J/A+A/582/A8 Astrometry of the main satellites of Uranus (Camargo+, 2015)
Astrometry of the main satellites of Uranus: 18 years of observations.
Camargo J.I.B., Magalhaes F.P., Assafin M., Braga-Ribas F.,
Dias-Oliveira A., Benedetti-Rossi G., Gomes-Junior A.R., Andrei A.H.,
da Silva Neto D.N.
<Astron. Astrophys. 582, A8 (2015)>
=2015A&A...582A...8C 2015A&A...582A...8C (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Positional data
Keywords: astrometry - methods: data analysis - catalogs -
planets and satellites: individual: Uranus
Abstract:
We determine accurate positions of the main satellites of Uranus:
Miranda, Ariel, Umbriel, Titania, and Oberon. Positions of Uranus, as
derived from those of these satellites, are also determined. The
observational period spans from 1992 to 2011. All runs were made at
the Pico dos Dias Observatory, Brazil.
We used the software called Platform for Reduction of Astronomical
Images Automatically (PRAIA) to perform a digital coronography to
minimise the influence of the scattered light of Uranus on the
astrometric measurements and to determine accurate positions of the
main satellites. The positions of Uranus were then indirectly
determined by computing the mean differences between the observed and
ephemeris positions of these satellites. A series of numerical filters
was applied to filter out spurious data. These filters are mostly
based on (a) the comparison between the positions of Oberon with those
of the other satellites and on (b) the offsets as given by the
differences between the observed and ephemeris positions of all
satellites.
We have, for the overall offsets of the five satellites, -29mas
(±63mas) in right ascension and -27mas (±46mas) in declination.
For the overall difference between the offsets of Oberon and those of
the other satellites, we have +3mas (±30mas) in right ascension
and -2mas (±28mas) in declination. Ephemeris positions for the
satellites were determined from DE432+ura111.
Description:
Positions of the main satellites of Uranus - Miranda, Ariel, Umbriel,
Titania, and Oberon, are presented. Positions of Uranus, as derived
from those of the satellites, are also presented. Note that these
positions of Uranus are not observed ones. Also, as requested by the
editor of A&A, the X,Y coordinates on the CCD of the observed
satellites and reference stars are given.
To extend the time span of our observations to older epochs, positions
from Veiga et al. (2003AJ....125.2714V 2003AJ....125.2714V, hereafter V03) for the main
satellites are provided. In the same way as mentioned above, positions
of Uranus were determined. Note that no X,Y coordinates are given to
the positions from V03 because the raw data was unfortunately lost.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ariel_j.dat 55 1710 Observed positions of Ariel
miran_j.dat 55 584 Observed positions of Miranda
obero_j.dat 55 2928 Observed positions of Oberon
titan_j.dat 55 2588 Observed positions of Titania
umbri_j.dat 55 1987 Observed positions of Umbriel
uranu_j.dat 62 3516 Positions of Uranus (indirectly determined
from those of the satellites)
ariel_v.dat 75 474 Observed positions of Ariel from V03
miran_v.dat 75 476 Observed positions of Miranda from V03
obero_v.dat 75 732 Observed positions of Oberon from V03
titan_v.dat 75 558 Observed positions of Titania from V03
umbri_v.dat 75 462 Observed positions of Umbriel from V03
uranu_v.dat 80 732 Positions of Uranus (indirectly determined
from those of the satellites) from V03
ariel_xy.dat 34 1710 *CCD X,Y coordinates for Ariel
miran_xy.dat 34 584 *CCD X,Y coordinates for Miranda
obero_xy.dat 34 2928 *CCD X,Y coordinates for Oberon
refst_xy.dat 34 43413 *CCD X,Y coordinates for reference stars
titan_xy.dat 34 2588 *CCD X,Y coordinates for Titania
umbri_xy.dat 34 1987 *CCD X,Y coordinates for Unbriel
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Note on *xy.dat: These CCD coordinates profit from the digital coronography
procedure applied on the images to attenuate the influence of the scattered
light of Uranus on the astrometry of the satellites and stars.
