|Right Ascension|| 17 : 30.6 (h:m)
|Declination|| -21 : 29 (deg:m)
|Distance|| < 20,000 (ly)
|Visual brightness|| - 2.5 (mag)
As of the time of writing (February 1998), this was the last supernova which was definitely observed in our Milky Way Galaxy. It was discovered on October 9, 1604, when it was already brighter than all stars in the sky, by several persons including Brunowski in Prague (who notified Kepler), Altobelli in Verona, Clavius in Rome, and Capra and Marius in Padua. Kepler first saw it on October 17, and started a systematic study of the phenomenon, inspired by Tycho's work on the supernova of 1572.
Initially as bright as Mars, the supernova brightened up and surpassed Jupiter in brilliance within a few days. According to a study of Baade 1943, the peak brightness was perhaps close to magnitude -2.25. It was still about as bright as Jupiter when it became invisible in twilight of November. At its reappearance in January 1605, Kepler found it still brighter than Antares, and it remained visible until March, 1606, after a naked-eye visibility of 18 months. From its light curve, it was suspected that this had been a type I supernova.
Our image is a drawing of Kepler of the Supernova 1604 in the foot of Ophiuchus. This image was taken from the Out of This World: The Golden Age of the Celestial Atlas Exhibition of Rare Books from the Collection of the Linda Hall Library.
In 1941, astronomers used the Mt. Wilson 100-inch telescope and identified the gaseous remnant of Kepler's supernova, a faint fan-shaped nebulosity about 40 arc seconds in extent, consisted of filamentsand bright condensations with a total brightness of about magnitude 19. This young supernova remnant has been cataloged as 3C 358 (from its radio emission) and G4.5+6.8 (in David Green's SNR catalog).
The distance of Kepler's supernova is not known, but Burnham estimates, from the assumption of an absolute magnitude -16, an upper limit of about 20,000 light years; absorption could significantly reduce this number though.