Estimate of the optimum measuring time in the synchronous photometry of optical sources

The note shows how to estimate accurately the optimum measuring time in the measurement of a periodical optical source by means of a synchronous photometer affected by phase-tracking error. The procedure used can be easily generalized to sources or signal patterns not considered here. The optimum number of scans to be averaged results to be typicallyN _opt≈0.5r/ɛ for an optical source of Lorentzian signal pattern, wherer is the duty cycle of the pulsed component and ɛ the relative truncation error of the local sync to the source period. Work supported by Consiglio Nazionale delle Ricerche, Gruppo Nazionale di Astronomia, Settore Tecnologie Astronomiche. Trieste Observatory — Instruments and Data Processing Group (4/76).     

PAOLO: A Polarimeter Add‐On for the LRS Optics at a Nasmyth focus of the TNG

We describe a new polarimetric facility available at the Istituto Nazionale di AstroFisica / Telescopio Nazionale Galileo at La Palma, Canary islands. This facility, PAOLO (Polarimetric Add‐On for the LRS Optics), is located at a Nasmyth focus of an alt‐az telescope and requires a specific modeling in order to remove the time‐ and pointing position‐dependent instrumental polarization. We also describe the opto‐mechanical structure of the instrument and its calibration and present early examples of applications. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A real-time spectrum analyser with on-line definition of the confidence levels

This paper describes a real-time spectrum analyser with on-line definition of the confidence levels built at Trieste Observatory for a research program on periodical components of unknown period in optical sources. The system is realized by a photon counting photometer on-line to a computer that elaborates in real-time the data from the photometer and displays the spectrum of the source measured. The spectrum is normalized to unity mean value and the display is calibrated by the confidence levels relative to the distribution of the spectrum displayed. Some experimental data show the performance of the machine that operates in real-time at full efficiency up to 160 Hz. Work supported by Consiglio Nazionale delle Ricerche, Gruppo Nazionale di Astronomia, Settore Tecnologie Astronomiche. Trieste Observatory — Instruments and Data Processing Group (1/76).     

The multifunction photoelectric photometer of Torino Observatory

The paper describes the design and the realization of a multiple-function photoelectric photometer made by Trieste Observatory for Torino Observatory. The system design shows a two-beam, sequential multiband photon counting and analog photoelectric photometer configuration based on a PDP8/E computer for the control and data acquisition and elaboration. The actual realization of the system and the use of it in the one-beam configuration operating now at torino Observatory shows the advantages of such a solution and the easiness in modifying and determining the system functions by software programs rather than by hardware specials. Work supported by Consiglio Nazionale delle Ricerche, Gruppo Nazionale di Astronomia, Settore Tecnologie Astronomiche. The realization of the machine was fully supported by Torino Observatory. Trieste Observatory-Instruments and Data Processing Group (5/76).     

Note on tidal evolution of the Earth-Moon system

The need is pointed out of a re-discussion of the past tidal evolution of the Earth-Moon system as a boundary-value problem on the time-scale indicated by radiometric dating of lunar soils returned by successive space missions from different localities on the Moon's surface.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

On the apparent secular accelerations of the Moon and the Sun

The discussion of tidal friction in the Earth-Moon system given in successive editions ofThe Earth by Jeffreys is shown to contain a serious dynamical error. When the treatment is corrected, it shows that the moment of inertia of the Earth must be changing. The apparent secular accelerations of the Moon and Sun require a diminishing moment of inertia, and the rate is in agreement with the phase-change hypothesis for the nature of the core.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

The stability and evolution of the solar system

The known history of the solar system is discussed, also the types of dynamical problems exhibited by members of the solar system and the solutions suggested for a number of such problems. The recent work of Walker, Emslie and Roy, on Empirical Stability Criteria in Many Body Problems is also mentioned.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

Time evolution of grains in the protosolar nebula

The problem of the motion of grains in the protosolar nebula is discussed. Time scales of the vertical and radial displacement are computed. The structure of the dust disk that can be formed is discussed in the framework of different protosolar nebula models.The results obtained under the hypothesis of quiescience of the gas component are compared with those in presence of a fully developed turbulence.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

Contribution to the structural interpretation of the Valles Marineris-Noctis Labyrinthus-Claritas Fossae regions of Mars

An inventory of tectonic trends observed in the MC 17 (Phoenicis Lacus) and MC 18 (Coprates) Mars quadrangles, has been constructed on the basis of Mariner 9 and Viking Orbiter images, with regard to their structural significance within the martian history. A scenario for the principal periods and their mechanisms, is proposed with regard to the uplift of the Tharsis Montes-Syria Planum dome.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

A Monte Carlo estimate of the fraction of comets developing into sizeable asteroidal bodies

We present results of Monte Carlo simulations of orbital evolution showing that assuming a steady state there are roughly 50 extinct comets per active one in the Mars-crossing Jupiter family. The large number of extinct comets thus expected compared with the absence of observed apollo or Amor asteroids with aphelion distances greater than 4.2 AU indicates that less than five percent of the extinct comets survive as sizeable asteroidal bodies.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

