258 research outputs found
Objectives and Management of the Gaia-FUN-SSO Network
4 p.International audienceGround-based observations in addition to observations by space missions can be a very efficient way to get complementary data, to go beyond the primitive objectives of this mission and actually to increase the scientific return of the mission. This strategy is used in the frame of several missions, for example when a ground-based network is required to get a large coverage of observation, for a fast verification of an event or its follow-up with instruments unavailable on board. For example, the Corot space observatory for asterosismology and detection and study of exoplanets, or the future Swom space mission for the detection and study of Gamma Ray Bursts, apply this strategy. The space-ground synergy is also an efficient strategy for the Gaia mission and in particular for the Solar System Object science (Thuillot et al., 2010). Several ground-based activities are being organized in the frame of the Gaia mission: the GBOT (Ground based Optical Tracking of Gaia, see Altmann et al. ibid) is a specific observing program of the probe itself; observing sites are also foreseen in a Science Alert Network for various science alerts mainly dedicated to astrophysical objects, photometry and spectroscopy; the Gaia-FUN-SSO program, presented here, is focused on an astrometric follow-up of specific Solar System objects
Near-Earth Asteroids Astrometry with Gaia and Beyond
4 p.International audienceGaia is an astrometric mission that will be launched in 2012 and will observe a large number of Solar System Objects down to magnitude 20. The Solar System Science goal is to map thousand of Main Belt Asteroids (MBAs), Near Earth Objects (NEOs) (including comets) and also planetary satellites with the principal purpose of orbital determination (better than 5 mas astrometric precision), determination of asteroid mass, spin properties and taxonomy. Besides, Gaia will be able to discover a few objects, in particular NEOs in the region down the solar elongation (45°) which are harder to detect with current ground-based surveys
Astrometric observations of Phobos and Deimos during the 1971 opposition of Mars
Accurate positional measurements of planets and satellites are used to
improve our knowledge of their dynamics and to infer the accuracy of planet and
satellite ephemerides. In the framework of the FP7 ESPaCE project, we provide
the positions of Mars, Phobos, and Deimos taken with the U.S. Naval Observatory
26-inch refractor during the 1971 opposition of the planet. These plates were
measured with the digitizer of the Royal Observatory of Belgium and reduced
through an optimal process that includes image, instrumental, and spherical
corrections to provide the most accurate data. We compared the observed
positions of the planet Mars and its satellites with the theoretical positions
from INPOP10 and DE430 planetary ephemerides, and from NOE and MAR097 satellite
ephemerides. The rms residuals in RA and Dec. of one position is less than 60
mas, or about 20 km at Mars. This accuracy is comparable to the most recent CCD
observations. Moreover, it shows that astrometric data derived from
photographic plates can compete with those of old spacecraft (Mariner 9, Viking
1 and 2).Comment: 5 pages, 3 figure
Australian participation in the Gaia follow-up network for solar system objects
The Gaia satellite, planned for launch by the European Space Agency (ESA) in 2013, is the next-generation astrometry mission following Hipparcos. Gaiaâs primary science goal is to determine the kinematics, chemical structure, and evolution of the Milky Way Galaxy. In addition to this core science goal, the Gaia space mission is expected to discover thousands of Solar System objects. Because of orbital constraints, Gaia will only have a limited opportunity for astrometric follow-up of these discoveries. In 2010, the Gaia Data Processing and Analysis Consortium (DPAC) initiated a program to identify ground-based optical telescopes for a Gaia follow-up network for Solar System Objects to perform the following critical tasks: confirmation of discovery, identification of body, object tracking to constrain orbits. To date, this network comprises 37 observing sites (representing 53 instruments). The Zadko Telescope, located in Western Australia, was highlighted as an important network node because of its southern location, longitude, and automated scheduling system. We describe the first follow-up tests using the fast moving Potentially Hazardous Asteroid 2005 YU55 as the target
