KEPLER, Johannes (1571-1630) and BARTSCH, Jakob (c.1600-1633). Admonitio ad astronomos ... de raris mirisque 1631 phaenomenis. Frankfurt: Gottfried Tampach, 1630.

An extremely rare Kepler work: in which he was the first astronomer to successfully predict the transit of a planet across the Sun. Second separate edition. Kepler and his son-in-law, Jakob Bartsch, published this small pamphlet to promote the news of the predicted transits of both Venus and Mercury the following year, and hence also to drum up sales for the Rudolphine Tables. The prediction itself was extracted from the Ephemerides published in 1629. Kepler himself did not live to see the transits, but his prediction was heeded. At least three astronomers in Europe, including Pierre Gassendi, witnessed the transit of Mercury, becoming the first people to observe a transit and understand what they were witnessing. Gassendi published his observations in Paris in 1632. The 1631 transit of Venus was not visible from Europe. The first separate edition of this prediction was published in Leipzig a few months before this one, at Bartsch's instigation. He was en route to Frankfurt to arrange publication of this work when he decided to also publish in Leipzig. By the time he reached Frankfurt and this work was printed, Kepler had died. We locate no copies of either separate edition in the auction records of RBH or ABSA since 1975. Caspar 83.

Quarto (198 x 154mm). (First gathering toned, small marginal burnhole to A4, without final blank.) Modern wrappers (some leaves rehinged or needing rehinging).