Observations of the satellite of Neptune

Barnard, E. E.

doi:10.1086/104344

Cited by 5 publications

(2 citation statements)

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“…( 1) and (2). Hall (1911); Hall & Burton (1913); Hall (1920Hall ( , 1922; Burton (1913); Burton & Hall (1919); Bower & Hall (1923) (p, s) 0.716 476 0.312 000 1896-1910Christie (1901; ROG (1899ROG ( , 1900ROG ( , 1903ROG ( , 1904ROG ( , 1905ROG ( , 1906ROG ( , 1907ROG ( , 1908ROG ( , 1913 Barnard (1898Barnard ( , 1899Barnard ( , 1901Barnard ( , 1903Barnard ( , 1906aBarnard ( ,b, 1907Barnard ( , 1909Barnard ( , 1910Barnard ( , 1912Barnard ( , 1913Barnard ( , 1915Barnard ( , 1916Barnard ( , 1917Barnard ( , 1919Barnard ( , 1927 (p, s) 0.757 1100 0.225 084 1899-1923 Kostinsky (1900Kostinsky ( , 1902; Balanovskii (1923) Notes. The data under "Site" are the IAU observatory code.…”

Section: Observationsmentioning

confidence: 99%

The Neptunian gravity estimated from the motion of Triton based on astrometric observations

Wang¹,

Yan²,

Gao³

et al. 2023

A&A

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Context. Accurate gravity and ephemerides estimations for Neptune and its satellites are necessary for the forthcoming deep space exploration missions targeting its system. In addition, these estimations are also meaningful for the modeling of Neptune's interior and for solar system dynamics studies. The body of astrometric data concerning Triton has been accumulating for about two hundred years, but more accurate updates to the ephemerides of this moon and revisions to the relevant gravity parameters would be possible with more precise astrometric data. The new Gaia catalog of star positions plus observations from Voyager 2 and the Hubble Space Telescope provide such a basis for high-precision astrometry and to complement and extend the existing body of data. Aims. We aim to report integrated orbital fits for Triton based on all the available astrometric data from 1847 to 2020, including observations from Earth-based telescopes, Voyager 2, and the Hubble Space Telescope. We also estimate the Neptunian gravity using the motion of Triton. Methods. Triton’s orbital solution was determined by a weighted least-squares method to fit the model to the most complete astrometric data set to date. The DOP853 algorithm was adopted in the numerical integration calculations. For the dynamical model parameters, our orbital model for Triton is similar to the NEP081 but with an update. The perturbations from the inner satellites (Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, and Hippocamp) were considered by adding corrections to J2 and J4 for Neptune. As the gravitational oblateness coefficient of Neptune is correlated with its orientation, the pole parameters were thus kept fixed in the integration when estimating Neptunian gravity. A Monte Carlo analysis was performed, however, to obtain reliable accuracy estimations and to assess the uncertainty of pole parameters on the results’ formal error. Results. We provide a new orbit and dynamical model values for Triton. The estimated accuracy of the model we built and updated fit all the astrometric data. The RMS of the residuals was 0.074 arcsec in the right ascension and 0.071 arcsec in declination. The RMS was 0.102 arcsec for X and 0.139 arcsec for Y in differential coordinates. The RMS for the position angle was 0.834 degrees, and the angular separation distance was 0.257 arcsec for the data collected before 1960. The orbit of Triton was well determined with the orbit differences from NEP081 and NEP097 (so far the latest Triton ephemerides from Jet Propulsion Laboratory) as being less than 300 km (about 15 mas) during the observation coverage period of this study. The large body of astrometric data for Triton over a time interval from 1847 to 2020 was used to constrain its position at the initial epoch, allowing us to reduce formal uncertainty to about 3 km. Based on the most complete weighting astrometric observations of Triton, the estimated mass of the Neptune system is GMs = 6 836 525.210 ±19.526 km3 s−2. Our revised gravity model yields J2 = 3401.655 ±1.850 × 10−6 and J4 = −33.294 ±10.000 × 10−6. The astrometric observations showed little sensitivity to GMs and J4, but acted well on J2. A Monte Carlo method was used to analyze the error caused by a variation in the pole parameters and showed that J2 = 3401.655 ± 3.994 × 10−6 was a more realistic error.

