Three Periods in Asteroid 4197 Brightness Variations

In 1996, photometric observations of the near-Earth asteroid NEA 4197 (1982 TA) were performed at the Crimean Astrophysical Observatory. More than 2000 brightness measurements in the V band were made. The harmonic data analysis at a fairly high significance level revealed two close periods, P ₁= 3^h _.5372 ± 0^h _.0005 (amplitude 0 ^m _.4) and P ₂= 4^h _.367 ± 0^h _.001 (amplitude 0 ^m _.2). The third period, P ₃= 20^h _.26 ± 0^h _.05 (amplitude about 0 ^m _.15), was found at a lower significance level. The conclusion was drawn that the asteroid is a binary system. Its components rotate with the periods P ₁and P ₂, and P ₃is probably related to the orbital motion of the components. Assuming that the diameters of both components are equal to 2 km, the orbital radius equals 4.4 km.     

The existence of quasi-periodic oscillations with periods from a minute up to some hours in the solar radio emission at λ = 3 cm

Quasi-periodic components (QPC) of the solar radio emission may give information about the wave (oscillation) motions in the whole depth of the solar atmosphere. Investigations of quasi-periodic components (QPC) of the radio emission fluctuations give contradictory and often doubtful results. Special care must be taken when registering fluctuations and peculiar attention have to be paid to the correctness of the mathematical processing. Results of investigation are given of the solar radio emission fluctuations carried out by 3 cm radio telescopes 1300 km spaced. The reality of QPC existence with the periods from a minute up to some hours is shown. QPC with the periods 1–10 min change during 2 hours. Some possibilities of the origin of oscillations observed are considered.     

On the Family of the Binary Asteroid 423 Diotima

We identified the family of the binary asteroid 423 Diotima consisting of 411 members in the phase space of orbital elements—semimajor axes a (or mean motions n), eccentricities e, and inclinations i—by using an electronic version of the ephemerides of minor planets EMP-2003 containing osculating orbital elements for 34992 asteroids of the main belt. The 9/4 resonance with Jupiter clearly separates the family of 423 Diotima from the family of Eos, which, according to EMP for 2003, contains 1204 asteroids.     

Photometric and Colorimetric Observations of Asteroid 423 Diotima and Their Analysis

Series of photometric and colorimetric observations of the Main-Belt asteroid 423 Diotima during its five oppositions were obtained at the Crimean Astrophysical Observatory. It was concluded, based on the results of a frequency analysis of the V-band photometry obtained in 1990, that the asteroid is a binary system: the rotation period of the primary component is equal to 4_. ^h56, and the period of rotation and the orbital period of the satellite are equal to 14_. ^h90. An analysis of simultaneous BV and BVR observations made in 1993 and 1998–1999 yielded a rotation period of 4_. ^h54 ± 0_. ^h01 for the primary component. An analysis of the sets of V-band observations of the asteroid made from 1982 through 2000 allowed us to find the period of forced precession, which was equal to 113^d (or 226^d). It was suggested that the axis of the primary component of the binary asteroid precesses and the large amplitude of brightness variations (about 1 ^m ) is due to its lenticular shape.     

The Surface Structure of the M-Type Asteroid 21 Lutetia: Spectral and Frequency Analysis

A preliminary study of the surface of the asteroid 21 Lutetia with ground-based methods is of significant importance, because this object is included into the Rosetta space mission schedule. From August 31 to November 20, 2000, about 50 spectra of Lutetia and the same number of spectra of the solar analog HD10307 (G2V) and regional standards were obtained with a resolution of 4 and 3 nm at the MTM-500 telescope television system of the Crimean astrophysical observatory. From these data, the synthetic magnitudes of the asteroid in the BRV color system have been obtained, the reflected light fluxes have been determined in absolute units, and its reflectance spectra have been calculated for a range of 370–740 nm. In addition, from the asteroid reflectance spectra obtained at different rotation phases, the values of the equivalent width of the most intensive absorption band centered at 430–440 nm and attributed to hydrosilicates of the serpentine type have been calculated. A frequency analysis of the values V(1, 0) confirmed the rotation period of Lutetia 0.^d3405 (8.^h172) and showed a two-humped light curve with a maximal amplitude of 0.^m25. The color indices B-V and V-R showed no noticeable variations with this period. A frequency analysis of the equivalent widths of the absorption band of hydrosilicates near 430–440 nm points to the presence of many significant frequencies, mainly from 15 to 20 c/d (c/d is the number of cycles per day), which can be caused by a heterogeneous distribution of hydrated material on the surface of Lutetia. The sizes of these heterogeneities (or spots) on the asteroid surface have been estimated at 3–5 to 70 km with the most frequent value between 30 and 40 km.     

Spectrophotometric observations of the nuclei of the seyfert galaxies NGC 4051, NGC 7469, and NGC 1275

A digital television complex, equipped with an original slitless spectrograph with transpaarent diffraction gratings, and operating on the 0.5-meter telescope of the Crimean Astrophysical Observatory, was used for spectrophotometric observations of the nuclei of Seyfert galaxies. The absolute energy distributions in the spectra of the nuclei of the Seyfert galaxies NGC 4501, NGC 7469, and NGC 1275 in the wavelength range 4000–7000 Å were obtained. Synthetic stellar magnitudes in the V band were calculated. The apparatus can be used to investigate the spectral variability of emission from the nuclei of Seyfert galaxies on a time scale of tens of minutes or more.Translated from Astrofizika, Vol. 39, No. 1, pp. 101–110, January–March, 1996.