On possible binarity of Leatitia asteroid 39

The 39 Laetitia asteroid was observed by the digital television complex at the Crimean Astrophysical Observatory in 2000 in three spectral bands close to B, V and R simultaneously. An analysis of the variations in the absolute magnitude shows that there is a known period of rotation P = 0.^d214093. In variations of color indices B-V and V-R, this period is absent. Frequency analysis of color indices B-V and V-R makes it possible to reveal the true periods of rotation for components as follows: P ₁ = 0.^d237 and P ₂ = 0.^d177. The theoretical and observed period of librations agrees in value. Based on the two detected periods of rotation for asteroid components according to color indices B-V and V-R, a period of the libration of the satellite according to integral magnitude, we conclude that this asteroid is a binary one.     

Evidence of the complex structure of asteroid 21 Lutetia

We discuss the results of the analysis of three sets of observations of asteroid 21 Lutetia—spectrophotometry, simultaneous BVR photometry, and spectrometry—which show that the asteroid is not a monolithic body. The frequency analysis of the B-V and V-R color indices and the V values, which were obtained from simultaneous BVR measurements in 2004 and calculated from the spectrophotometric observations performed in 2000 (the synthetic values and the color indices), allowed us to demonstrate that the known rotation period of 8.^h172 of the asteroid does not exist at all. At a rather high confidence level, six new periods were found: 2.^h0, 2.^h93, 16.^h8, 1.^d25, 3.^d25, and 60^d. During spectral observations with a 1.25-m telescope at the southern laboratory of the Sternberg Astronomical Institute in Nauchnyi (Crimea) in 2004, the spectra of two components spaced 2.8″ apart were registered. In the short-wavelength spectral range, quick variations of the reflectance of the components were observed. They show the changes in their spectral types from S to C. The analysis of the synthetic values of the color indices determined from the spectrophotometric observations in 2000 confirmed the presence of quick spectral variations. We conclude that asteroid 21 Lutetia is a complex satellite system. This statement is confirmed by the analysis of data published in different sources.     

Lightcurves and phase relation of asteroid 324 Bamberga

A worldwide photometric investigation of the asteroid 324 Bamberga was conducted during the period September–November 1978. The full-cycle lightcurve shows two maxima and two minima with a maximum amplitude of 0.075 mag; the rotation period was found to be P_syn = 29.^h42 ± 0.^h01. A linear least-squares solution of the phase relation gives β_y = (0.334 ± 0.001) mag/degree and V₀ (1, 0) = (7.17 ± 0.01) mag. The color indices measured are B-V = 0.69, U-B=0.36, in agreement with the C taxonomic type given for 324 Bamberga. The very long period indicates 324 Bamberga is an unusual object among asteroids with diameters greater than 200 km.     

The lightcurve and phase relation of the asteroid 133 Cyrene

The asteroid 133 Cyrene was observed photometrically on 17 nights during oppositions in 1979 and 1980. The synodic period of rotation was found to be 12.^h708 ± 0.^h001 with an amplitude of ～0.^m30 during both oppositions. At large phase angles, the phase relation is quite ordinary (β_v ≈ 0.025 mag/degree); however, the low phase angle observations reveal a dramatic opposition brightening, ～0.2 mag/degree near zero phase angle. The absolute magnitude, V(1,0), extrapolated with the above linear phase coefficient, is 8.40. The following color indicates were also measured: B- V = 0.90, U-B = 0.51.     

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.     

Photoelectric lightcurves of asteroids 42 Isis, 45 Eugenia, 56 Melete, 103 Hera, 532 Herculina,and 558 Carmen

Photoelectric observations of six asteroids are presented. The following synodic periods of rotation and amplitudes of variation are reported: 42 Isis, P = 13^h.59, Δm = 0.32; 45 Eugenia, P = 5^h.70, Δm = 0.30; 56 Melete, P = 13^h.7 or 19^h.0, Δm = 0.06; 532 Herculina, P = 9^h.408, Δm = 0.15; 558 Carmen, P ≈ 10^h, Δm ≈ 0.25. The asteroid 103 Hera exhibited no periodic variation in excess of about 0.03 magnitude. The period found for 532 Herculina is one half that previously reported by other observers.     