Cassini ISS mutual event astrometry of the mid-sized Saturnian satellites 2005-2012
Reproduced with permission from Astronomy & Astrophysics, © ES
Enabling discovery of solar system objects in large alert data streams
With the advent of large-scale astronomical surveys such as the Zwicky
Transient Facility (ZTF), the number of alerts generated by transient, variable
and moving astronomical objects is growing rapidly, reaching millions per
night. Concerning solar system minor planets, their identification requires
linking the alerts of many observations over a potentially large time, leading
to a very large combinatorial number. This work aims to identify new candidates
for solar system objects from massive alert data streams produced by
large-scale surveys, such as the ZTF and the Vera C. Rubin Observatory's Legacy
Survey of Space and Time. Our analysis used the Fink alert broker capabilities
to reduce the 111,275,131 processed alerts from ZTF between November 2019 and
December 2022 to only 389,530 new solar system alert candidates over the same
period. We then implemented a linking algorithm, Fink-FAT, to create real-time
trajectory candidates from alert data and extract orbital parameters. The
analysis was validated on ZTF alert packets linked to confirmed solar system
objects from the Minor Planet Center database. Finally, the results were
confronted against follow-up observations. Between November 2019 and December
2022, Fink-FAT extracted 327 new orbits from solar system object candidates at
the time of the observations, over which 65 were still unreported in the MPC
database as of March 2023. After two late follow-up observation campaigns of
six orbit candidates, four were associated with known solar system minor
planets, and two remain unknown. Fink-FAT is deployed in the Fink broker and
successfully analyzes in real time the alert data from the ZTF survey by
regularly extracting new candidates for solar system objects. Our scalability
tests also show that Fink-FAT can handle the even larger volume of alert data
that the Rubin Observatory will send.Comment: submitted to A&
The Caviar software package for the astrometric reduction of Cassini ISS images: description and examples
N.J.C. is grateful to the Paris Observatory for funding as an
invited researcher at the IMCCE. We thank the FP7-ESPaCE European program
for funding under the agreement No. 263466. N.J.C. and C.D.M. thank the Science
and Technology Facilities Council (Grant No. ST/P000622/1) for financial
support. This work was also supported by the International Space Science Institute
(ISSI)
Astrometric positions for 18 irregular satellites of giant planets from 23 years of observations
The irregular satellites of the giant planets are believed to have been
captured during the evolution of the solar system. Knowing their physical
parameters, such as size, density, and albedo is important for constraining
where they came from and how they were captured. The best way to obtain these
parameters are observations in situ by spacecrafts or from stellar occultations
by the objects. Both techniques demand that the orbits are well known. We aimed
to obtain good astrometric positions of irregular satellites to improve their
orbits and ephemeris. We identified and reduced observations of several
irregular satellites from three databases containing more than 8000 images
obtained between 1992 and 2014 at three sites (Observat\'orio do Pico dos Dias,
Observatoire de Haute-Provence, and European Southern Observatory - La Silla).
We used the software PRAIA (Platform for Reduction of Astronomical Images
Automatically) to make the astrometric reduction of the CCD frames. The UCAC4
catalog represented the International Celestial Reference System in the
reductions. Identification of the satellites in the frames was done through
their ephemerides as determined from the SPICE/NAIF kernels. Some procedures
were followed to overcome missing or incomplete information (coordinates,
date), mostly for the older images. We managed to obtain more than 6000
positions for 18 irregular satellites: 12 of Jupiter, 4 of Saturn, 1 of Uranus
(Sycorax), and 1 of Neptune (Nereid). For some satellites the number of
obtained positions is more than 50\% of what was used in earlier orbital
numerical integrations. Comparison of our positions with recent JPL ephemeris
suggests there are systematic errors in the orbits for some of the irregular
satellites. The most evident case was an error in the inclination of Carme.Comment: 9 pages, with 3 being online materia
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