PhD thesis

Fourteen years. Such was the time needed to turn a simple idea
- to study, by means of appropriate methods, the sky of ancient Egypt -
into a full thesis subject, of which the examination of the manuscript and the defense
brought together for the first and only time renowned Egyptologists and Astronomers.
It was on May 21, 2008. On that very day, Toulouse was the capital of interdisciplinarity.

Introduction

It was at the Laboratoire d'Astrophysique de Toulouse-Tarbes, a former joint research unit of the University of Toulouse and the CNRS (UMR 5572), that I prepared my doctoral thesis on ancient Egyptian astronomy (2002-2008), under the supervision of Robert Nadal, an astronomer specializing in ancient Greece, and then Sylvie Roques, CNRS Research Director. In 2011, this research laboratory of the Observatoire Midi-Pyrénées became the Institut de Recherche en Astrophysique et Planétologie (IRAP, UMR 5277).

Thesis title : « Design of a naked-eye star visibility model. Application to the identification of Egyptian decans »

Summary : On the inside lids of sarcophagi, on the outer surfaces of clepsydras, on the ceilings of temples and tombs dating from 2100 to 50 BC and located along the Nile Valley between Alexandria and Aswan, are inscribed twenty stellar clocks and eighty star lists in the order of their heliacal risings, of their nocturnal risings or culminations in the local meridian. Because their heliacal risings took place ten days apart, these stars were qualified as decanal. Their identification with stars visible to the naked eye (of apparent magnitude less than or equal to 6) in the Hipparcos catalog required :

1. the creation of an archaeological database based on the one hundred remains (star clocks and star lists) discovered to date ;
2. the creation of a catalog of the 90 Egyptian decans, accompanied by the meaning of their respective hieroglyphic appellations ;

3. the examination of the stellar arrangements characterizing each of the hundred vestiges in order to determine the time conditions (when the lists of decanal stars were compiled) and the spatial conditions (latitude of the site where the decanal stars were observed) for observing the decanal stars in the ancient Egyptian sky ;
4. the study of various writings mentioning the heliacal rising of the star Sirius in Egypt's past (Papyrus el-Lahoun, Ebers Calendar, Foundation Text of the Temple of Hathor at Denderah, etc.) in order to determine the visual conditions for observing the decans in the ancient Egyptian sky ;

5. the conception of a model for the visibility of stars to the naked eye in the twilight sky and the night sky of ancient Egypt. This model combines various astrometric parameters (proper motion of the stars, precession of the world axis, etc.) and various criteria for the visibility of an object in the sky (increase in apparent magnitude due to atmospheric extinction, brightness of the sky in place of the object in question, visual acuity of the observer). ;
6. the examination of the succession of star apparitions and culminations under the given temporal, spatial and optical conditions, in relation to the hundred lists available to us ;
7. the application of various astronomical criteria (apparent magnitude, color index, time of rising or culmination of each star) and egyptological criteria (meaning of the hieroglyphic name of each decan and associated celestial imagery) to each of the samples of candidate stars for the Egyptian decans provided by the model ;
8. testing the strength of the proposed identifications against realistic variations in historical period, latitude of the observation site, local weather conditions and the observer's visual acuity.

The scientific contributions of this thesis: This work has enabled the cartography of the southern sky of ancient Egypt to be drawn up. It has also made it possible to refine the dates of the beginning of the reigns of several pharaohs (Sesostris III, Amenhotep I and Thutmosis III), to better understand the division of (nocturnal) time into hours, etc.

Thesis defense

I defended my thesis on May 21, 2008 at the Laboratoire d'Astrophysique de Toulouse-Tarbes before a jury of six astronomer-physicists and an Egyptologist:

Georges Balmino, CNES Engineer Emeritus, Earth and Planetary Dynamics Laboratory, Midi-Pyrénées Observatory ;
Alain Blanchard, Professor of Physics at Toulouse Paul Sabatier University ;
Nicole Capitaine, Astronomer at Paris Observatory ;
Leo Depuydt, Professor of Egyptology at Brown University ;
Daniel Egret, President of Paris Observatory ;
Sylvie Roques, CNRS Research Director, Toulouse-Tarbes Astrophysics Laboratory, Midi-Pyrénées Observatory ;
David Valls-Gabaud, CNRS Research Fellow, GEPI, Meudon Observatory

My thesis defense resulted in the award of the title of Doctor of Astronomy from the University of Toulouse, with the highest distinction.

Documents available for download

Twelve scientific articles have been written as a result of this thesis, and are available for download in the ArchaeoAstronomy > Publications section.
The slideshow of my doctoral thesis defense is available for download here (in French only).
The manuscript of my doctoral thesis is available for download on the TEL multidisciplinary thesis server.

Innovative archaeoastronomy softwares

This thesis work required the design of three software programs:

a software to determine the heliacal rising and setting dates of any star visible to the naked eye,
a software to calculate the times at which the spring and autumn equinoxes and the summer and winter solstices occur,
a software to determine the astronomical source of orientation of any monument erected since the year 4713 BC.

Log on to the Client Area and try out each of these software packages for free! Proceed to purchase and get lifetime access to their complete and regularly updated user interface.

Prize from the Académie des Sciences, Inscriptions et Belles-Lettres de Toulouse

On December 7, 2008, 24 “young” PhD graduates received a prize from the Académie des Sciences, Inscriptions et Belles-Lettres de Toulouse at the Hôtel d'Assezat. Here is the text of the speech by the President of the Academy: « The Academy's prize crowns the work of Mademoiselle Karine Gadré, nominated by Mr. Roger Bouigue, Honorary Director of the Astronomical Observatory and University Professor. Mademoiselle Gadré's work is entitled “La conception d'un modèle de visibilité d'étoile à l'oeil nu. Application à l'identification des décans égyptiens”. The author of this thesis uses our current knowledge of Astronomy to “sort” the stars used by the Egyptians and draw up a set of tables analogous to those appearing in hieroglyphic form, tables constituting veritable “stellar clocks”. From a scientific point of view, Mademoiselle Gadré's work provides a sound basis for the training of future researchers in archaeoastronomy, and encourages the development of closer collaboration between Egyptologists and Astronomers. »

Prize awarded by the Académie des Sciences, Inscriptions et Belles-Lettres de Toulouse

A medal bearing the effigy of Pierre de Fermat and engraved with the name of each prizewinner accompanies the certificate of the Prize awarded by the Académie des Sciences, Inscriptions et Belles-Lettres de Toulouse.