Credits

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

Software

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

Portions of this software are copyright © 2009 The FreeType Project and are used under license.
GIF image processing is loosely derived from parts of Netpbm (license and copyright terms).
AES encryption is implemented using software from Brian Gladman (license and copyright terms).
SHA-1 signatures are implemented using software derived from RFC 3174 (license and copyright terms).

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.

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 image format. These maps are derived offline from multiple sources:

Plain maps and political boundaries are derived from GMT (Generic Mapping Tools). (No GMT code is used in the online portion of the web site.)
Blue Marble maps are based on Blue Marble: Next Generation (and Blue Marble) imagery from NASA's Earth Observatory.
Lunar maps use public domain imagery, based on data from the Clementine mission processed into images by the United States Naval Research Laboratory. Some Clementine imagery was obtained via Calvin J. Hamilton's Views of the Solar System.

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.

The primary source for most landing facilities in the United States is the FAA, provided by Paulo Santos (AirNav).
The primary source for most landing facilities in Iceland is the Icelandic Civil Aviation Administration, provided by Sigurbjörn Ragnarsson (Flugnet) with translation help where needed.
The primary source for landing facilities in many other countries is the Aeronautical Information Publication (AIP) of the civil aviation adminstration which regulates the facility.
The primary or secondary source for numerous landing facilities is the last public release (cycle 0610, effective 28 September 2006 to 25 October 2006) of DAFIF^®, a product of the National Geospatial-Intelligence Agency. The Great Circle Mapper has not been endorsed or otherwise approved by the National Geospatial-Intelligence Agency, the former National Imagery and Mapping Agency, or the United States Department of Defense (10 U.S.C. § 425).
Some airport information has been derived from the Bones Aviation Page with the permission of John Woodside.
Photogrammetry by the Great Circle Mapper is used for some airports where official sources are unavailable. The processes used have been verified using airports for which accurate, reliable information is available.
Additional airport information has been contributed by Thomas Jäger, Iikka Meriläinen, Yann Gascard (Virtual Pilots Association), Nils Rennenberg, and many others.

Other Data

Time zone definitions including daylight saving time (DST) transitions use the public-domain tz database. 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:

Mooney's MiniFlags, with the kind permission of Edward Mooney, Jr.
The CIA's Flags of the World (part of the World Factbook).
Roberto Breschi's Bandiere, used with permission.
Flags from Australia at OzOutback, used with permission.
flags-and-anthems.com.
Various government and public domain sources.