dust around young stars. Model of envelope of the Ae Herbig star WW Vul

Leningrad State University; Crimean Astrophysical Observatory. Translated from Astrofizika, Vol. 34, No. 2, pp. 181–198, March–April, 1991.     

Formation of emission lines of hydrogen,calcium, and magnesium in expanding envelopes of T Tau stars

Crimean Astrophysical Observatory. Translated from Astrofizika, Vol. 32, No. 3, pp. 383–404, May–June, 1990.     

Searching for the host galaxy of GRB 920925C

GRB 920925C is probably the first cosmic gamma-ray burst with an optical afterglow detected from archival data. We present the results of our observations with the Shajn mirror telescope of the Crimean Astrophysical Observatory aimed at searching for the host galaxy at the afterglow location; we have determined the boundaries of distances to the possible host galaxy.     

Five hertz—A characteristic frequency of neutron stars?

Crimean Astrophysical Observatory. Translated from Astrofizika, Vol. 30, No. 2, pp. 362–370, March–April, 1989.     

Initial flare phase of UV Ceti stars

Crimean Astrophysical Observatory; Leningrad State University. Translated from Astrofizika, Vol. 28, No. 2, pp. 355–362, March–April, 1988.