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See also:
J/A+AS/130/77 : Astrometry of satellites of Uranus (Jones+ 1998)
Byte-by-byte Description of file: *_j.dat
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Bytes Format Units Label Explanations
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1- 16 F16.8 d JD UTC instant of the satellite position (JD)
20- 21 I2 h RAh Right ascension (J2000) of satellite at date
23- 24 I2 min RAm Right ascension (J2000) of satellite at date
26- 31 F6.3 s RAs Right ascension (J2000) of satellite at date
34 A1 --- DE- Declination sign (J2000) of satellite at date
35- 36 I2 deg DEd Declination (J2000) of satellite at date
38- 39 I2 arcmin DEm Declination (J2000) of satellite at date
41- 45 F5.2 arcsec DEs Declination (J2000) of satellite at date
49- 51 I3 mas e_RAs Error in RA (J2000) at date (1)
53- 55 I3 mas e_DEs Error in DE (J2000) at date
59- 62 A4 --- Sat Satellites that contributed to the
determination of the position of Uranus
(ONLY for uranus_j.dat) (G1)
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Note (1): This value was multiplied by the cosine of the declination
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Byte-by-byte Description of file: *_v.dat
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Bytes Format Units Label Explanations
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1- 15 F15.7 d JD UTC instant of the satellite position (JD)
19- 20 I2 h RAh Right ascension (J2000) of satellite at date (1)
22- 23 I2 min RAm Right ascension (J2000) of satellite at date (1)
25- 31 F7.4 s RAs Right ascension (J2000) of satellite at date (1)
34 A1 --- DE- Declination sign (J2000) of satellite at date
35- 36 I2 deg DEd Declination (J2000) of satellite at date (1)
38- 39 I2 arcmin DEm Declination (J2000) of satellite at date (1)
41- 47 F7.4 arcsec DEs Declination (J2000) of satellite at date (1)
51- 53 I3 mas e_RAs Right ascension uncertainty (J2000) at date (2)
55- 57 I3 mas e_DEs Declination uncertainty (J2000) at date
63- 66 I4 mas RAtop Right ascension geocentric to topocentric (2) (3)
72- 75 I4 mas DEtop Declination geocentric to topocentric (3)
77- 80 A4 --- Sat Satellites that contributed to the
determination of the position of Uranus
(ONLY for uranus_v.dat) (G1)
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Note (1): These are geocentric coordinates, as originally provided by
Veiga et al. (2003AJ....125.2714V 2003AJ....125.2714V, V03).
Note (2): This value was multiplied by the cosine of the Declination.
Note (3): This value should be added to the respective coordinate (RA or DEC)
to convert it from geocentric to topocentric (Pico dos Dias Observatory, IAU
code 874) coordinate.
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Byte-by-byte Description of file: *_xy.dat
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Bytes Format Units Label Explanations
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2- 8 F7.2 pix Xpix CCD X coordinate of centroid (1)
10- 16 F7.2 pix Ypix CCD Y coordinate of centroid (1)
19- 34 F16.8 d JD UTC instant of the position (JD)
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Note (1): These CCD coordinates profit from the digital coronography procedure
applied on the images to attenuate the influence of the scattered light of
Uranus on the astrometry of the satellites and stars.
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Global notes:
Note (G1): ONLY for uranus (uranu_j.dat and uranus_v.dat).
First letter of the satellites whose positions were used in the
determination of the position of Uranus: 'a' - Ariel, 'u' - Umbriel,
't' - Titania, 'o' - Oberon. Miranda was not used.
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Acknowledgements:
Julio Camargo, camargo(at)on.br
(End) Julio Camargo [ON/MCTI, Brazil], Patricia Vannier [CDS] 24-Sep-2015