The Natural satellite database of the Main Astronomical
Observatory of the National Academy of Sciences of
Ukraine. An overview
Irina Kulyk, Yelena Yizhakevych, Lyudmila Pakuliak
To cite this version:
Irina Kulyk, Yelena Yizhakevych, Lyudmila Pakuliak. The Natural satellite database of the
Main Astronomical Observatory of the National Academy of Sciences of Ukraine. An overview.
IMCCE. International Workshop NAROO-GAIA ”A new reduction of old observations in the
Gaia era”, Paris Observatory, Jun 2012, Paris, France. pp. 153-158, 2013.
HAL Id: hal-00758312
http://hal.upmc.fr/hal-00758312
Submitted on 7 May 2013
HAL is a multi-disciplinary open access
archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d’enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.
The Natural satellite database of the Main Astronomical Observatory of the National Academy of Sciences of Ukraine. An overview
Irina Kulyk, Yelena Yizhakevych, Lyudmila Pakuliak
Main Astronomical Observatory NASU, Kyiv, Ukraine, [email protected]
Introduction
The dynamical studies and development of new ephemerides require astrometric observations covering
long time intervals. The current progress in the accuracy of astrometric catalogues provided by space
missions and development of new approaches for extracting information bring new challenges to derive
high precision astrometric positions from photographic plates collected during earlier epochs. The
more than 40-year long observational activity (1949-1990) at the Main Astronomical Observatory of the
National Academy of Sciences of Ukraine (Golosiiv) led to the accumulation of about 1800 photographic plates with images of planets and their satellites. 11 instruments at 9 observational sites were involved in the observations, however, the bulk of the data were obtained with two telescopes: The Tepfer
Double Long-Focus Astrograph (D=400mm, F=5500mm) and the Zeiss Double Wide-Angle Astrograph
(D=400mm, F=2200mm), both of them were located at Golosiiv. The 60-cm ZEISS Reflector (D=600
mm, F=7500mm) located at the high-altitude observational station on Mount Maidanak (Uzbekistan)
was also intensively used for the observations of solar system objects during the period of 1986-1990.
The basic characteristics of the telescopes and the plate parameters are presented in Table 1.
Table 1. Basic parameters of the instrumentations
Telescope
Tube
Double Long
Focus Astrograph (DLA)
DLA
Zeiss Double
Wide-Angle
Astrograph
(DWA)
DWA
1
Field of Plate size Plate scale Color
view
in mm
in ʺ/mm
band
2.5x2.5º 240x240
38.47
Bph
2
1
1.8X2.5
8.0x8.0
160x240
300x300
38.47
103.13
Vph
Bph
NP27
ORWO
ZU21
1976-1989
2
8.0x8.0
300x300
103.13
Bph
0.5x0.5
90x120
27.50
ORWO
ZU21
ORWO
ZU21,ZU2,
NP27
1986-1990
60-cm ZEISS
Reflector
Emulsion
ORWO
ZU21 ZU2
Period of
observations
1949-1984
The numbers of photographic plates with images of solar system objects are listed in Table 2. In the first
period the main objective of the investigation was to improve the ephemerides of the planets. Therefore,
different techniques were used in order to decrease the brightness difference between the images of the
planets and the reference stars on the plates. The images of the satellites, except those of Deimos, were
a sort of ‘by-product’ to some extent and therefore the quality of the images of these satellites is not
153
always good enough to be processed. In some cases, for example, satellite images are either too faint
due to a too short exposure time or being too close to the planet. Nevertheless, about 800 astrometric
positions of the Saturnian satellites, 400 positions of the satellites of Mars, and 30 positions of the external satellites of Jupiter were extracted (Sereda et al., 1978; Yizhakevich et al., 1991; Yizhakevich et al.,
1994; Yizhakevich et al., 2001).
Table 2. Statistics of the observations
Telescope
DLA
DWA
60-cm ZEISS
(Maidanak )
Object
Time span
Mars
Jupiter
Saturn
Jupiter
Saturn
Uranus, Neptune,
Pluto
Phobos
Deimos
S2-S8
U1-U4
JVI-JVIII
1956-1984
1958-1984
1960-1984
1976-1988
1976-1988
1977-1989
Number of
plates
590
310
200
120
70
60
1986, 1988
1986, 1988
1990
1990
1987-1989
130
200
230
58
24
Other objects on
the plates
Deimos
Galilean satellites
S2-S8
Galilean satellites
S6, S8
U3-U4
Reduction of the observations
The oldest plates obtained were measured with the semi-automatic coordinate- measuring machine
‘ASCORECORD’. The measured positions were originally obtained in the system of the Yale, AGK3,
SAO, or PPM catalogues. Later the astrometric positions of the satellites were re-reduced with the ACT
catalogue (Urban et al., 1997) using either the original measurements or the published dependences of
the reference stars.
