C. Blanco

Lightcurves and phase function of asteroid 44 Nysa during its 1979 apparition

Lightcurves of asteroid 44 Nysa obtained during 20 nights in 1979 as part of a global compaign are presented. The synodic period was 6 hours and 25.3 minutes. The phase coefficient of the primary maximum was 0.026 mag/deg and the absolute V magnitude 7.05. The phase function is linear from 2 to 25 deg, no opposition effect is present.

Digitization and Scientific Exploitation of the Italian and Vatican Astronomical Plate Archives

There is a widespread interest to digitize the precious information contained in the astronomical plate archives, both for the preservation of their content and for its fast distribution to all interested researchers in order to achieve their better scientific exploitation. This paper presents the first results of our large-scale project to digitize the archive of plates of the Italian Astronomical Observatories and of the Specola Vaticana. Similar systems, composed by commercial flat-bed retro-illuminated scanners plus dedicated personal computers and acquisition and analysis software, have been installed in all participating Institutes. Ad-hoc codes have been developed to acquire the data, to test the suitability of the machines to our scientific needs, and to reduce the digital data in order to extract the astrometric, photometric and spectroscopic content. Two more elements complete the overall project: the provision of high quality BVRI CCD sequences in selected fields with the Campo Imperatore telescopes, and the distribution of the digitized information to all interested researchers via the Web. The methods we have derived in the course of this project have been already applied successfully to plates taken by other Observatories, for instance at Byurakan and at Hamburg.

Asteroid 951 Gaspra - Pre-Galileo physical model

Abstract Prior to the October 1991 encounter of 951 Gaspra, asteroids were the only class of Solar System objects not resolved by spacecraft images. Analysis of the data returned by the Galileo spacecraft will apply critical tests to many techniques developed during the past 50 years for deriving physical properties for several hundred asteroids. As a benchmark for comparison, we have applied these techniques to establish in advance our best estimates for Gaspras properties. We estimate it has an elongated shape with a ratio between equatorial axes of about 1.5–1.7. Further, we derive its sidereal rotation period to be 0.2934197 ± 0.0000010 days with its spin vector pointing toward ecliptic coordinates λ 0 = 20° ± 5°, β 0 = +22° ± 5° (or less likely λ 0 = 198° ± 5°, β 0 = +13° ± 5°).

Rotational periods of asteroids II

Abstract In the framework of the photoelectric asteroid observational program undertaken at Catania University to collect lightcurves apt to apply the pole computational methods, the V-band lightcurves and the values of the synodic rotational period and of the average B–V colour index of 5 Astrea, 6 Hebe, 12 Victoria, 13 Egeria, 26 Proserpina, 34 Circe, 63 Ausonia, 66 Maja, 102 Miriam, 140 Siwa, 176 Iduna, 181 Eucaris, 241 Germania, 250 Bettina, 258 Tyche, 313 Chaldea, 335 Roberta, 352 Gisela, 419 Aurelia, 471 Papagena, 537 Pauly, 639 Latona and 984 Gretia are presented.

New rotational periods of 18 asteroids

Abstract The results of photoelectric observations of 18 main-belt asteroids are discussed. The V-band lightcurves, the B–V colors, and the values of the synodic rotational period are presented. There exists no previous determination of the period for 13 of them.

Pole and shape determinaton of asteroids. II

Abstract To update the research work on asteroids to obtain their rotation axis orientation and axes ratios, we went on implementing the collection of lightcurves. By means of new observations carried out and new lightcurves published, we were able to apply the computation methods of the rotation parameters to 18 minor planets. The found values of the pole coordinates and of the axes ratios are reported. For 14 objects, this is the first determination of these elements which are necessary to study the collisional evolution of the asteroids.

Photoelectric and CCD photometry of 951 Gaspra

Abstract The asteroid 951 Gaspra is a fly-by target for the Galileo space mission. This encounter, planned for October 1991, will represent the first possibility to show an asteroid in close-up. In preparation to this close encounter an earth-based international observing campaign started in 1988 /1,2/, with the goal to provide a substantial data base on the photometric and rotational properties of this object. This will allow on one side to support and optimize the planning of the fly-by and, on the other side, to verify the accuracy of current models for the determination of shapes, surface textures, spin axis orientation and composition. In this paper we present the composite lightcurve of 951 Gaspra obtained from photoelectric and CCD observations, carried out during the 1990 apparition at the observatories of Asiago, Catania and Loiano (Italy). We have determined the sidereal rotational period, the prograde sense of rotation, the H and G parameters and the B-V and V-R color indices.

CCD and photon-counting photometric observations of asteroids carried out at Padova and Catania observatories

Abstract We present the results of observational campaigns of asteroids performed at Asiago Station of Padova Astronomical Observatory and at M.G. Fracastoro Station of Catania Astrophysical Observatory, as part of the large research programme on Solar System minor bodies undertaken since 1979 at the Physics and Astronomy Department of Catania University. Photometric observations of six Main-Belt asteroids (27 Euterpe, 173 Ino, 182 Elsa, 539 Pamina, 849 Ara, and 984 Gretia), one Hungaria (1727 Mette), and two Near-Earth Objects (3199 Nefertiti and 2004 UE) are reported. The first determination of the synodic rotational period of 2004 UE was obtained. For 182 Elsa and 1727 Mette the derived synodic period of 80.23 ± 0.08 and 2.981 ± 0.001 h , respectively, represents a significant improvement on the previously published values. For 182 Elsa the first determination of the H – G magnitude relation is also presented.

Physical studies of asteroids XXX: the asteroid 153 Hilda

The asteroid 153 Hilda was studied by photometric, spectroscopic and polarimetric observations during the apparition in 1992. The rotation period was determined to 5.11 hours with a lightcurve amplitude of 0.05 magnitudes. From our spectrum we find 153 Hilda to be of taxonomic type P. The polarization value of -0.23 at a phase angle of 3.2 degrees seems normal for a P-type asteroid. Long term integrations of the orbit shows that it is stable over time intervals of several million years.

Earth-bound observations of asteroid 19 Fortuna as support to HST imaging: lightcurves, pole direction and shape

Abstract To support the 19 Fortuna imaging work performed by the Hubble Space Telescope, this asteroid was photoelectrically observed in September 1993 at Mt. John, Lake Tekapo and Serra la Nave observatories, covering a complete rotational cycle. These observations and the unpublished ones, collected in November 1986 at Torino Observatory, allowed us to compute the value of the synodic rotational period, which results in accordance with that already known. The spin axis direction and the shape of 19 Fortuna were determined by applying the amplitude-magnitude method (Zappala et al. , in Asteroids, Comets, Meteors (edited by C.-I. Lagerkvist and H. Rickman), pp. 73–76. Uppsala Univeritet, Reprocentralen, HSC, Uppsala, 1983) to our data and to those reported in the literature. The values of the pole coordinates are in agreement with the previous determinations, while the ratio between the semi-axes a and b is larger than about 0.1.