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We investigate surface changes near two lunar craters formed on March 17 and September 11, 2003, using high-resolution imagery data (0.5 m/pixel) of the LRO narrow angle camera. The phase- and temporal ratio techniques are applied. Using these techniques reveals a slight “butterfly-wings” pattern around the March 17 crater. This pattern is not seen on usual brightness images. The observed dark halos around the craters may be formed by thin deposits of vapor products at the impacts. Rough estimates show that only 100 g of the nano-phase iron (npFe0) is needed to generate the darkening effect, if the iron is spread in a layer of 10 nm thickness on an area with a radius of 70 m. A portion of the ejected materials is seen around the craters as dark and bright splotches. The dark splotches could be produced when excavated material interacts with the cloud of evaporated substance and then falls down to the surface.

We investigate a southern portion of Mare Vaporum using Chandrayaan-1 M3 images for which we suppress striped noise. Additional data processing allows us to analyze such spectral parameters as the depths and positions of the absorption bands near 1 and 2 μm. Mineral types were mapped using the cluster analysis of Adams diagram for pyroxenes. We inspected, in particular, the areas of pyroclastic deposits around the crater Hyginus and small areas in the crater which have the 2 μm band shifted to longer wavelengths. We examined the areas with phase-ratio analysis of LROC NAC images: the areas associated with clinopyroxenes are distinguished both in albedo and phase-ratio (56°/23°) images, perhaps, having higher roughness than surrounding surface; Whereas the areas associated with pyroclastic glasses does not seen neither in albedo nor phase-ratio images.

The results of photometric observations of eight main-belt asteroids with low surface albedo are presented. The magnitude–phase dependences including low phase angles ( 12.497 ± 0.001 h ), 309 Fraternitas ( 11.205 ± 0.005 h ), 615 Roswitha ( 4.422 ± 0.001 h ) and 954 Li ( 7.207 ± 0.002 h ). The color indexes B–V, V–R and R–I have been determined for some asteroids.

Photometric data on 17 binary near-Earth asteroids (15 of them are certain detections, two are probables) were analysed and characteristic properties of the near-Earth asteroid (NEA) binary population were inferred. We have found that binary systems with a secondary-to-primary mean diameter ratio D s / D p ⩾ 0.18 concentrate among NEAs smaller than 2 km in diameter; the abundance of such binaries decreases significantly among larger NEAs. Secondaries show an upper size limit of D s = 0.5 – 1 km . Systems with D s / D p ⩽ 0.5 are abundant but larger satellites are significantly less common. Primaries have spheroidal shapes and they rotate rapidly, with periods concentrating between 2.2 to 2.8 h and with a tail of the distribution up to ∼4 h. The fast rotators are close to the critical spin for rubble piles with bulk densities about 2 g/cm3. Orbital periods show an apparent cut-off at P orb ∼ 11 h ; closer systems with shorter orbital periods have not been discovered, which is consistent with the Roche limit for strengthless bodies. Secondaries are more elongated on average than primaries. Most, but not all, of their rotations appear to be synchronized with the orbital motion; nonsynchronous secondary rotations may occur especially among wider systems with P orb > 20 h. The specific total angular momentum of most of the binary systems is similar to within ±20% and close to the angular momentum of a sphere with the same total mass and density, rotating at the disruption limit; this suggests that the binaries were created by mechanism(s) related to rotation near the critical limit and that they neither gained nor lost significant amounts of angular momentum during or since formation. A comparison with six small asynchronous binaries detected in the main belt of asteroids suggests that the population extends beyond the region of terrestrial planets, but with characteristics shifted to larger sizes and longer periods. The estimated mean proportion of binaries with D s / D p ⩾ 0.18 among NEAs larger than 0.3 km is 15 ± 4 % . Among fastest rotating NEAs larger than 0.3 km with periods between 2.2 and 2.8 h, the mean proportion of such binaries is (66+10−12)%.

