Photogrammetric Point Determination Using Digital Galileo Ssi Images from Asteroid Ida (original) (raw)

Galileo's Encounter with 243 Ida: An Overview of the Imaging Experiment

Icarus, 1996

in the direction of Ida at the time of observation, suggesting synchronism of its orbital motion and spin. Constraints on We provide an overview of the execution, data, and results Dactyl's orbit yield 4.2 ؎ 0.6 ؋ 10 19 g for Ida's mass and of the solid state imaging (SSI) experiment at the encounter 2.6 ؎ 0.5 g/cm 3 for its bulk density. Unless Ida's bulk porosity of the Galileo spacecraft with the asteroid 243 Ida. Ninety-six is exceptionally high, Ida has moderate to low NiFe content. images of the asteroid, representing 18 time samples during a Subtle color variations across the surface of Ida are associated rotation period (4.633 h), were transmitted to Earth as a result with fresh craters, but, unlike the case for Asteroid 951 Gaspra, of the UT 1993 August 28.70284 encounter. This provided are not correlated with topographic features such as ridges. coverage of ȁ95% of the surface and achieved ground resolu-This difference may be a reflection of a deeper and/or more tions as high as 25 m/pixel. Coverage of most of Ida's surface mobile regolith on Ida. Dactyl's spectral reflectance is similar is available in four colors, with limited regions in five colors, to, but quantitatively distinct from the surface of Ida itself. at resolutions up to 105 m/pixel. A natural satellite of Ida, This difference may reflect compositional differences between called Dactyl, was discovered in a prograde (with respect to Dactyl and Ida, which in turn may have originated in an only Ida's spin), near-equatorial, orbit moving slowly (ȁ 6 m/sec) partially differentiated Koronis parent body. with a separation of 85 km from Ida.

Difficult cases in photometric studies of asteroids

2016

1. Astronomical Observatory Institute, Faculty of Physics, A. Mickiewicz University, S loneczna 36, 60-286 Poznań, Poland 2. 4438 Organ Mesa Loop, Las Cruces, New Mexico 88011 USA 3. Bisei Spaceguard Center, Japan Spaceguard Association, 1716-3, Okura, Bisei, Ibara, Okayama 714-1411, Japan 4. Mt. Suhora Observatory, Pedagogical University, Podchor ↪ ażych 2, 30-084, Cracow, Poland 5. Observatóıre du Bois de Bardon, 16110 Taponnat, France 6. Association T60, 14 avenue Edouard Belin, 31400 Toulouse, France 7. Astrophysics Division, Institute of Physics, Jan Kochanowski University, Świ ↪ etokrzyska 15, 25-406 Kielce, Poland 8. Uzhhorod National University, Uzhgorod, Ukraine 9. Kepler Institute of Astronomy, University of Zielona Góra, Lubuska 2, 65-265 Zielona Góra, Poland

Multiple asteroid systems from the UkrVO digitized photographic plates

Communications of the Byurakan Astrophysical Observatory, 2020

Several catalogs of various celestial objects were compiled based on the processing of Ukrainian VO archives and observatories in Kitab (Uzbekistan) and Baldone (Latvia). We analyzed the catalogs of asteroid positions and B-magnitudes obtained from the processing of digitized photographic plates and selected from them asteroids, which are known as multiple. Positional observations cover the period 1973-1993 and may be useful for a more detailed study of the dynamics of these systems. The obtained photometric characteristics of asteroids will be useful for studying changes in brightness.

Photometric Observations and Modeling of Asteroid 1620 Geographos

Icarus, 1996

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.

The representation of asteroid shapes: A test for the inversion of Gaia photometry

Planetary and Space Science, 2012

ABSTRACT It is common practice nowadays to derive spins and 3D shapes of asteroids from the inversion of photometric light curves. However, this method requires, in general, a good number of photometric points and dedicated observing sessions. On the other hand, the photometric observations carried out by the Gaia mission will be sparse and their number relatively small.For this reason, a multi-parametric shape described by a large number of elementary facets cannot probably be derived from Gaia data alone. Therefore, the Data Processing and Analysis Consortium (DPAC), implemented a simpler solution as an unattended data reduction pipeline, which relies on three axial ellipsoids for the shape representation.However, overall accuracy of such triaxial shape solutions has to be assessed. How adequate is an ellipsoidal approximation to represent the overall properties of an irregular body? Which error is made on the volume in comparison to a more accurate model with irregular shape?To answer these questions, we have implemented numerical procedures for comparing ellipsoids to more complex and irregular shapes, and we performed a full simulation of the photometric signal from these objects, using both shape representations. Implementing the same software algorithm that will be used for the analysis of Gaia asteroid photometry, rotation period, spin axis orientation and ellipsoidal shape were derived from simulated observations of selected Main Belt asteroids assuming a geometric scattering model (work is in progress for more complex scattering models).Finally, these simulated Gaia results were compared to check the relevance of the ellipsoidal solution in comparison to multi-parametric shapes. We found that the ellipsoids by photometry inversion are closely similar to the best-fitting ellipsoids of the simulated complex shapes and that the error on the asteroid volume (relative to a complex shape) is generally low, usually around 10%.

Shapes and rotational properties of thirty asteroids from photometric data

Icarus, 2003

We have analyzed photometric lightcurves of 30 asteroids, and present here the obtained shapes, rotational periods and pole directions. We also present new photometric observations of five asteroids. The shape models indicate the existence of many features of varying degrees of irregularity. Even large main-belt asteroids display such features, so the resulting poles and periods are more consistent than those obtained by simple ellipsoid-like models. In some cases the new rotational parameters are rather different from those obtained previously, and in a few cases there were no proper previous estimates at all. and 694 Ekard. New observations of 21 Lutetia, 37 Fides, 85 Io, 129 Antigone, and 135 Hertha are presented in Section 4. In Section 5 we sum up the paper and discuss some future prospects of the analysis of photometric and complementary data.

Dactyl: Galileo Observations of Ida's Satellite

Icarus, 1996

m across. The image includes an intriguing crater chain, but no grooves, ridges, or sharp edges are evident. In terms of limb Galileo's flyby of 243 Ida in August 1993 led to the discovery roughness, Dactyl is much smoother than Ida, but comparable of a small satellite, Dactyl, some 85 km from the asteroid's to the two satellites of Mars, Phobos and Deimos. center. From Earth at mean opposition, the satellite is a V ‫؍‬ While the satellite's origin is uncertain, a likely scenario ؉20.3 mag object (some 6.7 magnitudes fainter than Ida).

Photometry and models of eight near-Earth asteroids

Icarus, 2004

We present new observations and models of the shapes and rotational states of the eight near-Earth Asteroids (1580) Betulia, (1627) Ivar, (1980) Tezcatlipoca, (2100) Ra-Shalom, (3199) Nefertiti, (3908) Nyx, (4957) Brucemurray, and (5587) 1990 SB. We also outline some of their solar phase curves, corrected to common reference geometry with the models. Some of the targets may feature sizable global nonconvexities, but the observable solar phase angles were not sufficiently high for confirming these. None is likely to have a very densely cratered surface. We discuss the role of the intermediate topographic scale range in photometry, and surmise that this scale range is less important than large or small scale lengths.