The images of the major Saturnian moons, which were obtained with the Golosiiv telescopes, were
measured with the automatic coordinate-measuring machine ‘PARSEC’. The astrometric positions of
the satellites were derived using the ACT catalogue. The obtained positions were compared with the
theoretical positions provided by the IMCCE (Dourneau, 1993; Harper and Taylor, 1993; Vienne and
Duriez, 1995) as well as the JPL ephemeris SAT339 (Jacobson, 2010, http://ssd.jpl.nasa.gov).
To process the data on the satellites of Saturn and Uranus obtained with the 60-cm Zeiss reflector at the
1990 opposition, a special catalogue of the secondary reference stars was made using the wide-angle
field plates obtained at the same epochs as those of the satellites observations. All plates were measured
with the ‘ASCORECORD’ and the ACT and Tycho-2 catalogues provided the reference stars. The positions of the satellites were compared with the JPL ephemerides (Giorgini et al., 1996).
The plates of the outer satellites of Jupiter were obtained with the 60-cm Zeiss reflector and Double
wide-angle astrograph. All plates were measured with ‘ASCORECORD’ and reduced using the AGK3
and PPM star catalogues. The comparison with the modern ephemerides was not done.
154
Statistics of the observations and astrometric positions of the satellites of Mars, Saturne
and Uranus
Deimos and Phobos. The histograms of the measured astrometric positions of Deimos and Phobos as a
function of time are presented in Fig.1 and 2 respectively.
Fig1.Histograms of of the observations of Deimos
Fig.2 Histograms of of the observations of Phobos
All derived positions were compared with the ephemerides to evaluate the accuracy of the observations.
The statistics of the comparison with JPL ephemerides is shown in Table 3, where the mean (O-C)
values and their root-mean-square errors are presented. Some of the observed positions, which residuals
were larger than 2σ, were rejected. The table shows that the scatter of the observed positions around the
means is large enough for both satellites. There is a considerable bias between the measured and ephemeris positions of Deimos for the period of 1960-1980.
Table 3. Statistics of the (O-C) of Deimos and Phobos
Object
Deimos
Phobos
Telescope
(O-C)α×cos(δ)
DLFA
-0.22ʺ
60-cm Zeiss
0.04
60-cm Zeiss
0.06
rmsα
±0.50ʺ
0.40
0.50
(O-C)δ
0.34ʺ
0.13
0.09
rmsδ
±0.50ʺ
0.30
0.31
N
127
115
112
The root-mean-square errors of the residuals of the reference ACT stars are 0.23ʺ and 0.30ʺ in right
ascension and declination respectively, which characterizes the accuracy of the measurements and of
the used reference star.
Saturn’s satellites. The histograms of the measured astrometric positions of Tethys, Dione, Rhea, Titan,
and Iapetus are presented in Figs. 3-8.
155
Fig. 3 Histogram of the observations of Enceladus
Fig. 4 Histogram of the observations of Tethys
Fig. 5 Histogram of the observations of Dione
Fig.6 Histogram of the observations of Rhea
Fig. 7 Histogram of the observations of Titan
Fig.8 Histogram of the observations of Iapetus
According to Harper and Taylor (1994) and Dourneau (1993) there are considerable gaps in the observation coverage for all the satellites of Saturn. For example, no published observations are available
between 1948 and 1966, only the observations made at the Bordeaux observatory since 1967 were
published. Therefore, the plates obtained between 1960 and 1970 in Golosiiv, may be of special interest
to add to the world-wide database of the satellite observations.
The reduction of the plates was made with the ACT catalogue as reference. The root-mean-square errors
of the residuals of the reference stars were about 0.3ʺ. In order to estimate the accuracy of the derived
satellite positions avoiding the influence of the star catalogue, the inter-satellite differences were calculated. Titan was chosen as a reference satellite because its image appeared on most of the plates. The
156
statistics of the inter-satellite differences are listed in Table 4. Here the mean differences Δα×cos(δ) and
Δδ with their errors are presented. The outliers, whose residuals were more than 1.0ʺ, were rejected.