Physical studies of asteroids IX: The light curve of the M asteroid 77 Frigga

The results of photoelectricUBV observations of asteroid 77 Frigga during the 1982 opposition are presented. From eight nights of observations at phase angles smaller than 2 _o ^. 8 a synodic period of 0 _d ^. 3755±0 _d ^. 0006 is derived. The light curve appears very symmetric with two maxima per period and an amplitude of 0 _m ^. 19. The primary maximum corresponds toV(0^o)=8 _m ^. 58, and the colour indices are:B–V = 0 _. ^m 738 ± 0 _. ^m 003 andU–B = 0 _. ^m 200 ± 0 _. ^m 002.     

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.     

Lightcurves and phase relations of the asteroids 82 alkmene and 444 Gyptis

The asteroids 82 Alkmene and 444 Gyptis were observed photoelectrically at Table Mountain Observatory and at Torino Observatory during their 1979 oppositions. The rotation periods and amplitudes of variation observed were, for 82: P_syn = 12.^h999, Δm = 0.55; and for 444: P_syn = 6.^h214, Δm = 0.15. The phase relation of 82 Alkmene can be well fit to the theory of K. Lumme and E. Bowell (Astron. J. (1981), 86, 1705). It showed a probable decrease in brightness of ～0.04 mag from 1 month before opposition to 2 months after opposition, which can be attributed to the changing viewing aspect coupled with polar flattering of the asteroid. The phase relation of 444 Gyptis is poorly fit by the Lumme and Bowell theory when only Q and V(0η) are treated as variables. A good fit can be obtained by adjusting some of the other parameters of their theory, but the physical interpretation is ambiguous.     

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.     

Photometric observations and modelling of the asteroid 85 Io in conjunction with data from an occultation event during the 1995–96 apparition

The asteroid 85 Io has been observed using CCD and photoelectric photometry on 18 nights during its 1995–96 and 1997 apparitions. We present the observed lightcurves, determined colour indices and modelling of the asteroid spin vector and shape. The colour indices (U-B = 0.35±0.02, B-V = 0.66±0.02, V-R = 0.34±0.02, R-I = 0.36±0.02) are as expected for a C-type asteroid. The allowed spin vector solutions have the pole co-ordinates λ₀ = 285±4°, β₀ = −52±9° or λ₀ = 108±10°, β₀ = −46±10° and λ₀ = 290±10°, β₀ = −16±10° with a retrograde sense of rotation and a sidereal period P_sid = 0^d.286463±0^d.000001. During the 1995–96 apparition the International Occultation Time Association (IOTA) observed an occultation event by 85 Io. The observations and modelling presented here were analysed together with the occultation data to develop improved constraints on the size of the asteroid. The derived value of 164 km is about 5% larger than the IRAS diameter. © 1999 Elsevier Science Ltd. All rights reserved.     

Results of Complex Observations of Asteroid (596) Scheila at the Sanglokh International Astronomical Observatory

Results of astrometric and BVRI photometric observations of the active asteroid (596) Scheila are presented. The observations were carried out at the Zeiss-1000 telescope of the Sanglokh International Astronomical Observatory of the Institute of Astrophysics of the Academy of Sciences of the Republic of Tajikistan on June 16?17 and from July 30 to August 1, 2017. The coordinates of the object and its orbit were determined; and the apparent brightness in four filters, the absolute brightness in the V and R filters, and the color indices were obtained. The light curves suggest that no substantial changes in the asteroid’s brightness occurred during the observations. The absolute brightness of the asteroid in the V and R filters was (9.1 ± 0.05)^m and (8.8 ± 0.03)^m, respectively. The mean value of the asteroid diameter was (119 ± 2) km. The mean values of the color indices (B?V = (0.72 ± 0.05)^m, V?R = (0.29 ± 0.03)^m, and R?I = (0.31 ± 0.03)^m) agree well with the values for asteroids of the P- and D-types and its averages. The rotation period of the asteroid estimated from photometric observations was 16.1 ± 0.2 h. The analysis of the data has shown that the asteroid continues to exhibit the same values of absolute brightness and other characteristics as those before the collision with a small body in December 2010, though the latter resulted in the outburst event and cometary activity of the asteroid. Most likely, the collision of asteroid (596) Scheila with a small body did not lead to catastrophic changes in the surface of the asteroid or to its compete break-up.     

