The software package ERA (Ephemerides for Research in Astronomy) is a problem-oriented software system for solving heterogeneous calculating tasks of Ephemeris and Dynamical Astronomy. The package makes it possible to produce ephemeris calculations needed for both planning various observational programs and processing the resulting observations.
The package may calculate ephemeris predictions for position observations of any type: classical photographic or meridian positions of any Solar System objects on the Celestial Sphere, astronomical events (such as solar or lunar eclipses, as well as the events in satellite systems), modern high-tech observations (ranging to planets, to the Moon or spacecraft, VLBI, pulsar timing, doppler shifts or one-way pseudo-distances). The observed objects may be galactic or extragalactic bodies as well as the Solar System bodies: the major planets, the Moon, natural satellites of the major planets, minor planets and comets, spacecraft, landers, artificial satellites.
In addition to standard dynamical models embedded into the ERA (the lunar-planetary ephemerides of JPL — DE403/LE403, DE405/LE405, DE406/LE406, DE421, DE423, DE430, DE432, the IMCCE ephemerides — INPOP06, INPOP08, INPOP10a, INPOP13C, and the EPM ephemerides developed in IAA RAS— EPM2004, EPM2008, EPM2011, EPM2013), user-made numerical dynamical models may be constructed which are adequate in accuracy to the contemporary observations. Parameters of these models may be improved from the analysis of corresponding observations using tools provided by the ERA. The system includes packages of processing the position observations by both the Least Squares Method and by Kalman filtering.
The package ERA is based on the specialized high-level language SLON which uses vocabulary similar to the standard astronomical terminology. After describing an astronomical task in terms of the language SLON, a translator is called out. The translated program automatically calls out all the necessary subroutines from the embedded applied program package. As a result, the predicted ephemeris values of the observed parameters are calculated and, if necessary, compared with their observed counterparts estimating parameters of the mathematical model.
The language SLON is of a relational type and includes an astronomically oriented data-base managing system. In this way, the problem of keeping and saving astronomical data as well as the problem of their modeling is solved in the framework of the same astronomical software package.
At present, the package ERA is the main universal tool for calculating the ephemeris data published in both Russian Astronomical Yearbook and the specialized Naval Astronomical Yearbook. In routine work, the thoroughly tested DOS-version of the ERA is still used, as well as its 32-bit platform-independent Windows/Linux beta-version.
The long -term practical work with ERA package for processing various observation programs has proved high efficiency of the ideas realized in the package.