#ASTROMETRY FOR ASTROPHYSICS PDF PDF#

The reduced error budget for stellar occultations indeed helps to improve the moons' ephemerides, which in turn benefit planetary missions and their science products, such as the recently launched JUICE and upcoming Europa Clipper missions.

Our simulations showed that the proposed tracking and observation experiment can efficiently use synergies between ground- and space-based observations to enhance the science return on both ends. This course will introduce a student to the current understanding of the celestial objects starting from planets to stars to galaxies to the whole Universe. This represents up to an order of magnitude improvement with respect to current solutions and is lower than the stellar occultation error, thus allowing the moon ephemeris solution to fully benefit from the observation. VLBI tracking at Juno's perijove close to a stellar occultation locally (in time) reduces the uncertainty in Jupiter's angular position in the sky to 250-400 m. We identified the most promising observation and tracking opportunities offered by the Juno spacecraft around Jupiter as perfect test cases, for which we ran simulations of our VLBI experiment. On the contrary, the 1960s to 1980s saw an intense development of new or highly improved instruments, including. By no means does this imply that not much progress was made in the ground-based techniques used exclusively until then. We demonstrate the potential of using VLBI to enhance the science return of stellar occultations for satellite ephemerides. The launch of the Hipparcos satellite in 1989 and the Hubble Space Telescope in 1990 revolutionized astrometry. We quantify the local refinement in the central planet's position achievable by performing Very Long Baseline Interferometry (VLBI) tracking of an in-system spacecraft temporally close to an occultation. However, when using these observations in the calculation of satellite ephemerides, the uncertainty in the planetary ephemerides dominates the error budget of the occultation.

We now review the situation for ground-based astrometry, since it is often mistakenly stated that there is no longer any need to pursue ground-based.

#ASTROMETRY FOR ASTROPHYSICS PDF PDF#

Fayolle and 5 other authors Download PDF Abstract:Stellar occultations currently provide the most accurate ground-based measurements of the positions of natural satellites (down to a few kilometres for the Galilean moons). Chapter 1 surveys the opportunities and challenges for astrometry in the twenty-first century (van Altena 2008) while Chapter 2 discusses space satellites primarily designed for astrometry. Download a PDF of the paper titled Spacecraft VLBI tracking to enhance stellar occultations astrometry of planetary satellites, by M.

Astrometry for astrophysics pdf