Lightcurve observations of 16 near-Earth objects (NEOs) and 2 Mars-crossers in 1996–1999 from three observational sites are presented. Eight objects were observed shortly after their discovery within the follow-up program of NEO observations. We were able to determine rotation periods for 14 asteroids. For 8 objects (5626, 5732, 1998 FM5, 1998 FX2, 1998 UT18, 1998 VO33, 1999 RQ36, 1999 US3) our determinations constitute new results while in the remaining 6 cases (3200, 4341, 7025, 7822, 11066, 1992 QN) we could improve or confirm previously published periods. We also put constraints on the spin vector of 3200 Phaethon.

We present the results of photometric observations of 1996 FG3, 1998 PG, and (5407) 1992 AX. Each asteroid has a complex lightcurve that can be described as the coaddition of two independent components, one with a short synodic period P1 of several hours, and another with a longer synodic period P2. For 1996 FG3, the shape of the long-period component strongly suggests a system of two bodies in bound orbits about their common center of mass, displaying both mutual eclipses and mutual occultations. We estimate the following parameters of the binary system: the primary's rotation period is P1=(3.5942±0.0002) h, the system's orbital period is P2=(16.135±0.005) h, the system's semimajor axis a=(1.7±0.3) dp, the eccentricity is 0.05±0.05, and the secondary-to-primary diameter ratio ds/dp=0.31±0.02. The measured color indices suggest that 1996 FG3 belongs to the C taxonomic class; assuming the geometric albedo p=0.06 typical for the class, we estimate the diameter of the primary dp=1.4 km. For 1998 PG and (5407), the evidence for binary systems is less conclusive. However, assuming a binary model, we estimate that both systems have a secondary-to-primary diameter ratio ds/dp≥0.3. For 1998 PG, the primary and secondary rotation periods are P1=(2.51620± 0.00003) h and 2P2=(14.007±0.0014) h, respectively. (If the secondary's rotation is tidally coupled to the orbital motion, the latter is also the system's orbital period.) For (5407), the primary's rotation period is P1=(2.54878±0.00007) h, and the orbital period is 2P2=(13.5196±0.0016) h. The color indices of 1998 PG are consistent with an S classification. Assuming p=0.16, the primary's diameters are dp=0.9 and 4.0 km for 1998 PG and (5407), respectively. The finding of the three objects doubles the known sample of probable/possible binary asteroids. The six known objects are so similar in some of their characteristics that we expect that most or all of them have been formed by the same mechanism, such as the tidal disruptions during close encounters with Earth proposed by Bottke and Melosh (Nature281, 51, 1996). The population of binary asteroids among small, especially near-Earth, asteroids seems to be significant. Our new observations support an earlier estimate that 17% of NEAs are binary (uncertainty factor of 2).

Polarimetric and photometric observations of Comet C/1996 B2 Hyakutake were carried out at the 70-cm telescope of Kharkov State University Observatory from March 25 to April 7, 1996. The goal of the observations was to determine the polarization maximum of the cometary continuum. We have found that the maximal degrees of polarization in the blue (4845 A) and red (6840 A) continuum domains are 24.0% and 26.1%, respectively, and lie at a phase angle close to 94°, slightly dependent on wavelength. According to the gas-to-dust ratio and color, Comet Hyakutake belongs to the group of dusty comets such as West 1976 VI, P/Churyumov–Gerasimenko 1982 VIII, P/Kopff 1983 XIII, P/Hartley–IRAS 1984 III, P/Giacombini–Zinner 1985 XIII, P/Halley 1986 III, Bradfield 1987 XXIX, Liller 1988 V, Levy 1990 XX, and P/Faye 1991 XXI. The polarization data for comet Hyakutake are in good agreement with the data for these comets in the 37°–73° overlap region of phase angles. Consequently, the maximum of Hyakutake's polarization may be taken as the maximum of polarization at least of this group of dusty comets. The fluxes for the C 2 and C 3 emission bands and dust continuum and the corresponding production rates for Comet Hyakutake are given.

