APPROX — Mutual approximations between the Galilean moons. The 2016-2018 observational campaign. (arXiv:1811.02913v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Morgado_B/0/1/0/all/0/1">B. Morgado</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vieira_Martins_R/0/1/0/all/0/1">R. Vieira-Martins</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Assafin_M/0/1/0/all/0/1">M. Assafin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Machado_D/0/1/0/all/0/1">D. I. Machado</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Camargo_J/0/1/0/all/0/1">J. I. B. Camargo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sfair_R/0/1/0/all/0/1">R. Sfair</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Malacarne_M/0/1/0/all/0/1">M. Malacarne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Braga_Ribas_F/0/1/0/all/0/1">F. Braga-Ribas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Robert_V/0/1/0/all/0/1">V. Robert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bassallo_T/0/1/0/all/0/1">T. Bassallo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Benedetti_Rossi_G/0/1/0/all/0/1">G. Benedetti-Rossi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boldrin_L/0/1/0/all/0/1">L. A. Boldrin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Borderes_Motta_G/0/1/0/all/0/1">G. Borderes-Motta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Camargo_B/0/1/0/all/0/1">B. C. B. Camargo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Crispim_A/0/1/0/all/0/1">A. Crispim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dias_Oliveira_A/0/1/0/all/0/1">A. Dias-Oliveira</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gomes_Junior_A/0/1/0/all/0/1">A. R. Gomes-Júnior</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lainey_V/0/1/0/all/0/1">V. Lainey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miranda_J/0/1/0/all/0/1">J. O. Miranda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moura_T/0/1/0/all/0/1">T. S. Moura</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ribeiro_F/0/1/0/all/0/1">F. K. Ribeiro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Santana_T/0/1/0/all/0/1">T. de Santana</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Santos_Filho_S/0/1/0/all/0/1">S. Santos-Filho</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Trabuco_L/0/1/0/all/0/1">L. L. Trabuco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Winter_O/0/1/0/all/0/1">O. C. Winter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yamashita_T/0/1/0/all/0/1">T. A. R. Yamashita</a>
The technique of mutual approximations accurately gives the central instant
at the maximum apparent approximation of two moving natural satellites in the
sky plane. This can be used in ephemeris fitting to infer the relative
positions between satellites with high precision. Only the mutual phenomena —
occultations and eclipses — may achieve better results. However, mutual
phenomena only occur every six years in the case of Jupiter. Mutual
approximations do not have this restriction and can be observed at any time
along the year as long as the satellites are visible. In this work, we present
104 central instants determined from the observations of 66 mutual
approximations between the Galilean moons carried out at different sites in
Brazil and France during the period 2016–2018. For 28 events we have at least
two independent observations. All telescopes were equipped with a narrow-band
filter centred at 889 nm with a width of 15 nm to eliminate the scattered light
from Jupiter. The telescope apertures ranged between 25–120 cm. For
comparison, the precision of the positions obtained with classical CCD
astrometry is about 100 mas, for mutual phenomena it can achieve 10 mas or less
and the average internal precision obtained with mutual approximations was 11.3
mas. This new kind of simple, yet accurate observations can significantly
improve the orbits and ephemeris of Galilean satellites and thus be very useful
for the planning of future space missions aiming at the Jovian system.
The technique of mutual approximations accurately gives the central instant
at the maximum apparent approximation of two moving natural satellites in the
sky plane. This can be used in ephemeris fitting to infer the relative
positions between satellites with high precision. Only the mutual phenomena —
occultations and eclipses — may achieve better results. However, mutual
phenomena only occur every six years in the case of Jupiter. Mutual
approximations do not have this restriction and can be observed at any time
along the year as long as the satellites are visible. In this work, we present
104 central instants determined from the observations of 66 mutual
approximations between the Galilean moons carried out at different sites in
Brazil and France during the period 2016–2018. For 28 events we have at least
two independent observations. All telescopes were equipped with a narrow-band
filter centred at 889 nm with a width of 15 nm to eliminate the scattered light
from Jupiter. The telescope apertures ranged between 25–120 cm. For
comparison, the precision of the positions obtained with classical CCD
astrometry is about 100 mas, for mutual phenomena it can achieve 10 mas or less
and the average internal precision obtained with mutual approximations was 11.3
mas. This new kind of simple, yet accurate observations can significantly
improve the orbits and ephemeris of Galilean satellites and thus be very useful
for the planning of future space missions aiming at the Jovian system.
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