Home About PhotoGraphism PhotoExploration AstroEgypto Products Services Client Area Version française
About PhotoGraphism PhotoExploration AstroEgypto Products Services Client Area Legal Informations Version française

Source of orientation of a monument

Source of orientation of a monument

From the Vth millenium before our era dates the building of the very first megalithic monuments (menhirs, dolmens, cromlechs, ...). Most of these standing stones are characterized by a specific astronomical orientation : they were often built facing the rising or setting position of a bright celestial object (Sun, Moon, star, ...), indeed. It is the same for most of the later monuments dating from the mesopotamian, the egyptian, the mayan, the inca, ... periods.

This software leads to determine the astronomical source of orientation of any monument. It was conceived on the basis of the most recent algorithmic developments in astrometry and photometry. Since it takes into account the geographical (latitude, longitude and altitude of the site chosen for erection) and meteorological (temperature and relative humidity of the ambient air) conditions of observation, as well as the visual acuity of the stargazer, that is to say, our ability to distinguish a bright source in the background sky, this original software will give you results in quite good accordance with what was really observed at the epoch considered, that is to say, a list of stars visible with the naked eye whose sighting of the appearance or transit or disappearance position in the night or twilight sky explains at best the alignment of the monument considered. In some cases, the heliacal rising or setting of a star effectively was prefered to its rising or setting in the dark sky - mainly for worship reasons.

Orientation of a monument
ligne horizontale

This software invites you to determine the astronomical source of orientation of any monument erected between -4712 and 2025. Do do so, it uses data issued from the Hipparcos catalog (coordinates of 5043 stars visible with the naked eye), combines various astrometry (relative to the positioning of the stars in the sky) and photometry (relative to the brightness of the observed star and the conditions of local visibility) algorithms published within the scientific articles whose list appears below.

Free tests of this software are available within the Client Area. The access to the user interface of this software is made on payment : 45 euros, which can be paid via the Paypal secured paiement system (right button). This amount includes an unlimited access to the user interface and a free access to any future updates.

Price : 45,00 euros

ligne horizontale


Allen, C.W., "Astrophysical Quantities", Third Edition, Athlone, London, 1976.
Borkowski, K.M., "ELP 2000-85 and the Dynamical Time - Universal Time Relation", Astronomy and Astrophysics, 205 (1988), L8-L10.
Bower, F.A. et Ward, R.B., "Stratospheric Ozone and Man", CRC Press, Boca Raton, 1982
Bureau des Longitudes, "Introduction aux Ephémérides Astronomiques", EDP Sciences 1998.
Centre de Données Astronomiques de Strasbourg : http://cdsweb.u-strasbg.fr .
Chapront-Touzé, Michelle et Chapront, Jean, "Lunar Tables and Programs from 4000 BC to AD 8000", Willmann-Bell, Richmond, 1991, pp 6-7.
Garstang, R.H., "Night-Sky Brightness at Observatories and Sites", PASP101, 306-329, 1989.
Hayes, D.S., et Latham, D.W., "Rediscussion of the Atmospheric Extinction and the Absolute Spectral-Energy Distribution of Vega", Astrophysic Journal, 197, 593-601, 1975.
Hecht, S., "Visual thresholds of steady point sources of light in fields of brightness from dark to daylight", Journal of the Optical Society of America, 37, 59, 1947.
JPL Horizons : http://ssd.jpl.nasa.gov/horizons.html.
Koomen, M.J., Lock, C., Parker, D.M. , Scolnik, R., Tousey, R. et Hulburt, E.O., "Measurements of the Brightness of the Twilight Sky ", Journal of the Optical Society of America, 42, 353-356, 1952.
Krisciunas, K et al., "Atmospheric Extinction and Night-Sky Brightness at Maunea Kea", PASP 99, 887-894, 1987.
Krisciunas, K., "Further Measurements of Extinction and Sky Brightness on the Island of Hawaï", PASP 102, 1052-1063, 1990.
Krisciunas, K. et Schaefer, B. E., "A Model of the Brightness of Moonlight", PASP, 103, 1033-1039, 1991.
Meinel, A. et Meinel, M., "Sunsets, Twilights and Evening Skies", Cambridge University Press, Cambridge, 1983.
Pilachowski, C.A., Africano, J.L., Goodrich, B.D. et Binkert, W.S., "Sky Brightness at the Kitt Peak National Observatory", PASP 101, 707-712, 1989.
Pyaskovskaya-Fesenkova, E.V., "Investigations of the scattering of light in the earth's atmosphere", USSR Academy, Science Press, Moscow, 1957.
Rozenberg, G.V., "Twilight", Plenum, New York, 1986
Saemundson, T., "Atmospheric Refraction", Sky & Telescope, 72, 70, 1986.
Schaefer, Bradley E., "Atmospheric Extinction Effects on Stellar Alignments", Archaeoastronomy n°10 (JHA, xvii (1986)).
Schaefer, Bradley E., "Telescopic Limiting Magnitudes", PASP 102, 212-229, 1990
Schaefer, Bradley E., "Astronomy and the limits of vision", Vistas in Astronomy, Volume 36, pp 311-361, 1993.
Schaefer, Bradley E., "The latitude of the observer of the Almagest star catalogue", JHA xxxii, 2001.
Simon, J.L., Bretagnon, P., Chapront, J., Chapront-Touzé, M., Francou, G., Laskar, J., "Numerical expressions for precession formulae and mean elements for the Moon and the planets", Astronomy Astrophysics 282, 663-683 (1994).
Stephenson, F.R., "Historical Eclipses and Earth Rotation", Cambridge University Press, Cambridge, 1997.
Stephenson, F.R. et Morrison, L.V., "Long-Term Fluctuations in the Earth's Rotation : 700 BC to AD 1990", Philosophical Transactions of the Royal Society of London, Ser. A, 351 (1995), 165-202.
Stephenson, F.R. et Morrison, L.V., "Long-Term Changes in the Rotation of the Earth : 700 BC to AD 1980", Philosophical Transactions of the Royal Society of London, Ser. A, 313 (1984), 47-70.
Tousey, R. et Hulburt, E.O., "Visibility of Stars in the Daylight Sky", Journal of the Optical Society of America, 38, 886-896, 1948.
Weaver, H.F., "Visibility of Stars Without Optical Aid", PASP 59, 232-243, 1947.

ligne horizontale

Important Note: The Culture Diff' company undertakes to ensure that the collection and processing of your personal data, carried out via the www.culturediff.org portal, comply with the General Data Protection Regulations (RGPD) established on 25 May 2018 and the Data Protection Act of 6 January 1978. When transmitted to the Culture Diff' company, your personal data (first name, last name, postal and electronic addresses) therefore remain absolutely confidential. In addition, the Culture Diff' company has joined the PayPal payment system, so that your payments by credit card or PayPal account benefit from the highest security.

PayPal Logo