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Build Status GoDoc Go Walker

Selected algorithms from the book "Astronomical Algorithms" by Jean Meeus, following the second edition, copyright 1998, with corrections as of August 10, 2009.

Repository organization

The branch "master" has the current version. Tags exist with "semantic versions" with a three-part major.minor.fix format like v3.0.0. Older versions can be checked out by tag. Also a branch or branches should exist for older versions.

Beginning with v3.0.0, code will be organized as a vgo "module" in a subdirectory, named like v3 corresponding to the current major version.

Package organization

Package meeus is a documentation-only package. Algorithms are implemented in subdirectories under meeus, one for each chapter of the book. In addition there is a package "base" with additional functions that may not be described in the book but are useful with multiple other packages.

See meeus package documentation for a chapter title cross-reference.



Routines of the planetposition package require "VSOP87" data files. These files should be available from public sources, for example VisieR. The files needed by planetposition are the VSOP87 "B" files. It is sufficient to download the eight files

VSOP87B.ear  VSOP87B.mar  VSOP87B.nep  VSOP87B.ura
VSOP87B.jup  VSOP87B.mer  VSOP87B.sat  VSOP87B.ven

There are no requirements on where you place these files in your file system but you may find it convenient to create a directory for them and set an environment variable VSOP87 to this directory.

Install package software with go get

Technically, go get is sufficient.

The tests also require the sexagesimal package, so use the -t option to prompt go get to find it as a test dependency:

go get -t


With all eight VSOP87 files dowloaded as described above, and with an environment variable set to their location, then from the meeus directory

go test ./...

works as usual to run all tests in all subdirectories of meeus.

To run all tests except for those requiring planet positions computed from the VSOP87 files, use

go test -tags nopp ./...

("nopp" for no planet positions)


Experimentally, you can try vgo.

To run package tests, clone the repository -- anywhere! it doesn't have to be under GOPATH -- and from the cloned directory run

vgo test all

Vgo will fetch the sexagesimal test dependency as needed and run all package tests.

Copyright and license

All software in this repository is copyright Sonia Keys and licensed with the MIT license.


Implementation of "Astronomical Algorithms" by Jean Meeus




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