MacTutor
We have lost in M. Bigourdan a veteran astronomer who for many years, at the Paris Observatory, worked with the utmost assiduity in the observations of the positions of nebulae and clusters, and was later Director of the Bureau International de l'Heure from its commencement until 1928.
Born at Sistels (Tarn-et-Garonne) on April 6, 1851, he graduated from the École d'Astronomie in Paris and in 1877 was appointed by Tisserand as an assistant in the Observatory of Toulouse. He was put in charge of the meridian instrument, but held this post for only a short time, as Tisserand was appointed Director of the Paris Observatory shortly afterwards and brought Bigourdan to Paris in 1879, where he was given charge of the great equatorial. He at once commenced the great work of determining by visual observations the accurate positions of all the known nebulae of the northern hemisphere. He never missed a fine night, and his observations are published in five volumes of the Annales of the Paris Observatory and occupy no less than three thousand pages. He gives a history of the discovery and previous observations of these nebulae. The intention underlying these arduous observations was that the positions of these distant objects might be sufficiently well known for astronomers in the future to determine their motions. Incidentally, he discovered many new nebulae and made measures of the positions of comets and double stars.
In 1882 M. Bigourdan took part in the observations of the transit of Venus in Martinique. Benefiting from his stay on the island, he made observations of the comet of that year, for which he was awarded the Lalande Prize. In 1892 he went to Senegal to observe the total eclipse of the Sun, and on the same expedition made a determination of the value of gravity at Joal. In 1900 and 1905 he observed total eclipses of the Sun in Spain and Tunis.
Owing to discordances in the previous determinations of the longitude Paris-Greenwich, a redetermination was made in 1902. The French observers, M. Bigourdan and M. Lancelin, worked in parallel with the English observers, F. W. Dyson and H. P. Hollis. The previous discrepancy was cleared up and results obtained in satisfactory agreement, the concluded value differing only 08-01 from the recent determinations, which had the advantage of a moving micrometer and wireless time signals.
M. Bigourdan was interested in the transmission of time signals by wireless, due largely to the initiative of General Ferrié. On his suggestion, the installation at Greenwich was erected in 1912, and the signals from the Eiffel Tower were recorded daily. After the conferences in Paris in 1912 and 1913, the International Time Service was established, with a Bureau in Paris, of which M. Bigourdan was constituted Director. The War intervened, but after its conclusion, M. Bigourdan remained Director in close touch with M. Baillaud and General Ferrié.
M. Bigourdan was made a member of the Bureau de Longitudes in 1903 and continually enriched the Annuaire with notices on interesting research in current astronomy, such as determinations of parallax, classification of stellar spectra, and variable stars After his retirement from the Bureau de l'Heure in 1928, when he was seventy-seven years old, he gave a history of the Bureau de Longitudes in the Annuaire. The fourth part of this history was published in 1932, only a short time before his death. His most important historical work, Annales célestes du dix-septième siècle, by A. G. Pingré, has a curious history. The manuscript was completed in 1791, and a beginning made of its publication. This went on, very slowly until the death of Pingré and then ceased. The manuscript was lost and found by M. Bigourdan at the Paris Observatory under a wrong designation. It was printed in 1901 under the auspices of the French Academy.
M. Bigourdan was elected a member of the Académie des Sciences in 1904 and became Vice-President in 1923. He attended many astronomical conferences, both in Paris and other cities, where he put forward his views with vigour and courtesy.
He married a daughter of Admiral Mouchez, the Director of the Paris Observatory, who inaugurated the Carte du Ciel.
M. Bigourdan was elected an Associate of the Royal Astronomical Society on November 13, 1903, and was awarded the Gold Medal in 1919.
F. W. D
Born at Sistels (Tarn-et-Garonne) on April 6, 1851, he graduated from the École d'Astronomie in Paris and in 1877 was appointed by Tisserand as an assistant in the Observatory of Toulouse. He was put in charge of the meridian instrument, but held this post for only a short time, as Tisserand was appointed Director of the Paris Observatory shortly afterwards and brought Bigourdan to Paris in 1879, where he was given charge of the great equatorial. He at once commenced the great work of determining by visual observations the accurate positions of all the known nebulae of the northern hemisphere. He never missed a fine night, and his observations are published in five volumes of the Annales of the Paris Observatory and occupy no less than three thousand pages. He gives a history of the discovery and previous observations of these nebulae. The intention underlying these arduous observations was that the positions of these distant objects might be sufficiently well known for astronomers in the future to determine their motions. Incidentally, he discovered many new nebulae and made measures of the positions of comets and double stars.
In 1882 M. Bigourdan took part in the observations of the transit of Venus in Martinique. Benefiting from his stay on the island, he made observations of the comet of that year, for which he was awarded the Lalande Prize. In 1892 he went to Senegal to observe the total eclipse of the Sun, and on the same expedition made a determination of the value of gravity at Joal. In 1900 and 1905 he observed total eclipses of the Sun in Spain and Tunis.
Owing to discordances in the previous determinations of the longitude Paris-Greenwich, a redetermination was made in 1902. The French observers, M. Bigourdan and M. Lancelin, worked in parallel with the English observers, F. W. Dyson and H. P. Hollis. The previous discrepancy was cleared up and results obtained in satisfactory agreement, the concluded value differing only 08-01 from the recent determinations, which had the advantage of a moving micrometer and wireless time signals.
M. Bigourdan was interested in the transmission of time signals by wireless, due largely to the initiative of General Ferrié. On his suggestion, the installation at Greenwich was erected in 1912, and the signals from the Eiffel Tower were recorded daily. After the conferences in Paris in 1912 and 1913, the International Time Service was established, with a Bureau in Paris, of which M. Bigourdan was constituted Director. The War intervened, but after its conclusion, M. Bigourdan remained Director in close touch with M. Baillaud and General Ferrié.
M. Bigourdan was made a member of the Bureau de Longitudes in 1903 and continually enriched the Annuaire with notices on interesting research in current astronomy, such as determinations of parallax, classification of stellar spectra, and variable stars After his retirement from the Bureau de l'Heure in 1928, when he was seventy-seven years old, he gave a history of the Bureau de Longitudes in the Annuaire. The fourth part of this history was published in 1932, only a short time before his death. His most important historical work, Annales célestes du dix-septième siècle, by A. G. Pingré, has a curious history. The manuscript was completed in 1791, and a beginning made of its publication. This went on, very slowly until the death of Pingré and then ceased. The manuscript was lost and found by M. Bigourdan at the Paris Observatory under a wrong designation. It was printed in 1901 under the auspices of the French Academy.
M. Bigourdan was elected a member of the Académie des Sciences in 1904 and became Vice-President in 1923. He attended many astronomical conferences, both in Paris and other cities, where he put forward his views with vigour and courtesy.
He married a daughter of Admiral Mouchez, the Director of the Paris Observatory, who inaugurated the Carte du Ciel.
M. Bigourdan was elected an Associate of the Royal Astronomical Society on November 13, 1903, and was awarded the Gold Medal in 1919.
F. W. D
Friedrich Wilhelm Bessel's obituary appeared in Monthly Notices of the Royal Astronomical Society 93:4 (1933), 233-234.