The son of Michael Kirch, a shoemaker in Guben, Electorate of Saxony, initially he worked as a schoolmaster in Langgrün and Neundorf near Lobenstein. He also worked as a calendar-maker in Saxonia and Franconia. He began to learn astronomy with Erhard Weigel in Jena, and with Hevelius in Danzig. In Danzig in 1667, Kirch published calendars and built several telescopes and instruments. In 1679 he invented a screw micrometer for astronomical measurements. He became an astronomer working in Coburg, Leipzig and Guben as well from 1700 in Berlin. In the last quarter of the 17th century, Kirch was the most-read calendar maker and counted as one of the leading German. In 1680 he discovered a comet with a telescope for the first time: Komet C/1680 V1, called Kirch's comet. In 1681 he discovered the Wild Duck Cluster M 11. In 1686 he went to Leipzig. Together with the farmer and astronomer Christoph Arnold he observed the comets of that year. In the same year he discovered the Mira variable χ Cygni. He also dedicated much time to observing the double starMizar. He introduced three new constellations, the ″Globus cruciger″, the ″Electoral Sword″ and the Sceptre of Brandenburg, which however were not recognized and adopted by the International Astronomical Union. Via Arnold he met his second wife Maria Margaretha Winkelmann, who had learnt astronomy from self-study and from Arnold. While jointly observing the comet of 1702, they discovered the globular cluster M 5. In 1699, he had observed comet 55P/Tempel-Tuttle but this observation was not recognized until later analysis by Joachim Schubart. For a long period, he was unable to find employment, so he had to earn his living through the publication of Almanacs/ Calendars. He was assisted in the calculations by his second wife and their children. A few series of almanacs appeared across several decades. For a time, he published up to 13 almanacs a year, a few appearing under pseudonyms and he also continued established almanacs from other authors under their name. As examples could be cited Christian-, Jewish- und Turkish-Almanac, the Gipsy-Almanac the Sibylla Ptolemaein, a Gipsywoman from Alexandria in Egypten, the Astronomischen Wunder-Kalender, the Wahrhaftigen Himmels-Boten, the Gespenster- und Haushaltungs-Kalender by Johann Friedrich von Rosenfeld / Der Astronomiae Ergebener and from 1700 the various Academy Almanacs as 'Astronomer Royal' in Berlin. It is only recently that the importance of the Kirch's Almanacs has been recognized for the distribution of ideas of the Enlightenment and Pietism to the wider population. The functions of almanacs are Information, Education and Discussion. Kirch's Calendars are marked additionally for the announcement of both their own results as well as the results from abroad. A few almanacs anticipate the Astronomisches Jahrbuch. Further aspects are the transmission of new ideas to ordinary people in conjunction with a growing distancing from astrological superstition and criticisms of orthodox beliefs. The accompaniment to all almanacs Zugaben / Oder Astrologisches Bedencken / von dem Lauff und der Wirckung des Gestirnten Himmels / … had been demanded by the publishers, as otherwise the almanacs did not sell well. Astrological ideas were still not fully overcome, he attacked the practice of astrological forecasting and mendacity of many almanac makers of his time as being a sin against God, especially prophesies regarding war and peace. Since 1675 he pursued the idea of founding an Astronomical Society in Germany. It was to be open to all astronomers independent of nationality or religious persuasion. He projected the idea that all astronomers should send their observations to a central location where they could be published as soon as possible. He considered Frankfurt am Main to be the ideal location, for one because of the Messe and on the other hand because of the easy connection to the Netherlands via the Main and Rhein. The planned society should also serve to coordinate the observing of astronomical events such as eclipses and transits of planets. As examples could be mentioned the transit of Mercury on 31 October or 1 November 1690, which he organized in quasi-military fashion. However he appears to have made no concrete steps to set up such a society. Then in 1700 he was appointed the first astronomer of the Royal Society of Sciences in Berlin on 10 May by Prince-electorFriedrich III. of Brandenburg. The founding of the associated Berlin Observatory was a reaction to the new national observatories in Greenwich, Paris and St. Petersburg. To finance the Academy, the Prince-Elector conferred the "Kalenderpatent" on it. Kirch and his wife therefore were obliged to also finance the Academy by their almanac calculations. After his death, his wife continued the almanac calculations. His son Christfried Kirch became director of the Observatory in 1716. When Prussia incorporated the new province of Silesia in the 1740s, a further almanac was needed to be drawn up for the Catholics, for that issue the Academy employed his daughter Christine Kirch. Since 1700, two calendar variants were in force in the German Reich: the Gregorian Calendar in the catholic, the Verbesserter Reichskalender in the Protestant regions, however the latter differed from the former solely in respect of calculation of the date of Easter. The crater Kirch on the Moon and the asteroid6841 Gottfriedkirch are named after him. Kirch studied the double star Mizar. He died at Berlin at the age of seventy.
