W. Thuillot

Astrometry from mutual events of Jovian satellites in 1997

Astrometric results of observations of the mutual events of the Galilean satellites of Jupiter of the PHEMU97 campaign by the Institut de Mecanique Celeste et de Calcul des Ephemerides are presented. These astrometric positions can be directly utilized in the construction of future ephemerides. We attempt here to compare the residuals of the relative astrometric positions of satellites with respect to the E3, G5, E5 and L1 ephemerides. The model to fit the observed light curves includes the intensity variations on the surface of satellites using the mosaics constructed by the teams at the US Geological Survey from Voyager and Galileo imagery.

Saturnian satellite observations made in Brazil during the 1995 opposition with an astrometric analysis

This paper provides an analysis of astrometric measurements of the main Saturnian satellites made thanks to CCD observations performed in 1995 at the Laborat orio Nacional de Astrof isica at Itajub ai n Brazil. The astrometric reduction is discussed especially the small corrections done here, but most of time neglected elsewhere. A catalog of 6006 dierential positions has been obtained. They have been compared to dierent ephemerides, the Vienne & Duriez ephemerides (TASS 1.7), the Harper & Taylor ephemerides and the Dourneau ephemerides. These observations provide a large set of modern observations, and appear to be of good precision. This accu- racy is needed for future use of these data to improve the dynamical models. These positions are included in the data base NSDC dedicated to the natural satellites (ftp://ftp.bdl.fr/pub/NSDC/saturn/raw data/position/). They are also available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/380/727

Predictions of the mutual events of the Uranian satellites occurring in 2006-2009

Context. Every 42 years, the Earth and the Sun pass through the equatorial plane of Uranus allowing observations of mutual occultations and eclipses of the main satellites of Uranus. The next opportunity will occur in 2006–2009. Aims. Such events are uncommon and very rare, and they allow us to accurately determine the inclinations of the orbits of the satellites, which is usually difficult. However, in order to be able to observe, we need accurate predictions. Methods. To find these predictions, we developed a new dynamical model based on the most recent astrometric observations of the satellites. Results. This paper provides predictions of these events using two different models for the motion of the satellites, along with information useful for the observations. Data on the predictions of the events are available on the web server of the IMCCE at ftp.imcce.fr/pub/ephem/satel/pheura07. Conclusions. We therefore encourage professional and amateur astronomers to join the network of observers to get as many observations as possible.

CCD astrometric observations of Saturnian satellites

Astrometric positions of the first eight largest Saturnian satellites and the Lagrangian satellites Helene, Telesto and Calypso are presented from 493 CCD frames taken at the oppositions in 1995 through 1999. The images were obtained over 27 nights. Observed positions are compared with the calculated ones from Vienne and Duriez TASS 1.7 for the large satellites and from JPL positions for the Lagrangian satellites. The rms is about 0

Astrometric positions for 18 irregular satellites of giant planets from 23 years of observations

farcs

Close encounters of asteroids before and during the ESA GAIA mission

12 for the former but 0

New astrometric measurement and reduction of USNO photographic observations of the main Saturnian satellites: 1974−1998

farcs

The astrometric Gaia-FUN-SSO observation campaign of 99942 Apophis

20 for Iapetus and 0

A project of teaching ground-based astrometry

farcs

A New Consortium: the European Satellite Partnership for Computing Ephemerides (ESPaCE)

28 for Hyperion. For the Lagrangian satellites it is about 0