# VSOP87 Functions used to Compute Planetary Positions (1.15 MB)

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Jay_Tanner**Version Compatibility:*** Visual Basic 5 *

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These functions are a VB version of the complete VSOP87 planetary theory designed to be used to in a program to compute the heliocentric ecliptic longitude, latitude and distance of the planets Mercury to Neptune over a period of several thousands of years to about 1 arcsecond of precision. They are intended for use by programmers desiring to make their own astronomical computations programs. These heliocentric computations are the first important step in that direction. They are not for the mathematically squeamish. These functions are NOT the amateur formulas seen in many popular astronomical computing books. They are the FULL VSOP87 series, some of which consist of well over 1100 terms. The series of terms may be truncated depending on the precision you require for your own computations.

The modules perform the bulk of the arduous mathematics saving the programer much tedious and error prone labor involved with transcribing data from books into a program.

To anyone familiar with books such as "Astronomical Algorithms" by Jean Meeus, these programs perform the familiar tasks of computing the heliocentric, ecliptical longitude L, latitude B and radius vector R (distance to the sun) for a planet at any given instant T.

These functions assume the user has a sufficient working knowledge of the advanced math required to apply them to their purpose.

Other essential info is included in the zipped archive of the function files in HTML format.

**Instructions:**Click the link below to download the code. Select 'Save' from the IE popup dialog. Once downloaded, open the .zip file from your local drive using WinZip or a comparable program to view the contents.

Download vsop87functions.zip