The 2014–2015 Brazilian mutual phenomena campaign for the Jovian satellites and improved results for the 2009 events☆
Introduction
Mutual phenomena between natural satellites – occultations and eclipses – have been successfully used to improve the orbital studies of these moons. For the Galilean satellites, they have been systematically observed since 1976 (Aksnes and Franklin, 1976). These phenomena occur as the Earth and the Sun cross the orbital plane of the satellites. For Jupiter, they happen every six years.
The photometry of these events offers a reliable source of very precise relative positions between two satellites. They often achieve uncertainties bellow 5 mas ( 15 km) (Emelyanov, 2009; Dias-Oliveira et al., 2013; Arlot et al., 2014a; Saquet et al., 2018). These relative positions can constrain the orbital studies of these moons and give us hints about their structure and formation processes (Lainey et al., 2004b; a, 2009, 2017).
The uncertainty of the positions obtained from mutual phenomena is usually smaller than the ones obtained by other methods. For instance, classical CCD astrometry achieves uncertainties around 100 mas ( 300 km) (Kiseleva et al., 2008). For satellite-pair distances, the uncertainties are at the 30 mas level ( 90 km) (Peng et al., 2012). Mutual approximations, based in the same geometrical configuration of mutual occultations, achieve uncertainties at the 10 mas level ( 30 km) (Morgado et al., 2016, 2019).
In this paper, we present results for 47 light curves, 31 occultations and 16 eclipses, representing 40 mutual events between the Galilean moons observed by three stations in Brazil, during the 2014–2015 mutual phenomena campaign. We also present one event, an eclipse involving the inner satellite Amalthea (J5). We also used our improved methods to re-analyse 25 light curves, 13 occultations and 12 eclipses, of 25 mutual phenomena observed by our group during the 2009 mutual phenomena campaign. We compared the new results with those by Dias-Oliveira et al. (2013), Arlot et al. (2014a) and Morgado et al. (2016).
In Section 2 we detail the observational campaigns. In Section 3 we present the photometry used to produce the observed light curves and describe the new, improved light-curve fitting procedures developed and used in this work. Section 4.1 contains new results from the re-analysis of 25 mutual events observed in 2009 and the comparison with the older results. In Section 4.2, we present the results for the 47 light curves involving 40 mutual events observed from Brazil during the 2014–2015 campaign. In Section 4.3, we present the result for the eclipse involving Amalthea. Our conclusions are set on Section 5.
Section snippets
Mutual phenomena campaign details
Every six years, during Jupiter equinox, we can observe mutual occultations and eclipses between Jupiter’s regular satellites. The results presented here come from the collaboration between five Brazilian institutes. The prediction of these events was provided by the Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE)1 (Arlot et al., 2014a, b).
The 2009 mutual phenomena campaign was the first large attempt of the kind carried
Light curve analysis
In mutual phenomena, one can determine relative positions between the satellites through the analysis of the events’ light curves. In our procedure, we simulate theoretical light curves and use them to fit the observed ones.
The parameters of interest are: (i) the impact parameter (), the smallest apparent angular distance in the sky plane between both satellite’s centres in the case of occultations or between the eclipsed satellite centre and the centre of the eclipsing shadow in the sky
Re-analysis of the mutual phenomena between the Galilean moons - 2009
From April to October of 2009, 25 light curves for 25 mutual events between the Galilean moons, 13 occultations and 12 eclipses, were observed by our group with the 60 cm Zeiss telescope of the Observatório Pico dos Dias (OPD) using the methane filter. These events were analysed by Dias-Oliveira et al. (2013) and by Arlot et al. (2014a). However, the results obtained by both presented a significant difference (higher than ).
More recently, Morgado et al. (2016) analysed 5 mutual approximations
Conclusions
We presented in this paper the results for 40 mutual events from the observation and analysis of 47 light curves, 31 occultations and 16 eclipses, obtained during the 2014–2015 mutual phenomena campaign between the Galilean satellites. The observations were made at three stations in the South and South-East of Brazil, using telescopes with diameters ranging between 28 and 60 cm. We also obtained updated results from the re-analysis of 25 mutual events, 13 occultations and 12 eclipses, observed
Acknowledgements
We thank our anonymous referee and N. Emelyanov for helpful comments. This study was financed by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. Part of this research is suported by INCT do e-Universo, Brazil (CNPQ grants 465376/2014-2). BM thanks the CAPES/Cofecub-394/2016-05 grant. RVM acknowledges the grants: CNPq-304544/2017-5, 401903/2016-8, Capes/Cofecub-2506/2015, FAPERJ: PAPDRJ-45/2013 and E-26/203.026/2015. MA thanks CNPq (Grants
References (43)
- et al.
Natural satellites mutual phenomena observations: Achievements and future
Planet. Space Sci.
(2019) - et al.
Instrumental and digital coronagraphy for the observation of the Uranus satellites’ upcoming mutual events
Planet. Space Sci.
(2008) Bidirectional reflectance spectroscopy 3. Correction for macroscopic roughness
Icarus
(1984)Bidirectional reflectance spectroscopy 4. The extinction coefficient and the opposition effect
Icarus
(1986)Bidirectional reflectance spectroscopy. 5. The coherent backscatter opposition effect and anisotropic scattering
Icarus
(2002)Bidirectional reflectance spectroscopy. 6. Effects of porosity
Icarus
(2008)Bidirectional reflectance spectroscopy 7. The single particle phase function hockey stick relation
Icarus
(2012)Spectrophotometry of the Jovian planets and titan at 300- to 1000-nm wavelength: the methane spectrum
Icarus
(1994)Methane, ammonia, and temperature measurements of the jovian planets and titan from CCD-spectrophotometry
Icarus
(1998)- et al.
New constraints on Saturn’s interior from Cassini astrometric data
Icarus
(2017)
The small inner satellites of jupiter
Icarus
Mutual phenomena of the Galilean satellites in 1973. III. Final results from 91 light curves
Astron. J.
The PHEMU09 catalogue and astrometric results of the observations of the mutual occultations and eclipses of the Galilean satellites of Jupiter made in 2009
Astron. Astrophys.
The Phemu 2015 campaign of observations of the mutual events of the Galilean satellites of Jupiter
Natural satellites astrometric data from either space probes and ground-based observatories produced by the European consortium “ESPaCE”
Notes Scientifiques et Techniques de l’Institut de Mecanique Celeste
Observations and analysis of mutual events between the uranus main satellites
Astron. J.
Praia - platform for reduction of astronomical images automatically
Image reduction and analysis facility development
Kitt Peak National Observatory Newsletter
Observational detection of eclipses of J5 Amalthea by the Galilean satellites
Astron. Astrophys.
Analysis of 25 mutual eclipses and occultations between the Galilean satellites observed from Brazil in 2009
Mon. Not. R. Astron. Soc.
Current problems of dynamics of moons of planets and binary asteroids based on observations
Sol. Syst. Res.
Cited by (0)
- ☆
Based in part on observations made at the Laboratório Nacional de Astrofísica (LNA), Itajubá-MG, Brazil.