First stellar occultation by the Galilean moon Europa and upcoming events between 2019 and 2021

Abstract

Context. Bright stellar positions are now known with an uncertainty below 1 mas thanks to Gaia DR2. Between 2019-2020, the Galactic plane will be the background of Jupiter. The dense stellar background will lead to an increase in the number of occultations, while the Gaia DR2 catalogue will reduce the prediction uncertainties for the shadow path. Aims. We observed a stellar occultation by the Galilean moon Europa (J2) and propose a campaign for observing stellar occultations for all Galilean moons. Methods. During a predicted period of time, we measured the light flux of the occulted star and the object to determine the time when the flux dropped with respect to one or more reference stars, and the time that it rose again for each observational station. The chords obtained from these observations allowed us to determine apparent sizes, oblatness, and positions with kilometre accuracy. Results. We present results obtained from the first stellar occultation by the Galilean moon Europa observed on 2017 March 31. The apparent fitted ellipse presents an equivalent radius of 1561.2 $\pm$ 3.6 km and oblatenesses 0.0010 $\pm$ 0.0028. A very precise Europa position was determined with an uncertainty of 0.8 mas. We also present prospects for a campaign to observe the future events that will occur between 2019 and 2021 for all Galilean moons. Conclusions. Stellar occultation is a suitable technique for obtaining physical parameters and highly accurate positions of bright satellites close to their primary. A number of successful events can render the 3D shapes of the Galilean moons with high accuracy. We encourage the observational community (amateurs included) to observe the future predicted events.

arXiv comment10 pages, 16 figures, 4 tables, A&A Letter doi:10.1051/0004-6361/201935500

References in corpus (23)

• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2: The astrometric solution
• A ring system detected around the Centaur (10199) Chariklo
• The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation
• Probing for Evidence of Plumes on Europa with HST/STIS
• Possible ring material around centaur (2060) Chiron
• Quantification of tidal parameters from Solar system data
• Pluto's atmosphere from the 29 June 2015 ground-based stellar occultation at the time of the New Horizons flyby
• Gaia Data Release 1 - The Cepheid & RR Lyrae star pipeline and its application to the south ecliptic pole region
• Pluto's atmosphere from stellar occultations in 2012 and 2013
• Size and shape of Chariklo from multi-epoch stellar occultations
• Study of the plutino object (208996) 2003 AZ84 from stellar occultations: size, shape and topographic features
• On the contribution of PRIDE-JUICE to Jovian system ephemerides
• Pluto's lower atmosphere and pressure evolution from ground-based stellar occultations, 1988-2016
• The structure of Chariklo's rings from stellar occultations
• Results from the 2014 November 15th multi-chord stellar occultation by the TNO (229762) 2007 UK${}_{126}$
• Candidate stellar occultations by large trans-neptunian objects up to 2015
• Astrometry of mutual approximations between natural satellites. Application to the Galilean moons
• Pluto's ephemeris from ground-based stellar occultations (1988-2016)
• A Search for Water Vapor Plumes on Europa using SOFIA
• APPROX -- Mutual approximations between the Galilean moons. The 2016-2018 observational campaign
• New orbits of irregular satellites designed for the predictions of stellar occultations up to 2020, based on thousands of new observations
• Studying Quasar Absorber Host Galaxy Properties Using Image Stacking Technique

Cited by in corpus (9)

• The two rings of (50000) Quaoar
• SORA: Stellar Occultation Reduction and Analysis
• Differential aperture photometry and digital coronagraphy with PRAIA
• Decoupled and coupled moons' ephemerides estimation strategies -- Application to the JUICE mission
• Milliarcsecond astrometry for the Galilean moons using stellar occultations
• Combining astrometry and JUICE -- Europa Clipper radio science to improve the ephemerides of the Galilean moons
• Spacecraft VLBI tracking to enhance stellar occultations astrometry of planetary satellites
• The 2021 mutual phenomena involving the Galilean satellites of Jupiter and the inner satellite Thebe
• Quantification of Tides in Giant Planets from Observations