Five-color photoelectric photometry of asteroid 433 Eros

Five-color photoelectric lightcurves of asteroid 433 Eros were obtained on 9 nights during the 1974/75 apparition. Although color differences due to changing solar phase angle were detected, color differences during a single rotation of Eros are less than 1%. Amplitudes of up to 1^m.44 were measured, and there are indications that three reversals in the relative depths of the two minima occured between late December 1974 and late January 1975. The absolute visual magnitude at primary maximum, corrected to zero phase and to one AU from Earth and Sun, is about V₀(1,0) = 10^m.8.     

VR c photometry of dwarf cepheids (I)

In this paper, we present VRc photometric observations of four dwarf cepheids: YZ Boo (P = 0 _. ^d 104, V = 0 _. ^m 5), AD CMi (P = 0 _. ^d 123, V = 0 _. ^m 5), XX Cyg (P = 0 _. ^d 135, V = 0 _. ^m 5), EH Lib (P = 0 _. ^d 088, V = 0 _. ^m 7). The light curves were obtained at West Mountain Observatory, Provo, Utah on 14 nights from 1983 through 1986 and contain 589 data points in each of theV andR bands in the Cousin photometric system. A detailed study of these stars, based on the present light curves, will be published separately.     

V792 Her=HD 155638: A totally eclipsing RS CVn binary

Photometry of HD 155638=V792 Her has been analyzed to determine the elements of this totally eclipsing RS CVn binary. The light variation outside eclipse was found to have a period of 27^d.07±0^d.07, which is slightly different from the 27^d.5384±0^d.0045 orbital period. Analysis of the eclipses was achieved by a modification of the Russell-Merrill technique. With the aid of radial velocity measures, absolute elements were obtained for the hot and cool stars, respectively;R _h=2.58R ,R _c=12.28R ,M _h=1.40M ,M _c=1.46M ,i=80^o.61 and velocity semi-amplitudesK _c=48.36 km s^–1±0.79 km s^–1, andK _h=50.50 km s^–1±0.33 km s^–1. The apparent magnitudes areV _h=9 ^m .73 andV _c=8 ^m .48. The distance to HD 155638 was estimated to be 310 parsecs.     

Lightcurves and the axis of rotation of 433 Eros

Ten lightcurves and UBV photometry of 433 Eros were obtained between August 1972 and May 1975. The absolute magnitude of the lightcurve maximum is 10.75 and the phase coefficient is 0.025 mag/deg. There may be a small difference in B-V color between the northern and southern hemispheres. The pole of the axis of rotation is directed toward λ₀ = 16°, β₀ = 12°, ecliptic longitude and latitude, respectively, and the rotation is direct with a sidereal period of 0.^d219599 or 5^h16^m13^s4 ± 0.^s2. The dimensions derived from the polarimetric albedo and the lightcurve amplitudes are 12km × 12km × 31km for a smooth cylinder with hemispherical ends.     

Physical observations of (5145) Pholus

We present physical measurements of the newly discovered asteroid, (5145) Pholus, based on seven nights of photometric observations. These observations determine an unambiguous lightcurve period of 9.9825 ± 0.0040 hr with a peak-to-peak amplitude of 0.15 mag. We also report a rotationally independent color of (V − R) = 0.810 ± 0.006 (Kron-Cousins R). The standard IAU two parameter fit versus solar phase angle yields H_V = 7.645 ± 0.011 and G_V = 0.16 ± 0.08. Except for its color and orbit, (5145) Pholus exhibits normal asteroidal properties.     

