47P/Ashbrook–Jackson

47P/Ashbrook–Jackson is a Jupiter-family comet with an 8.35-year orbit around the Sun. It is the only comet discovered by Joseph Ashbrook and the third and final one by Cyril V. Jackson.

Observational history

The comet was first spotted by Joseph Ashbrook while examining a photographic plate exposed from the Lowell Observatory while observing the asteroid 1327 Namaqua on the night of 26 August 1948. At the time it was a diffuse, 12th-magnitude object with a tail about a degree in length, located within the constellation Aquarius. It was independently discovered by Cyril V. Jackson from the Yale-Columbia station at Johannesburg just a few hours later.
Orbital calculations by Leland E. Cunningham in 1948 led to the successful recovery of the comet by Michael P. Candy on April 1955. Since then, comet Ashbrook–Jackson was observed on every apparition, with the most recent observations recorded as recently as 2025.

Physical characteristics

Despite a large perihelion distance of, the comet typically reaches magnitude 12 on each observed apparition since 1948, making Ashbrook–Jackson one of the intrinsically brightest short-period comets ever known.
Its nucleus is estimated to have an effective radius of around, rotating on its axis once every hours.