The OrbitTools Libraries
NORAD SGP4/SDP4 Implementations in C++ and C#
Michael F. Henry

Software Edition Information

The SGP4/SDP4 implementations are available in three editions: Public, Standard, and Professional.

The Public Edition is true to the original NORAD implementation.  It is available on this website for immediate download.  This version of the software is for non-commercial use only; commercial users must obtain either the Standard Edition or the Professional Edition.

The Standard Edition is identical to the Public Edition, except it also includes support for WGS-84 and the ECF coordinate system.  Intended for commercial use, a license fee is required (contact the author for more information).

The Professional Edition is similar to the Standard Edition, but also incorporates the changes recommended in "Revisiting Space Track Report #3".  This edition of the software provides the next level of accuracy and reliability for the most demanding tracking applications.  Intended for commercial use, a license fee is required (contact the author for more information.)  Professional Edition license holders may also purchase the optional Track Library

  Public Edition Standard Edition Professional Edition
License Fee Required No Yes Yes
Commercial Use Permitted No Yes Yes
Supports WGS-72 Yes Yes Yes
Supports WGS-84 No Yes Yes

Supports Earth Centered Fixed (ECF) coordinates

No Yes Yes

Optional Track Library Available

No No Yes
SGP4-2006 Compliant* No No Yes

*Implements "Revisiting Space Track Report #3" recommendations.

  Copyright  2009-2022 Michael F. Henry.
The author may be reached at