Short-term variations of some UV-ceti type flare stars

Sinusoidal variations in bothV - andB-bands were detected in some flare stars of the UV Ceti type outside of flares. This detection has confirmed the light variation detection in Johnson'sV -band in EV Lac at quiet-state luminosity by Pettersen (1980) with a cyclic period equals about 4 _. ^d 378 and an amplitude of about 0 _. ^m 07. An interpretation of these short cyclic periods is that they are due to intensity modulations from a photospheric spot group as a result of stellar equatorial rotations. A short period of 14 days with an amplitude of 0 _. ^m 099 was detected inB-band in AD Leo. For the two flare stars, BD+55° 1823 and DO Cep in bothV- andB-bands, cyclic periods of more than 3 days and less than 17 days with amplitudes more than 0 _. ^m 090 and less than 0 _. ^m 250 have been registered. A significant contribution has been found in the flare star EV Lac in bothV- andB-bands at its quiescent-state luminosity where the detected cyclic periods are agreed with that which was detected by Pettersen (1980) in the same flare star in Johnson'sV-band, about 4 days. Furthermore, we found the same cyclic period in the colour index,B - V (about 4 days) which strengthens starspot phenomenon. This colour index period could not be detected by Pettersen (1980).     

Photometric and spectroscopic study of the supergiant with an infrared excess V1027 Cygni

We present the results of our UBV and JHKLM photometry for the semiregular pulsating variable V1027 Cyg, a supergiant with an infrared excess, over the period from 1997 to 2015 (UBV) and in 2009–2015 (JHKLM). Together with the new data, we analyze the photometric observations of V1027 Cyg that we have obtained and published previously. Our search for a periodicity in the UBV brightness variations has led to several periods from P = 212^d to 320^d in different time intervals. We have found the period P = 237^d based on our infrared photometry. The variability amplitude, the lightcurve shape, and themagnitude of V1027 Cyg atmaximum light change noticeably from cycle to cycle. The deepest minimum was observed in 2011, when the amplitudes of brightness variations in the star reached the following values: ΔU = 1 _. ^m 28, ΔB = 1 _. ^m 10, ΔV = 1 _. ^m 05, ΔJ = 0 _. ^m 30, ΔH = 0 _. ^m 35, ΔK = 0 _. ^m 32, ΔL = 0 _. ^m 26, and ΔM = 0 _. ^m 10. An ambiguous correlation of the B ? V and U ? B colors with the brightness has been revealed. For example, a noticeable bluing of the star was observed during the deep 1992, 2008, and 2011 minima, while the variations with smaller amplitudes show an increase in B ? V at the photometric minima. The spectral energy distribution for V1027 Cyg from our photometry in the range 0.36 (U)–5.0 (M) μm corresponds to spectral types from G8I to K3I at different phases of the pulsation cycle. Low-resolution spectra of V1027 Cyg in the range λ4400–9200 ?A were taken during 16 nights over the period 1995–2015. At the 1995 and 2011 photometric minima the star’s spectrum exhibited molecular TiO bands whose intensity corresponded to spectral types M0–M1, while the photometric data point to a considerably earlier spectral type. We hypothesize that the TiO bands are formed in the upper layers of the extended stellar atmosphere. We have measured the equivalent widths of the strongest absorption lines, in particular, the infrared Ca II triplet in the spectrum of V1027 Cyg. The calcium triplet (Ca T) with W _λ(Ca T) = 20.3 ± 1.8 ?A as a luminosity indicator for supergiants places V1027 Cyg in the region of the brightest G–K supergiants. V1027 Cyg has been identified with the infrared source IRAS 20004+2955 and is currently believed to be a candidate for post-AGB stars. The evolutionary status of the star and its difference from other post-AGB objects are discussed.     

Photometry of TT Arietis

An analysis of data spanning 24 years shows that a secondary 20^m periodicity is a persistent feature in photometric observations of TT Ari. This period decreases from 27^m in 1961 to 17^m in 1985. The 4^d beat period of 3 _. ^h 2 photometric and 3 _. ^h 3 spectroscopic periods is also apparent in observations of 1966.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.