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Credits

The Great Circle Mapper, including all software, data, and the compilation and presentation of the data is Copyright © 1996-2014 Karl L. Swartz. All rights reserved.

The Great Circle Mapper name and logo are trademarks of the Great Circle Mapper.

Additional credits, copyrights, and licenses apply as detailed below.

Software

Great Circle Mapper software incorporates several third-party software libraries:

Geodesic calculations use custom software based on formulae developed by Thaddeus Vincenty, with modifications by Charles Karney based on work by Friedrich Bessel to improve performance and accuracy. (See How does the Great Circle Mapper calculate distances and paths? in the FAQ for additional information and references.)

Primary development of the Great Circle Mapper is done using an Apple Macintosh and servers running FreeBSD. The site is hosted using the Apache HTTP Server running on FreeBSD.

Made on a Mac

Mac and the Mac logo are trademarks of Apple Computer, Inc., registered in the U.S. and other countries. The Made on a Mac Badge is a trademark of Apple Computer, Inc., used with permission.

Map Data

The Great Circle Mapper uses pre-rendered maps, stored in a custom, high-performance image format. These maps are built offline from multiple sources:

Airport Data

The Great Circle Mapper's location database includes information about landing facilities (including airports) and other types of locations compiled from many sources including those listed below. Specific source credits are noted on the information page for the airport or location.

Other Data

Magnetic variation information is derived from the World Magnetic Model (WMM), a product of the U.S. National Geospatial-Intelligence Agency (NGA) and the U.K. Defence Geographic Centre (DGC) which was developed jointly by the U.S. National Geophysical Data Center (NGDC) and the British Geological Survey (BGS). This data is in the public-domain and is not subject to copyright protection.

Time zone definitions including daylight saving time (DST) transitions use the public-domain Timz Zone Database (aka tz or zoneinfo). The time zone for a given location is derived from official airport data or other sources and may not be correct.

Weather data (METAR and TAF) is from the NOAA Internet Weather Source.

Flags

Flags used on the airport information pages are from one or more of the following vexillological sources:

 

Copyright © 1996-2014 Karl L. Swartz. All rights reserved.
The Great Circle Mapper name and logo are trademarks of the Great Circle Mapper.
All other trademarks mentioned herein belong to their respective owners.
Please see credits for attibutions and further copyright information.

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