Astrometric results of observations at Russian observatories of mutual occultations and eclipses of Jupiter’s Galilean satellites in 2009

Emelyanov, N. V.; Андреев, М. В.; Berezhnoi, A. A.; Bekhteva, A. S.; Vashkov'yak, S. N.; Velikodskii, Yu. I.; Vereshchagina, I. A.; Gorshanov, D. L.; Devyatkin, A. V.; Izmailov, I. S.; Ivanov, A. V.; Irsmambetova, T. R.; Козлов, В. А.; Karashevich, S. V.; Kurenya, A. N.; Naiden, Ya. V.; Naumov, K. N.; Parakhin, N.; Raskhozhev, V. N.; Selyaev, S. A.; Сергеев, А. В.; Sokov, E.; Khovrichev, M. Yu.; Khrutskaya, E. V.; Chernikov, M. M.

doi:10.1134/s0038094611010035

Cited by 9 publications

(3 citation statements)

References 17 publications

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“…Another way to obtain very precise relative positions of typically a few mas is with the observation of mutual phenomena. However this can only be done during the equinox of these planets -see for example Assafin et al (2009); Emelyanov (2009); Emelyanov et al (2011); Dias-Oliveira et al (2013); Arlot et al (2014). Mutual phenomena consist of occultations and eclipses between natural satellites, as seen along the line of sight of an observer.…”

Section: Introductionmentioning

confidence: 99%

Astrometry of mutual approximations between natural satellites. Application to the Galilean moons

Morgado

Assafin

Vieira-Martins

et al. 2016

Mon. Not. R. Astron. Soc.

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Typically we can deliver astrometric positions of natural satellites with errors in the 50-150 mas range. Apparent distances from mutual phenomena, have much smaller errors, less than 10 mas. However, this method can only be applied during the equinox of the planets. We developed a method that can provide accurate astrometric data for natural satellites -the mutual approximations. The method can be applied when any two satellites pass close by each other in the apparent sky plane. The fundamental parameter is the central instant t 0 of the passage when the distances reach a minimum.We applied the method for the Galilean moons. All observations were made with a 0.6 m telescope with a narrow-band filter centred at 889 nm with width of 15 nm which attenuated Jupiter's scattered light. We obtained central instants for 14 mutual approximations observed in 2014-2015. We determined t 0 with an average precision of 3.42 mas (10.43 km). For comparison, we also applied the method for 5 occultations in the 2009 mutual phenomena campaign and for 22 occultations in the 2014-2015 campaign. The comparisons of t 0 determined by our method with the results from mutual phenomena show an agreement by less than 1-sigma error in t 0 , typically less than 10 mas. This new method is particularly suitable for observations by small telescopes.

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Section: Introductionmentioning

confidence: 99%

Astrometry of mutual approximations between natural satellites. Application to the Galilean moons

Morgado

Assafin

Vieira-Martins

et al. 2016

Mon. Not. R. Astron. Soc.

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“…The 89 lightcurves were processed with the procedure explained in the present paper. A description of this series of observations and obtained astrometric results was published in Emelyanov et al (2011).…”

Section: The Phemu09 Campaignmentioning

confidence: 99%

The PHEMU21 catalogue and astrometric results of the observations of the mutual occultations and eclipses of the Galilean satellites of Jupiter made in 2021

Emelyanov

Arlot

Anbazhagan

et al. 2022

Monthly Notices of the Royal Astronomical Society

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2021 was the year of Jupiter’s equinox, that is the Sun and the Earth passed through the equatorial plane of the planet and therefore the orbital planes of its main satellites. This occurrence made it possible to observe mutual occultations and eclipses between the satellites. Our former experience shows that observations of such events provide accurate astrometric data that can be used to obtain new information on the dynamics of the Galilean satellites. The observations are a series of photometric measurements of a satellite which are carried out through the organization of a world wide campaign of observations thus maximizing the number and the quality of the data obtained. This work focuses on processing the photometric observations of the mutual occultations and eclipses of the Galilean satellites of Jupiter made during the international campaign in 2021. The final goal is to derive new accurate astrometric data. We used an accurate photometric model of mutual events in conjunction with the accuracy of observation. We obtained and processed the 84 light curves obtained during the campaign. As compared with the current best ephemerides, the rms of ’O-C’ residuals are equal to 49 and 48 mas in right ascension and declination, respectively.

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“…Alternatively, the relative position of two satellites can also be precisely measured by observing mutual events -occultations or eclipses (e.g. Emelyanov 2009;Emelyanov et al 2011;Dias-Oliveira et al 2013;Arlot et al 2014). During mutual events, one satellite masks the other, resulting in a drop of the flux received by the observer.…”

Section: Introductionmentioning

confidence: 99%

Analytical framework for mutual approximations

Fayolle

Dirkx

Visser

et al. 2021

A&A

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Context. The apparent close encounters of two satellites in the plane of the sky, called mutual approximations, have been suggested as a different type of astrometric observation to refine the moons’ ephemerides. The main observables are then the central instants of the close encounters, which have the advantage of being free of any scaling and orientation errors. However, no analytical formulation is available yet for the observation partials of these central instants, leaving numerical approaches or alternative observables (i.e. derivatives of the apparent distance instead of central instants) as options. Aims. Filling that gap, this paper develops an analytical method to include central instants as direct observables in the ephemerides estimation and assesses the quality of the resulting solution. Methods. To this end, the apparent relative position between the two satellites is approximated by a second-order polynomial near the close encounter. This eventually leads to an expression for mutual approximations’ central instants as a function of the apparent relative position, velocity, and acceleration between the two satellites. Results. The resulting analytical expressions for the central instant partials were validated numerically. In addition, we ran a covariance analysis to compare the estimated solutions obtained with the two types of observables (central instants versus alternative observables), using the Galilean moons of Jupiter as a test case. Our analysis shows that alternative observables are almost equivalent to central instants in most cases. Accurate individual weighting of each alternative observable, accounting for the mutual approximation’s characteristics (which are automatically included in the central instants’ definition), is however crucial to obtain consistent solutions between the two observable types. Using central instants still yields a small improvement of 10–20% of the formal errors in the radial and normal directions (RSW frame), compared to the alternative observables’ solution. This improvement increases when mutual approximations with low impact parameters and large impact velocities are included in the estimation. Conclusions. Choosing between the two observables thus requires careful assessment, taking into account the characteristics of the available observations. Using central instants over alternative observables ensures that the state estimation fully benefits from the information encoded in mutual approximations, which might be necessary depending on the application of the ephemeris solution.

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Astrometric results of observations at Russian observatories of mutual occultations and eclipses of Jupiter’s Galilean satellites in 2009

Cited by 9 publications

References 17 publications

Astrometry of mutual approximations between natural satellites. Application to the Galilean moons

Astrometry of mutual approximations between natural satellites. Application to the Galilean moons

The PHEMU21 catalogue and astrometric results of the observations of the mutual occultations and eclipses of the Galilean satellites of Jupiter made in 2021

Analytical framework for mutual approximations

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