C/2000 A1 (Montani) was the first new comet discovery of the 2000s. It was found at the Spacewatch 0.9-m telescope by Joe Montani on 2000 January 12.

This is a comet with a very distant perihelion, and it will not approach nearer to the sun than 9.74 AU, which is 0.2 AU further from the sun than Saturn. Perihelion is 2000 July 21. At an even greater distance when discovered, the comet did not display much "activity" (outgassing and release of dust to form "coma" and a tail). The first sign that the object was unusual was its very slow motion, moving only 1/4 the rate of Main Belt asteroids in the same region. This is always a cue to the observer to look for cometary activity in such an object. Indeed, Spacewatcher Montani could see a small and faint envelope of light around a central brighter core in the images, but only in two of the three "repeats" of (or "passes" over) the region containing the object. More images were needed. Montani observed the object again on Jan. 13, and could see coma in all three passes taken over the object that second night. He alerted astronomers at other telescopes on Kitt Peak, and obtained confirmation of the object as a comet through observations by Susan Kern at the Steward Observatory 2.3-m telescope, and Wendy Shook at the WIYN 3.5-m on January 13.

When a preliminary orbit for the comet was generated and positions of the comet were calculated backwards in time before the discovery date, it was found that Spacewatch had some pre-discovery images of the comet from January 5 by Spacewatcher Nichole Danzl, and then the MPC also linked the comet with an object that the LINEAR survey telescope in New Mexico had registered as a moving object on January 4. In only three or four days since discovery, there was then about a nine-day arc to work with, and the orbit and ephemeris became quite secure. As of 2000 May 1, there were 85 observations of the comet accepted by the MPC and used in refining the constants of the comet's orbit. In September of 2000, the comet will be observable again and should appear as an 18.5 magnitude slow-moving object in the constellation Cancer.

The comet may be making its first trip near the sun and so it could be important to study via spectroscopy since the comet's materials may not be much modified by the warmth and radiation of sunlight, and may thus contain "pristine" samples of matter, preserved since the formation of the solar system.