petersburg on pulkovo mountain; from that moment to this day , the pulkovo observatory remains the mainbservatory of the russian academy of sciences. it was built in 4 years. the first seven employees determined the positions of the stars and compiled catalogs of the starry sky. geographical studies of the territory of russia were carried out. the observatory was also used to develop facilities navigation. since 1844, the pulkovo meridian, passing through the center of the main building of the observatory, began to be used as a reporting point for geographic longitude in russia. for 40 years, all ships of the empire reported their longitude from it, until the countries accepted it as a single reference point on the planet greenwich. in 1920 , the observatory began transmitting precise time radio signals during the great patriotic war; it was completely destroyed, but then it was restored. now the work of the pulkovo observatory is complicated by the fact that the territory in its security zone is being actively developed. 3 july 1962 france officially recognized algerian independence. f