J/A+A/580/A76 Positions of satellites of giant planets (Gomes-Junior+, 2015)
Astrometric positions for 18 irregular satellites of giant planets from 23 years
of observations.
Gomes-Junior A.R., Assafin M., Vieira Martins R., Arlot J.-E.,
Camargo J.I.B., Braga-Ribas F., da Silva Neto D.N., Andrei A.H.,
Dias-Oliveira A., Morgado B.E., Benedetti-Rossi G., Duchemin Y.,
Desmars J., Lainey V., Thuillot W.
<Astron. Astrophys. 580, A76 (2015)>
=2015A&A...580A..76G 2015A&A...580A..76G
ADC_Keywords: Positional data - Solar system
Keywords: planets and satellites: general -
planets and satellites: individual: Jupiter -
planets and satellites: individual: Saturn - astrometry -
Abstract:
The irregular satellites of the giant planets are believed to have
been captured during the evolution of the solar system. Knowing their
physical parameters, such as size, density and albedo is important to
constrain where they came from and how they were captured. The best
way to obtain these parameters are observations in situ by spacecrafts
or from stellar occultations by the objects. Both techniques demand
that the orbits are well known. We aimed to obtain good astrometric
positions of irregular satellites in order to improve their orbits and
ephemeris. We identified and reduced observations of several irregular
satellites from three databases containing more than 8000 images
obtained between 1992 and 2014 at three sites (Observatorio do Pico
dos Dias, Observatoire de Haute-Provence and European Southern
Observatory - La Silla). We used the software PRAIA (Platform for
Reduction of Astronomical Images Automatically) to make the
astrometric reduction of the CCD frames. The UCAC4 catalogue
represented the International Celestial Reference System in the
reductions. The identification of the satellites in the frames was
done through their ephemerides as determined from the SPICE/NAIF
kernels. Some procedures were taken to overcome missing or incomplete
information (coordinates, date), mostly for the older images. We
managed to obtain more than 6000 positions for 18 irregular
satellites, being 12 of Jupiter, 4 of Saturn, 1 of Uranus (Sycorax)
and 1 of Neptune (Nereid). For some satellites the number of obtained
positions is more than 50% of that used in earlier orbital numerical
integrations. Comparison of our positions with recent JPL ephemeris
suggests the presence of systematic errors in the orbits for some of
the irregular satellites. The most evident case was an error in the
inclination of Carme.
Description:
Tables contain the topocentric ICRS coordinates of the irregular
satellites, the position error estimated from the dispersion of the
ephemeris offsets of the night of observation, the UTC time of the
frame's mid-exposure in julian date, the estimated magnitude, the
filter used, the telescope origin and correspondent IAU code. The
filters may be U, B, V, R or I following the Johnson system; C stands
for clear (no filter used), resulting in a broader R band magnitude,
RE for the broad-band R filter ESO#844 with λ=651.725nm and
Δλ=162.184nm (full width at half maximum) and "un" for
unknown filter. E, OH, PE, BC and Z stand respectively for the ESO,
OHP (Observatoire de Haute-Provence), Perkin-Elmer, Bollen & Chivens
and Zeiss telescopes from the Observatorio do Pico dos Dias.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
objects.dat 50 18 List of studied satellites
tables/* . 18 Individual catalogs of positions (1992-2014)
--------------------------------------------------------------------------------
See also:
J/A+A/453/349 : CCD positions for 8 Jovian irregular satellites (Veiga, 2006)
Byte-by-byte Description of file: objects.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Satellite Name
12- 14 I3 --- Num [506/802] IAU code for the satellite
16- 29 A14 --- FileName Name of the file with positions
in subdirectory tables
32- 40 F9.1 d JD.min First observation date
42- 50 F9.1 d JD.max Last observation date
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tables/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 3 I2 h RAh Right ascension (J2000.0)
5- 6 I2 min RAm Right ascension (J2000.0)
8- 14 F7.4 s RAs Right ascension (J2000.0)
16 A1 --- DE- Sign of declination
17- 18 I2 deg DEd Declination (J2000.0)
20- 21 I2 arcmin DEm Declination (J2000.0)
23- 28 F6.3 arcsec DEs Declination (J2000.0)
30- 33 I4 mas e_RAs Right ascension error at mean epoch
35- 38 I4 mas e_DEs Declination error at mean epoch
40- 55 F16.8 d JD Mean epoch (Julian Date) of coordinates
57- 60 F4.1 mag mag Magnitude (apparent) in Filter (1)
62- 63 A2 --- Filt Filter used (2)
65- 66 A2 --- Tel Telescope used (3)
68- 70 I3 --- Site IAU code of the site of observation
--------------------------------------------------------------------------------
Note (1): Estimated magnitude (from PSF fitting) based on filter given in column
Filt. The magnitude errors can be as high as 1mag; they are not photometrically
calibrated and should be used with care.
Note (2): The filters may be U, B, V, R or I following the Johnson system;
C stands for clear (no filter used), resulting in a broader R band magnitude,
RE for the broad-band R filter ESO#844 with λ=651.725nm and
Δλ=162.184nm (full width at half maximum) and
"un" for unknown filter.
Note (3): Telescope code as follows:
E = ESO,
OH = OHP (Observatoire de Haute-Provence),
PE = Perkin-Elmer telescope (Observatorio do Pico dos Dias)
BC = Bollen & Chivens telescope (Observatorio do Pico dos Dias)
Z = Zeiss telescope (Observatorio do Pico dos Dias)
--------------------------------------------------------------------------------
Acknowledgements:
Altair Ramos Gomes-Junior, altair08(at)astro.ufrj.br
(End) A.R. Gomes-Junior [UFRJ/OV, Brazil], P. Vannier [CDS] 15-May-2015