The 1970–1984 lunar laser ranging observations in the Crimean Astrophysical Observatory

The Lunar Laser Ranging (LLR) has been the main method of study of the dynamics of the Sun-Earth-Moon system since 1969 to present. Lunar parts of the three modern high-precision ephemerides of the Solar system bodies are based solely on LLR measurements: DE (USA), EPM (Russia), INPOP (France). LLR measurements allow to determine parameters of lunar orbital and rotational motion, as well as some parameters related to terrestrial and lunar tides, and also fundamental relativistic parameters. Those parameters were determined from LLR with high accuracy by different authors. In USSR, LLR measurements were performed in the Crimean Astrophysical Observatory (CrAO) in Nauchny, on the 2.6 m Shajn’s Zenith telescope (ZTSh) with an automated laser ranging system developed by the Russian Lebedev Physical Institute (LPI). Within the time span of 1969–1984, 1400 measurements were obtained. Unlike LLR measurements done in other observatories, they were eventually forgotten and have not made their way into the dataset that is used by scientists worldwide to build lunar ephemerides and conduct other lunar research. The main reason for writing this paper was the discovery by Tryapitsyn, a researcher at the Katziveli station of CrAO, of old printouts containing the 1970–1984 LLR observations made with the ZTSh 2.6 m telescope. Some details were missing from the printouts, which required careful restoration work. In this paper the history of those LLR observations with surrounding historical events is presented, and some details of the analysis these observations are described. Of particular interest is the finding related to the three normal points of Lunokhod-1 ranges obtained in 1974 that allowed Odile Calame to determine the rover’s position with a few kilometers accuracy. Unfortunately, the accuracy was not sufficient for other researchers to confirm and pin down the location of the rover.

Modernization of the telescope ”Sintez” at the CrAO RAS

In 1978, at the Crimean Astrophysical Observatory, the Sintez telescope, was put into operation. The goal of creating of this experimental telescope was to develop technologies for creating segmented optics, as well as a system for controlling the spatial position of mirrors, including the ability to compensate for turbulence in the Earth’s atmosphere thanks to the fast movements of each mirror along two axes. At the beginning of 2018, a decision was made to restore it with the creation of a new optics and control system. In this work, we present a detailed description of the telescope restoration and upgrade process and the first results.

Investigations of space magnetism at the Crimean Astrophysical Observatory. II. Direct spectropolarimetric measurements of stellar magnetic fields

A research on stellar magnetism in Crimea was initiated by pioneer works of A.B. Severny, V.E. Stepanov, and D.N. Rachkovsky. Today, the study of stellar magnetic fields is a key field of research at the Crimean Astrophysical Observatory (CrAO). The 2.6 m Shajn telescope equipped with the echelle spectrograph ESPL, CCD, and Stokesmeter (a circular polarization analyzer) allows us to study the magnetic field of bright stars up to 5m–6m. The Single Line (SL) technique is developed for measuring magnetic fields at CrAO. This technique is based on the calculation of the Zeeman effect in individual spectral lines. A key advantage of the SL technique is its ability to detect local magnetic fields on the surface of stars. Many results in the field of direct measurements of stellar magnetic fields were obtained at CrAO for the first time. In particular, the magnetic field on supergiants (ǫ Gem), as well as on a number of subgiants, giants, and bright giants was first detected. This, and investigations of other authors, confirmed the hypothesis that a magnetic field is generated at all the stages of evolution of late-type stars, including the stage of star formation. The emergence of large magnetic flux tubes at the surface of stars of V-IV-III luminosity classes (61 Cyg A, β Gem, β Aql) was first registered. In subgiants, the magnetic field behavior with the activity cycle was first established for β Aql. Using the long-term Crimean spectroscopic and spectropolarimetric observations of α Lyr, the 22-year variability cycle of the star, supposedly associated with meridional flows, is confirmed. Magnetic field variability with the pulsation period was first detected for different types of pulsating variables: the classical Cepheid β Aql, the low-amplitude β Cep-type variable γ Peg, and others. In this review we cover more than a half-century history of the formation of the Crimean scientific school for high-precision direct measurements of stellar magnetic fields.

Investigations of cosmic magnetism at the Crimean Astrophysical Observatory. I. Magnetic field in the interstellar medium and secondary effects of stellar magnetism

We summarize the main results obtained at the Crimean Astrophysical Observatory for the magnetic field of the interstellar medium and magnetism in the middle- and low-mass stars with the solar-type activity.

Echelle spectrograph at the 2.6 m Shajn telescope

The paper describes the high-resolution echelle spectrograph ESPL developed for the coude focus of the 2.6 m Shajn reflector of the Crimean Astrophysical Observatory. The spectrograph has been regularly operated since 2013. Efficiency of the spectrograph is estimated from observations of stars.

Observation of the exoplanetary transit for Wasp-2

We present observations of the exoplanet transit for the WASP-2 star carried out with the MTM-500 telescope at the Crimean Astrophysical Observatory of the Russian Academy of Sciences. A brief history of the discovery of the exoplanet WASP-2b is considered. The main characteristics are outlined. The observations and a processing procedure are described. Analysis of the obtained results was performed and compared with information from the ETD and NASA Exoplanet Archive databases. The photometry data of the WASP-2 star and the comparison star GSC 0052201406 are given in the Appendix to the article.

Long-term stellar magnetic field study at the Crimean Astrophysical Observatory

The long-term monitoring of magnetic cycles is a key diagnostic in understanding how dynamo generation and amplification of magnetic fields occur in solar-like stars. One of the current key problems is the establishment of the magnetic field behavior during the activity cycles for stars of different ages and evolutionary statuses. We present the experience of using own long-term datasets for study of activity cycles in selected stars at the Crimean Astrophysical Observatory.

Polarimetry of Saturnian satellite Enceladus

We present results of polarimetric observations of Saturn's moon Enceladus carried out from April 14, 2010 to April 13, 2013 in WR spectral band (550-750 nm). We used 2.6-m telescope equipped with a one-channel photoelectric photometer-polarimeter (Crimean Astrophysical Observatory). The measurements were performed at phase angles ranging from 1.65° to 5.71°. The phase-angle dependence of linear polarization of Enceladus was obtained using the results of our observations. Results obtained are discussed in terms of existing models of light scattering by regolith surfaces.