Institute of Applied Astronomy of Russian Academy of Sciences, 8 Zhdanov st., St. Petersburg, 197042 Russia
ERA is an integrated programming system designed for processing position observations of high accuracy in astronomy, astrodynamics and space geodesy. It supports ephemerides practically for any objects of Solar system: major and minor planets, comets and space probes, landers or crates on planet surfaces, satellites of outer planets and Earth artificial satellites.
With the help of the system any types of observables may be modelled: absolute or differential positions on the celestial sphere (including various types of events) as well as observations of modern techniques (range and doppler, pseudorange and pulsar timing, VLBI observables).
The core of the system is a translator from a problem oriented programming language SLON in which the user has to describe the astronomical data to be processed. By this way the user interacts implicitly with a build-in applied program package for ephemeris and dynamic astronomy. Being of a relation type, the language includes a data managing system to handle data presented in the form of tables ("relations").
The system makes it possible to construct a user's own dynamic theory by a method of numerical integration for any celestial body mentioned above and evaluate parameters of the theories by comparing ephemeris predictions with appropriate observations. Partials with respect to the estimated parameters may be computed for any type of observables by integrating variation equations; then the residuals may be processed by a build-in package of the least square method.
The system was thoroghly tested by processing a large set of various observation program. Many of the testing programs are included to a context-sensitive helper and may be run while learning the system.