Satellite
S2-S6
S3-S6
S4-S6
S5-S6
S8-S6
Table 4. Statistics of the inter-satellite differences of the main
Saturnian satellites with respect to S6 Titan
Δα×cos(δ)
σα
Δδ
σδ
N
Reference stars
σα
σδ
-0.06ʺ
±0.07ʺ
-0.08ʺ
±0.07ʺ
18
0.31ʺ
0.28ʺ
0.11
0.03
-0.06
0.03
50
0.19
0.18
0.02
0.02
-0.08
0.02
88
0.22
0.20
-0.05
0.02
-0.04
0.02
161
0.21
0.19
-0.02
0.02
0.08
0.02
119
0.23
0.26
Saturnian and Uranian satellites at 1990 opposition. About 230 astrometric positions of the eight major
Saturnian satellites and 58 of the Uranian moons Ariel, Umbriel, Titania, Oberon were obtained from
41 photographic plates taken with 0.6m Zeiss reflector in 1990 at Mount Maidanak. As it has been
mentioned above, a catalogue of secondary reference stars was constructed using wide-field plates and
the reference Tycho-2 catalogue. The mean root-mean square errors of the residuals of the secondary
reference stars varied from 0.12 to 0.16ʺ for both coordinates.
Brief conclusions
The Golosiiv Plate Archive contains about 300 photographic plates with images of Deimos and Phobos,
about 250 plates of Saturn and its main satellites, about 60 plates of the Uranian satellites and 24 plates
with images of the outer satellites of Jupiter.
Previous re-reduction of Mars’ and Saturn’ satellites in the reference system of the ACT astrometric
catalogue revealed that the measured positions of the satellites have a moderate astrometric accuracy at
the level of 0.2-0.3 arcsec. Nevertheless, the comparison of the measured inter-satellite differences of
the major satellites of Saturn with theoretical ones points out that the errors of the mean values of (O-C)
are less than 0.1 arcsec (see Table 4).
Some of the observations of the Saturnian satellites Tethys, Dione, Rhea, Titan, and Iapetus obtained at
early epochs are worth the special attention to be digitized and re-processed with a high-accuracy astrometric catalogue, taking into account the small number of the observations of these satellites obtained
between 1945 and 1975.
References
1. G. Dourneau 1993. Orbital elements of the eight major satellites of Saturn determined from a fit of
their theories of motion to observations from 1886 to 1985. Astron. Astrophys. 267, 292-299.
2. J. D., Giorgini, D. K., Yeomans, A. B., Camberlin, P. W., Chadas, R. A., Jacobson, M. S., Keesey, J.
H., Lieske, S. J., Ostro, E. M., Standish, R. N., Wimberly 1996. JPL’s online Solar System data service.
Bull. Amer. Astron. Soc. 28, 1158.
3. D., Harper, D. B., Taylor 1993. The orbits of the major satellites of Saturn. Astron. Astrophys. 268,
326-349.
4. D., Harper, D. B., Taylor 1994. Analysis of ground-based observations of the satellites of Saturn
1874-1988. Astron. Astrophys. 284, 619-628.
157
5. E. M., Izhakevich, S. V., Kaltygina, S. P., Major, S. V. Shatokhina 1991. Position observations of
Jovian satellite VI at the Main Astronomical Observatory AS UkrSSR in 1987 - 1988. Kinematics Phys.
Celest. Bodies 7, p. 88 – 89 (In Russian).
6. E. M., Izhakevich, S. V., Kaltygina, I. V., Ledovskaya, S. V., Shatokhina 1994. Photographic position
observations of Jupiter’s external satellites in the years 1987-1989. Kinematics Phys. Celest. Bodies 10,
88-91 (in Russian).
7. E. M., Izhakevich, S. V., Shatokhina, V. V., Golovnya, I. V., Ledovskaya, S. P., Major 2001. Rereduction of the photographic observations of Mars and its satellites carried out from 1963 to 1988 at
the Main Astronomical Observatory of the Academy of Sciences of Ukraine using the PPM and ACT
catalogues. Kinematics Phys. Celest. Bodies 17, 65-70 (in Russian).
8. E. M., Sereda, E. M., Izhakevich 1978. Photographic positional observations of Mars and Deimos
with the 40-cm astrograph of the Main Astronomical Observatory of the Ukrainian Academy of Sciences
in 1973. Astrometriia i Astrofizika 36, 72-81 (In Russian).
9. S., Urban, T., Corbin, G., Wycoff 1997. The ACT reference catalogue. Bull. Amer. Astron. Soc. 29,
1306.
10. A., Vienne, L., Duriez 1995. TASS 1.6: Ephemerides of the major Saturnian satellites. Astron. Astrophys. 297, 588-605.
158