Bulletin Horaire

Bureau International de l'Heure

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Bulletin Horaire was the regular publication in which the Bureau International de l'Heure (BIH) presented the results of their work intercomparing time services around the world. Initially the circulars of Bulletin Horaire were published every other month in a sequence of Tomes (Volumes). The dates on the title page of the circulars were the day they were submitted for typesetting. The content of each circular was as much of the data as had been possible to gather and reduce as of its bi-monthly date. This initial sequence of tomes (volumes) was numbered 1 through 7, and those covered the years from 1921 through 1941. For circulars of Bulletin Horaire during this initial period of the tomes (volumes) the date ranges of the tables of data are always some months behind the date on the title page.

The BIH was located at Observatoire de Paris, and the events of World War 2 drastically altered the operations of BIH. Foreign postal service did not happen during the German occupation of Paris from 1940-06-14 to 1944-08-25. Nevertheless, the staff of the BIH maintained all of their local scientific activity despite the conditions in Paris. The calculation of Heure demi-définitive depended only on activity at Observatoire de Paris, and that activity continued without interruption. The calculation of Heure définitive required postal service from distant observatories to report their receptions of radio broadcast time signals. Thus it was not possible to determine values of Heure définitive during the war.

The pattern of numbered collections of circulars continued in subsequent publications of Bulletin Horaire. The circulars with tables of Heure demi-définitive were issued in Series 3, 4, 5, and 6 through the year 1964, and these were individually numbered. In addition to the tables of Heure demi-définitive and other timely articles these circulars also contained the Annual Reports of the BIH.

The pattern of lettered collections of circulars continued in subsequent publications of Bulletin Horaire. The circulars with tables of Heure définitive were issued in Series E, F, G, and H through the year 1963. The circulars with Heure définitive in the lettered series generally appeared about 8 months later than the corresponding circulars with Heure demi-définitive in the numbered series.

Nicolas Stoyko had worked at BIH since 1924, and he was in charge of BIH in the early 1960s. His wife Anna Stoyko had worked at BIH since 1947. They both retired in 1965 March just after the BIH had defined coordinated Universal Time as a function of the atomic time scale being maintained at BIH. The next series of issues of Bulletin Horaire completely changed its format and was called "Series J" Initially the circulars of Bulletin Horare in Series J continued providing both Heure demi-définitive and Heure définitive as had been done since the era of pendulum clocks and time signals transmitted over radio along with Morse code. Soon Series J changed its format to provide tables of time service comparisons consistent with space-age telecommunications and atomic chronometers.

BIH Bulletin Horaire ended with series J.
After that BIH produced the monthly Circular D with rapid results and BIH Annual Report with full review of the data. These continued through 1987 until the BIH was dismantled with its earth rotation aspects going into the new IERS and its precision timekeeping aspects going to the BIPM.