Comet Tsuchinshan-ATLAS (C2023 A3)

C/2023 A3 (Tsuchinshan–ATLAS) (or Comet Tsuchinshan–ATLAS or simply Comet A3) is a comet from the Oort cloud discovered by the Purple Mountain Observatory in China on 9 January 2023 and independently found by ATLAS South Africa on 22 February 2023. The comet passed perihelion at a distance of 0.39 AU (58 million km) on 27 September 2024,^] when it became visible to the naked eye. Tsuchinshan-Atlas peaked its brightest magnitude shortly after passing the Sun at 9 October, with a magnitude of −4.9 per reported observations at the Comet Observation Database (COBS). Τhe closest approach to Earth was on 12 October 2024, at a distance of 0.47 AU.

The comet has a retrograde orbit, lying at an inclination of 139°. Τhe comet has an orbital period of many million years.