Optical Spectroscopy of Comet C/2000 WM1 (LINEAR) at the Guillermo Harro Astrophysical Observatory in Mexico

We present a preliminary analysis of medium resolution optical spectra of comet C/2000 WM1 (LINEAR) obtained on 22 November 2001. Theemission lines of the molecules C₂, C₃, CN, NH₂,H₂O⁺ and presumably CO (Asundi and triplet bands) and C₂ ^-were identified in these spectra. By analysing the brightnessdistributions of the C₂, C₃, CN emission lines along theslit of the spectrograph we determined some physical parameters of theseneutrals, such as their lifetimes and expansion velocities inthe coma. The Franck–Condon factors for the CO Asundi bands and C₂ ^- bands were calculated using a Morse potential model.     

Observations of OH maser lines at an 18-cm wavelength in 9P/Temper1 and Lulin C/2007 N3 comets with RT-22 at the Crimean Astrophysical Observatory

Investigations on OH maser lines in comets have been performed with the RT-22 at CrAO. The results of observations of 9P/Temper1 and Lulin C/2007 N3 comets in the OH molecule line at a wavelength of 18 cm are presented. An original technique for observation data analysis has been developed. The gas production rate of OH molecules in these comets is estimated.     

Observation of comets C/2009 R1 (McNaught) and 17P/holmes in the OH line at a wavelength of 18 cm

The observation results for comets C/2009 R1 (McNaught) (June 14–28, 2010) and 17P/Holmes (November 25–December 3, 2007) performed in the line of the OH molecule and at a wavelength of 18 cm are presented. The gas productivity of the OH molecule for comet C/2009 R1 (McNaught) (June 14–28, 2010) as a function of the heliocentric distance (0.42–0.62 au) is determined.     

Astrometric results of observations at Russian observatories of mutual occultations and eclipses of Jupiter’s Galilean satellites in 2009

In 2009, in five Russian observatories photometric observations of Jupiter’s Galilean satellites during their mutual occultations and eclipses were carried out. Based on these observations, an original method was used to ascertain astrometric results such as the difference between the coordinates of pairs of satellites. Fifty-three phenomena were successfully observed. A total of 94 light curves of satellites were measured. The error in the coordinates of satellites due to random errors in photometry, calculated on all data obtained, was 0.041″ in right ascension and 0.046″ in declination. The discrepancies between the theory and observations in these coordinates was found to be 0.060″ and 0.057″, respectively. The results were uploaded to the common database for all observations of natural satellites of planets at the Natural Satellites Data Center (NSDC), which is available online at http://www.sai.msu.ru/neb/nss/index.htm. For the first time in the practice of photometric observations of satellites in epochs of mutual occultations and eclipses a new method of observation was tested, which eliminates from astrometric results the major systematic errors caused by an inaccurate account of the background level. The tests were conducted in the Terskol Observatory and the observatory of the Crimean laboratory of the Sternberg State Astronomical Institute of the Moscow State University. The application of the new method showed that the elimination of the background level at these observatories was carried out correctly.     

Investigation of the motions of fast stars based on observations with the Pulkovo normal astrograph

Astrometric CCD observations of 1123 stars with large proper motions (μ > 300 mas yr⁻¹) from the LSPM (I/298) catalog in the declination zone +30°–+70° have been carried out with the Pulkovo normal astrograph since 2006. The observational program includes mostly stars that previously have not entered into high-accuracy projects to determine the proper motions. Our studies are aimed at determining new proper motions of fast stars in the HCRF/UCAC3 system and searching for stars with invisible companions in the immediate Galactic neighborhoods of the Sun. Having analyzed about 10 000 CCD frames, we have obtained the equatorial coordinates of 414 program stars in the HCRF/UCAC3 system at an accuracy level of 10–50 mas and determined their new proper motions. To derive the proper motions, we have used the data from several star catalogs and surveys (M2000, CMC14, 2MASS, SDSS) as early epochs. The epoch differences range from 5 to 13 years (on average, about 10 years); the mean accuracy of the derived proper motions is 4–5 mas yr⁻¹. For 70 stars, we have revealed significant differences between the derived proper motions and those from the LSPM and I/306A catalogs (these proper motions characterize the mean motion of the photocenter in 50 years or more). Apart from systematic errors, these differences can result from the existence of invisible components of the program stars.     

Seismoacoustic lunar fields and lunar electromagnetic (nonthermal) emission

For better insight into lunar radio emissions, observations of the Moon were made during the maximal Geminids meteor shower and during the lunar eclipse without external effects. Statistical processing of the obtained data was carried out. It was found that the lunar endogenous and exogenous processes are displayed in both the seismic-emission fields and lunar nonthermal electromagnetic emissions. Both types of signals demonstrate good correlation. The seismic and electromagnetic emission processes have common periodicities, some of which determine the internal structure of the Moon. Similar regularities are expected for other bodies of the Solar System.     

A new reduction of digitized photographic plates with selected asteroids obtained with the normal astrograph of the Pulkovo Observatory from 1948 to 1990

The results of a new reduction of 1545 photographic observations of 14 selected asteroids obtained with the Normal Astrograph of the Pulkovo Observatory from 1948 to 1990 are presented. Photographic plates stored in the archive of the observatory were digitized with a general purpose flatbed scanner using a specially developed technique. The accuracy of the reduction of photographic plates is measured. The UCAC3 catalogue has been used as a reference. Residual differences between coordinates of stars in the reference catalogue are used to analyze and tacking into account obtained instrumental systematic errors. Equatorial coordinates of 1378 individual observations of target asteroids are obtained. They are compared with the results of the reduction of the material made earlier. Among the objects of the background, positions of 1475 stars with large proper motions from the LSPM catalogue are measured.     

The role of photochemical processes in evolution of the isotopic composition of the atmosphere of Titan

Molecular nitrogen, the main component of the modern atmosphere of Titan, may have formed without significant changes in the nitrogen and hydrogen isotopic composition from the clathrate hydrate of ammonia NH₃ · H₂O_SLD, which is the main accreted form of nitrogen. The most preferable transformation mechanism of NH₃ · H₂O_SLD into atmospheric N₂ is its thermal decomposition in the interior of Titan rather than the photochemical decomposition of ammonia in the upper atmosphere of early Titan. The photolysis of ammonia does not lead to a change in the isotopic composition of nitrogen, as all the nitrogen remains in Titan’s atmosphere. The photolysis of NH does not lead to a change in the isotopic composition of nitrogen in Titan’s atmosphere. Fractionation of hydrogen and nitrogen isotopes during the impacts of comets with Titan does not seem to be significant either. It will be possible to determine the dissociative fractionation factor, the original ratio ¹⁴N/¹⁵N, and the mass of Titan’s original atmosphere when fractionation of nitrogen isotopes in Titan’s atmosphere is examined in additional theoretical and experimental studies that take into account processes occurring during the formation of a system of Saturn’s satellites.