Consideratio & observatio cometae aetherei astronomica qui anno MDLXXX mensibus octobri, novembri et decembri in alto aethere apparvit

XII.

...of the calculation: I remember, however, that I had not looked back at the sign and stars of Cetus, near which I first saw the Comet, since August with any singular notice, nor to the later stars of Eridanus, from which it perhaps ascended. On the 2nd day of October, however, when I happened to be looking at the stars that are the fifteenth and sixteenth in the asterism of Cetus, I observed, struck with fear in my mind, the star of the Comet associated with them.

The Comet on October 2nd near the stars of Cetus.

Retrograde motion of the Comet. Oblique path, and finally curved.

From that place, in the following days, it ascended against the succession of the signs through 4 inform stars of Pisces, leaving the asterism of the following fish, the hand of Aquarius toward the south, but the head and the muzzle of Pegasus toward the north; it passed through the stars in the nostrils of the little horse, with the eastern one of them reclined to the north and the western to the south, at which place it crossed the path of the Comet of the year 1577, which, approaching there from Sagittarius through Antinous, passed through (although it is claimed by some to have been much more northerly, when in fact on the 2nd and 3rd of December in the year 1577 everyone saw by manifest experience how exactly it passed through the middle of them). Afterward, this Comet, proceeding through Delphinus, was not much further south with its head than the tip of the Arrow, and its tail indeed covered all its stars in that transit. From there it crossed the Eagle. But afterward, when it had passed the colure of the solstices, it reversed its motion toward the head of Hercules, or Engonasin, through the shoulder of Ophiuchus and the left side, as if it were about to descend to the sea. It traversed during the time it was observed by me 4 signs of the zodiac with almost a half, namely the former part of Aries, Pisces, Aquarius, Capricorn, and almost all of Sagittarius. It was slow from the beginning, then gradually proceeded with a faster motion, fastest around the beginning of Pisces, at which place it completed over 5 degrees in one day; afterward, however, it slowed again, until finally, turning itself toward the equator, toward the end it seemed...