Photometric observations of 1620 Geographos in 1993 and 1994 are presented and, in combination with previously published data, are used to derive models of Geographos. We estimate that the sidereal period of rotation is 0.21763860 ± 0.00000003 days (5h13m23.975s± 0.003s). The sense of rotation is retrograde. The ecliptic coordinates of the spin angular velocity vector are estimated to λp= 56° ± 6° and βp= −47° ± 4° (equinox J2000.0). The lightcurve amplitudes are well-explained by an ellipsoidal model with axis ratiosa/b= 2.58 ± 0.16 andb/c= 1.00 ± 0.15. Models that have one or both ends more sharply pointed than the ellipsoid improve the fit to the observations. There are no significant indications of albedo variegation, but non-geometric scattering effects are tentatively suggested based on significant rotational color variation.

New photoelectric observations for 17 Thetis (1985, 1993, 1994-95), 52 Europa (1992, 1994), 532 Herculina (1982, 1988, 1992), and 704 Interamnia (1993) carried out at seven observatories, are presented. Using all available lightcurves, the spin vectors, senses of rotation, and shapes of these asteroids have been determined or refined.

The Apollo asteroid 4179 Toutatis passed within 0.0242 AU of Earth in December 1992, and photometry was obtained by observers from at least 25 sites around the world, at solar phase angles between 121° and 0.2°. The phase curve is well described in the H, G system with a mean H of 15.3 and a slope parameter G of 0.10 ± 0.10. However, the rotational lightcurve is very unusual. The amplitude is large (1.2 magnitudes) and the rotation period is extremely long (several days). Most remarkably, the lightcurve does not appear to be periodic: it is unlikely that a single rotation period can account for the lightcurve even when the rapidly changing viewing and illumination geometry during the close Earth approach is taken into account, though strong lightcurve minima recurred approximately every 7.3 days. The likely explanation is that Toutatis has complex, tumbling, rotation with a characteristic period between 3 and 7 days. As noted by A. W. Harris (1994 Icarus 107, 209-211), the damping time scale from complex to simple rotation for a small, slowly rotating asteroid like Toutatis is so long that complex rotation is expected, but Toutatis is the first asteroid to show such strong observational evidence for complex rotation.

Groundbased photometric observations of asteroid 243 Ida over seven apparitions from 1980 to 1993 allow us to derive a model for its spin vector and shape prior to the August 1993 encounter by the Galileo spacecraft. Two equally likely solutions for the spin vector are at ecliptic coordinates (1950) λp1 = 73, βp1 = -53 or λp2 = 254, βp2 = -55 with an uncertainty of ± 10° in each coordinate. Ida's low orbital inclination restricts the available aspect angles for Earth-based observers so that the spin vector ambiguity cannot be resolved. We offer predictions for the flyby geometry for both solutions, where the Galileo spacecraft images will resolve this ambiguity easily. Ida's rotation is retrograde with a sidereal period of 4.633632 ± 0.000007 hr. Assuming a triaxial ellipsoid model, we estimate axial ratios of a/b = 1.82 ± 0.10 and b/c = 1.15 ± 0.10. The morphology of the observed lightcurves suggest that Ida has a nonuniform albedo distribution, but we cannot completely rule out observational uncertainties or simplifying model assumptions (e.g., convex shape, geometric scattering) as sources for this suggestion. It is not possible to predict uniquely the distribution of any such albedo variegation.

Results of photoelectric observations from Kharkov Astronomical Observatory (Ukraine) are reported. These observations were made between 1985 and 1991. We also include observations of 4 Vesta made in 1981 at Torun Astronomical Observatory (Poland). Most of the lightcurves are in the V band. The first published observations for Asteroids 151, 206, 550, and 705 are reported. We determine or revise synodic periods for four asteroids: 104, 206, 241, and 550. The phase curves are obtained for three asteroids: 44, 104, and 550.

The 1036 Ganymed and 1627 Ivar photoelectric lightcurves presently discussed indicate in the former case a drastic lightcurve shape change, in conjunction with a significant increase of the synodic rotation period; a substantial change in viewing conditions during the apparition, and a complex interaction between these changes and the asteroid's irregular shape, are indicated by the change. In the latter asteroid's case, a prograde rotation rate is apparent in the observed decrease in synodic period. Both asteroids' phase curves exhibit deviations from the H-G magnitude system phase function at large phase angles.