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Section: Observationsmentioning

confidence: 99%

The Neptunian gravity estimated from the motion of Triton based on astrometric observations

Wang¹,

Yan²,

Gao³

et al. 2023

A&A

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“…A&A 641, A108 (2020) Barnard (1906aBarnard ( , 1907Barnard ( , 1909Barnard ( , 1910Barnard ( , 1912Barnard ( , 1913) P,S 972 0.952 0.280 Barnard (1915Barnard ( , 1916Barnard ( , 1917Barnard ( , 1919Barnard ( , 1927…”

Section: Appendix A: Additional Tablesmentioning

confidence: 99%

The orbit of Triton with new precise observations and the INPOP19a ephemeris

Tang

Song

Shen

et al. 2020

A&A

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Aims. The Gaia catalogue brings new opportunities and challenges to high-precision astronomy and astrometry. The precision of data reduction is therefore improved by a large number of reference stars with high-precision positions and proper motions. Numerous precise positions for Triton are obtained from the latest observations using the Gaia catalogue. Furthermore, the new INPOP19a planetary ephemeris, which also fits the observations from the Gaia Data Release 2, has recently become available. In this paper, a new orbit of Triton is calculated using the latest precise charge-coupled device (CCD) observations and the INPOP19a ephemeris. Methods. Triton’s orbital solution is calculated using a numerical integrator, while the orientation of Neptune’s pole in particular is obtained by integrating the simplified Euler’s equations of motion. We determine the orbit of Triton over 170 yr based on 11 040 Earth-based observations made between 1847 and 2016 and on Voyager 2 data. The positions of the Sun and planets are provided by the INPOP19a ephemeris. We compare our results to those from other previous works to check the influences on Triton’s orbit from different planetary ephemerides. Results. A new orbit of Triton is provided here. The root-mean-square of the residuals for the Earth-based CCD absolute observations are 0.102″ in right ascension and 0.142″ in declination. Although most different planetary ephemerides have large differences in Neptune’s position, the orbits of Triton using different planetary ephemerides are still close, under similar dynamical models. The Voyager 2 data add a constraint on Triton’s orbit here.

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New precise positions in 2013–2019 and a catalog of ground-based astrometric observations of 11 Neptunian satellites (1847–2019) based on Gaia-DR2

Yuan

Фан

et al. 2021

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Context. Developing high-precision ephemerides for Neptunian satellites requires not only the continuation of observing campaigns but also the collection and improvement of existing observations. So far, no complete catalogs of observations of Neptunian satellites are available. Aims. We aim to provide new, precise positions, and to compile a catalog including all available ground-based astrometric observations of Neptunian satellites. The observations are tabulated in a single and consistent format and given in the same timescale, the Terrestrial Time (TT), and reference system, the International Celestial Reference System (ICRS), including necessary changes and corrections. Methods. New CCD observations of Triton and Nereid were made at Lijiang 2.4-m and Yaoan 0.8-m telescopes in 2013–2019, and then reduced based on Gaia-DR2. Furthermore, a catalog called OCNS2019 (Observational Catalog of Neptunian Satellites (2019 version)) was compiled, after recognizing and correcting errors and omissions. Furthermore, in addition to what was considered for the COSS08 catalog for eight main Saturnian satellites, all observed absolute and relative coordinates were converted to the ICRS with corrections for star catalog biases with respect to Gaia-DR2. New debiasing tables for both the modern and old star catalogs, which were previously not provided based on Gaia-DR2, are developed and applied. Treatment of missing positions of comparison bodies in conversions of observed relative coordinates are proposed. Results. OCNS2019 and the new debiasing tables are publicly available online. OCNS2019 includes 24996 observed coordinates of 11 Neptunian satellites obtained over 3741 nights from 1847 to 2019. All observations are given in TT and ICRS. The star catalog biases are removed, which are significant for Nereid and outer satellites. We obtained 880 (5% of total now available) new coordinates for Triton over 41 nights (1% of total observation nights so far), and 790 (14%) for Nereid over 47 nights (10%). The dispersions of these new positions are about 0.″03 for Triton and 0.″06 for Nereid. Conclusions. OCNS2019 should be useful in improving ephemerides for the above-mentioned objects.

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Observations of the satellite of Neptune

Cited by 5 publications

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The Neptunian gravity estimated from the motion of Triton based on astrometric observations

The Neptunian gravity estimated from the motion of Triton based on astrometric observations

The orbit of Triton with new precise observations and the INPOP19a ephemeris

New precise positions in 2013–2019 and a catalog of ground-based astrometric observations of 11 Neptunian satellites (1847–2019) based on Gaia-DR2

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