Mineralogical characterization of some basaltic asteroids in the neighborhood of (4) Vesta: first results

We present reflectance spectra of 19 V-type asteroids obtained at the 3.6 m Telescopio Nazionale Galileo covering 0.8 to 2.5 μm. For 8 of these asteroids we obtained also visible spectra in the same observational run. The range from 0.8 to 2.5 μm, encompassing the 1 and 2 μm pyroxene features, allows a precise mineralogical characterization of these asteroids. The obtained data suggests the possible coexistence of distinct mineralogical groups among the V-type asteroids, either probing different layers of (4) Vesta or coming from different bodies. No clear correlation was found between mineralogies and the objects being, or not, member of the Vesta dynamical family.     

Surface studies of asteroids with the Faint Object Camera of the Space Telescope

Minor planets have been observed in the last few years for physical properties using photometry, polarimetry and IR-radiometry. Using the Faint Object Camera (FOC) of the Space Telescope (ST) it will be possible for the first time to observe a large number of asteroids with direct imaging systems.We propose to use the FOC with high resolution mode to examine minor planets with respect to (a) diameters and shapes, (b) surface and detail studies, (c) densities and (d) possible binary nature of selected asteroids.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

The Data Flow, from Observations to the Archive: Simulating the Case of TNG

The telescopes of the new generation allow an archive to be built as a section of data management; nevertheless, careful planning is needed and data handling needs to be designed together with the control system of the telescope itself, both for space-borne and for ground-based facilities. Simulations are essential to understand how observations will be archived, and to build and test an archiving system capable of dealing efficiently with the expected data flow.The TNG (Telescopio Nazionale Galileo) will be one of the first ground-based observing facilities where archiving of both technical and scientific data will be made directly at the telescope as a natural extension of the data handling chain. The results obtained testing the prototype implementation of the archive system at the TNG with a simulated data flow will be shown.     

Effects of a close encounter with Jupiter on different populations of planet-crossing objects

The evolutions of different planet-crossing populations due to a close encounter with Jupiter are examined and the implications on materials displacement throughout the solar system are discussed. The effects of the encounter are shown to be very important for those planet-crossers that could be responsible of planets surface cratering.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

The Kepler problem: A unifying view

This paper is an attempt to bring unity in the study of the classical Kepler problem by combining, through simple vectorial and quaternionic techniques, its two peculiar aspects: the determination of the constants of the motion and the regularization at the origin.Research supported by the Consiglio Nazionale delle Ricerche of Italy (C.N.R.-G.N.F.M.).     

Origin of the Olympus Mons aureole and perimeter scarp

The aureole materials that form an annulus of corrugated terrain surrounding Olympus Mons are considered to be the product of mass movement. The scarp at the mountain's foot formed as a result of this massive removal of material from the volcano's outer flanks. This interpretation is supported by a comparison of the amount of material originally available before scarp formation, and the present volume of aureole materials. On the basis of distribution, surface textures and theoretical considerations it is considered that the aureole was produced by a series of megaslides, rather than by a flow mechanism. Production of the megaslides may have been assisted by a period of widespread melting of permafrost.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

The spectrum of ɛ Aurigae outside eclipse

The identification, the equivalent widths, the profiles and the radial velocities as deduced from 18 spectra of Aurigae are presented and discussed.The observations have been made at the Astronomical Observatory of Haute Provence (CNRS). This work has been partially supported by a contract of Consiglio Nazionale delle Ricerche (CNR).     

Formation of the sodium clouds and the regolith on Io by micrometeoroid impacts

The effects of the amount of sodium ions, their solar angles correlation, temperature and velocities, have been explained as consequences of the almost full penetration of the second mode of micrometeorite fluxes (M>10^–8 g) across the Io atmosphere to its surface, whereas volcanism may satisfy only the amount of sodium.Conclusions about the formation of fine grains on the Io surface, unflooded by lava, are presented. Due to its large specific surface (m² g^–1) the interaction of this topsoil and the Io atmosphere is no less important than the lava-atmosphere interaction.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.From September 1979.     

Variation of the profiles of medium-strong photospheric lines with heliographic latitude

The asymmetric profiles of 11 metallic lines are studied, at = 0.3, as functions of . Their variations cannot be interpreted as due to temperature effects, but might imply a dependence on of the photospheric velocity field.This work has been supported by the CNR through the Gruppo Nazionale di Astronomia.     

Planetary close encounters: Importance of nearly tangent orbits

It is shown that close encounters between Jupiter and minor bodies are generally more efficient if the initial orbit of the small body is nearly tangent to that of the planet. Starting from the analysis of the results of previous numerical simulations, some indications on the mobility of the small bodies in the semiaxis-eccentricity diagram are given.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratory di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.