Almanac

Sources & licences

Almanac – Ancient Cycles

Every date and alignment in Almanac is calculated on your iPhone from published astronomy and archaeology. This page lists those sources, as the app does under Personalize → Sources & licences, and reproduces the one open-source licence the app must carry.

Astronomy

Ancient sites

Each alignment’s bearing and dates come from the surveys below. In the app, tap “Show the math” on any alignment to see its bearing, horizon height, tolerance and source. Several readings are contested, and the app says so where they are. Where no surveyed bearing has been published, the bearing is calculated and marked as low confidence.

Stonehenge

Ruggles 1997, Proceedings of the British Academy 92, Table 7.

Newgrange

Patrick 1974, Nature 249; Ray 1989, Nature 337.

Maeshowe

Historic Environment Scotland (dates); Reijs, archaeocosmology.org (light window).

Callanish

Higginbottom & Clay 2016, Journal of Archaeological Science: Reports.

Chimney Rock

Malville, Eddy & Ambruster 1991, Archaeoastronomy 16.

Chichén Itzá

Šprajc & Sánchez Nava 2013, Estudios de Cultura Maya 41.

Teotihuacan

Šprajc 2000, Latin American Antiquity 11(4); Dow 1967; Aveni 2001, Skywatchers.

Uaxactún, Group E

Šprajc 2021, PLOS ONE 16(4).

Abu Simbel

Shaltout & Belmonte 2005, Journal for the History of Astronomy 36; Weyburne 2021, ENiM 14.

Karnak

Shaltout & Belmonte 2005, Journal for the History of Astronomy 36.

Angkor Wat

Magli 2016, arXiv:1604.05674.

Machu Picchu

Kościuk & Ziółkowski 2020, Teka 16(4); Dearborn & White 1983, Archaeoastronomy 5.

Göbekli Tepe

Magli 2016, Nexus Network Journal 18; Dietrich et al. 2013 (dates).

Warren Field

Gaffney et al. 2013, Internet Archaeology 34.

Goseck Circle

Schlosser, in Bertemes et al. 2004.

Giza

Spence 2000, Nature 408; Rawlins & Pickering 2001, Nature 412; Nell & Ruggles 2014; Petrie; Dash; Badawy & Trimble 1964; Bauval 1993; Gantenbrink (shaft angles); Lehner 1985.

Calendars

Illustrations

The calendar glyphs, wheels, site drawings and moon phases are schematic teaching illustrations made for Almanac. They are not epigraphic or survey records.

ERFA licence

Almanac’s long-term precession is ported from ERFA (eraLtp, eraLtpecl, eraLtpequ), which is distributed under the licence below.

Copyright (C) 2013-2023, NumFOCUS Foundation.
All rights reserved.

This library is derived, with permission, from the International
Astronomical Union's "Standards of Fundamental Astronomy" library,
available from http://www.iausofa.org.

The ERFA version is intended to retain identical functionality to
the SOFA library, but made distinct through different function and
file names, as set out in the SOFA license conditions.  The SOFA
original has a role as a reference standard for the IAU and IERS,
and consequently redistribution is permitted only in its unaltered
state.  The ERFA version is not subject to this restriction and
therefore can be included in distributions which do not support the
concept of "read only" software.

Although the intent is to replicate the SOFA API (other than
replacement of prefix names) and results (with the exception of
bugs;  any that are discovered will be fixed), SOFA is not
responsible for any errors found in this version of the library.

If you wish to acknowledge the SOFA heritage, please acknowledge
that you are using a library derived from SOFA, rather than SOFA
itself.


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