Databases (NSDC) of the Natural Planetary Satellites.
Principles and purpose of the project
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NSDC: Database of astrometric observations of Natural Planetary Satellites
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![[image]](img/tag5.jpg)
Why such a database?
The pecularity
of the dynamics of the natural satellites is such that for the determination of their
orbits and calculation of ephemerides all observations that have
been made after their discovery are necessary .
Separate researchers are occupied in improving the orbits of different
groups of satellites. They are thoroughly looking for observations in
different sources, creating their owndatabases which are then mostly inaccessible
to other researchers.
Creation of such database is a laborious process which includes manual entries
of data from publications, contacts with lots of observers, collecting data
files, unification of data formats, taking into account different non-standard
reductions. That is why there is a necessity for the creation of one unique database
of all observations of all planetary satellites.
Requirements for the database.
The database must have the following
properties: it should contain all satellite observations ever made in the world,
be accessible to any interested person, have standard and yet flexible format, and
expand constantly as new observations appear.
Entering and Formating Data.
Data were taken so that all numerical values
be transferred from publications or primary sources into the database without
any modifications, since all possible subsequent reductions of observations would
have been ambiguous because they depend on the current models of celestial
coordinates and time scales. On the other hand, it should be clear to the user of
the database which standards were applied by the observer when the results were
published. Such an approach lead to the fact that each set of observations
of planetary satellites that were entered into the database consists of two files.
The first file ("content") contains description of the observational results
(observed satellites, adopted coordinate system and time scale, observatory name
and code, telescope parameters, data format, etc.). The second file
("data") contains numerical values and is intended for reading by calculating
programs. The division of data into several sets is determined simply by the data
source and by the order in which they went into the database. In the file "content" with
explications, the reference is given to the data source as well as the
bibliographic reference. This reference is provided with a hyperlink which may be
used to call the corresponding reference from the bibliographic database.
From there, it is possible to pass this reference to the ADS Abstract Service
bibliographic database where the electronic version of the publication is
accessible.
Data sources.
Observations are taken from different sources,
from both printed publications (scientific journals) and electronic publications.
Some files are obtained directly from observers. A search for
observations was also made in difficult to access publications, for example in
Scientific papers deposited in ALL-RUSSIAN INSTITUTE OF SCIENTIFIC AND
TECHNICAL INFORMATION. Data are also taken regularly in electronic form from
the Minor Planet Electronic Circulars (MPEC). Some observations are received
as mails from the Minor Planet Center (MPC).
Current composition of the database NSDC.
By now our database contains about
90% of all observations of natural planetary satellites available worldwide. These
are 95,127 satellite positions divided into 231 sets.
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NSDC: Bibliographic database.
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![[image]](img/biblio.jpg)
Why a specific bibliographic database for Natural satellites?
Since there is enormous amount of publications,
the work with the bibliography becomes a very laborious process. So the optimal
choice of range of scientific field in which search is made becomes very
important. Creation of a well thought-out system of keywords can make search for
a pubication considerably easier.
Creation of the bibliographic database.
In 1996, decision has been taken in IMCCE to create the bibliographic database for
studies on natural planetary satellites. For this scientific field a special
system of keywords has been developed. Since that time, as a result of cooperation
between IMCCE and the Sternberg Astronomical Institute (SAI), the bibliography is
being constantly enriched. By now more than 3,000 references on theories of motion,
astrometry and observations and more than 6,000 references on physics of planetary
satellites have been collected.
Access facilities.
To provide easy access to the bibliographic database through Internet, a special program has
been elaborated in SAI. Formulation of inquiry is made using a large number of options.
Due to user-friendly interface of the program, user rapidly gets necessary
information. Output of unnecessary references is minimized.
Sources of the bibliographic data.
The main source of the
bibliographic database is the ADS Abstract Service. References from this database were
transformed to change their display. In addition, old keywords assigned by the
ADS Abstract Service were completely excluded and, according to the new system, new
keywords were assigned. When assigning the keywords, information is used
from the titles and abstracts of publications. We also have added considerable
bibliography of scientific papers published in less accessible journals such as
Scientific papers deposited in ALL-RUSSIAN INSTITUTE OF SCIENTIFIC AND
TECHNICAL INFORMATION and others.
More detailed information on the sources
of the bibliographic data is available (see "Sources").
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NSDC: Parameters - Data on the satellites
and their motion.
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![[image]](img/planet6.gif)
Usefulness of such information.
For all researches on the dynamics of the natural planetary satellites it is
necessary to have a system -- complete, well organized and easy accessible to any
user -- which includes numerous parameters describing physical properties and motion
of planets and satellites. Of particular importance is to have the newest data close
at hand. We provide such data and parameters for orbits, physics of the bodies
(masses, albedos, ...) rotation and poles. We provide also the code of algorithms allowing
to calculate the ephemerides.
Available information..
More detailed information on the sources is available in "Sources".
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| The future development of the service
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![[image]](img/fleur.jpg) Evolution of satellite orbits.
Origin of satellites.
Review of the most topical problems.
Studies in progress.
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