CCD Astrometric Observations of Phoebe in 2005-2008

International audienceAstrometric observations of Phoebe, the ninth faint satellite of Saturn with vi-sual magnitude of 16.5, were performed during the four successive 2005, 2006, 2007 and 2008 oppositions. A very important amount of 1173 new observed positions of Phoebe, representing more than 50 percent of the observational data available now, were obtained during 30 nights of observation involving six missions, by using three different telescopes. The comparison of our observed positions with the JPL Phoebe ephemeris shows the high quality of our observations, as they appear to be consistent with this ephemeris within only about 50 mas

The PHEMU03 campaign of observation of the mutual events of the Galilean satellites of Jupiter in 2003 at the Bordeaux Observatory

International audienc

The PHEMU03 campaign of observation of the mutual events of the Galilean satellites of Jupiter in 2003 at the Bordeaux Observatory

International audienc

The PHEMU03 campaign of observation of the mutual events of the Galilean satellites of Jupiter in 2003 at the Bordeaux Observatory

International audienc

The Phemu03 campaign of observation of the mutual events of the Galilean satellites of Jupiter in 2003 at the Bordeaux Observatory

This workshop is mainly dedicated to astrometry and photometry of Solar System objects events and to the preparation of future campaigns of observation. Several astronomical studies require a large network of observers in order to acquire enough data of rare phenomena or to observe objects on alert or for a follow-up

Mutual events of Jupiter's satellites observed in 1997 at the Bordeaux Observatory

We present photometric observations of mutual events of the Galilean satellites of Jupiter made in 1997 at the Bordeaux Observatory as part of the international PHEMU97 campaign. We observed 21 events which provided 14 high quality light curves with the CCD camera mounted on the 62 cm telescope. From these curves, we determined observed values and errors for the maximum intensity drop and the time of this light minimum. Phase correction was applied to this time for a proper comparison to theoretical values. Residuals between observed and computed values of both of these parameters have been derived from Arlot's G5 ephemerides. The discussion of errors and residuals shows that these observational parameters generally are so accurately determined that they lead to satellite positions with an angular precision of about ten milliarcseconds, never obtained with classical astrometry. In addition, some theoretical results have been derived from the analysis of our set of observations. The main result concerns the satellite J1 for which our observations of the time of maximum event suggest an advance in longitude of 269 km with respect to G5. Also, for the satellite J4, we similarly obtain a delay of about 170 km which appears to be a real effect

An analysis of Bordeaux meridian transit circle observations of planets and satellites (1997–2007)

Context. Meridian transit circle observations of the planets and their satellites are regularly performed for ephemerides improvement. Some were performed at the Bordeaux observatory during the period 1997–2007. Aims. This paper presents these observations and analyses the data to determine the accuracy of the observations, their interest for dynamical purposes and compares them with the dynamical models of the observed objects. Methods. For the determination of the positions of the planets, the observations of their satellites have been used, providing pseudo observations of the planets. The method is tested. Results. The results show the interest of continuing this type of observation. Residuals show what ephemerides have to be improved using the present data

An analysis of satellite calibration methods for CCD astrometry of Saturn's satellites

This paper presents an analysis of astrometric reduction methods for the calibration of a CCD target. To compare these methods, we collected about 3000 recent CCD observations between 1990-1997. We discuss the comparison of the four main contemporary theories describing the eight major satellites of Saturn, used in recent CCD astrometric reduction. We show that these theories developed by Taylor & Shen ([CITE]), Dourneau ([CITE]), Harper & Taylor ([CITE]) and Duriez & Vienne ([CITE]), give a rather good representation of the orbits of the eight main satellites, especially for satellites III-VI. In the CCD astrometric reduction, we point out a bias of the theories on the derived satellite positions, which can reach about 0 fraction of arcsecond03. Duriez and Vienne's TASS theory ([CITE]), built with significantly higher consistency than the other three, generally leads to the lowest residuals for the observations analysed here. Due to its high quality, we recommend use of this theory for CCD reduction. Systematic errors affecting satellites' derived positions should be small, due to the quality of the TASS theory. This procedure might be an alternative to the multi-theory reduction method previously proposed by Qiao et al. ([CITE]). Observations of satellites obtained from CCD reduction using TASS are expected to be significantly more accurate (0 fraction of arcsecond015) than observations reduced from any other theory (about 0 fraction of arcsecond05)