2024 December 17

Prospects for C/2024 G3 (ATLAS)

Nick James

C/2024 G3 was discovered by the ATLAS survey on 2024 April 5 using a 0.5-m, f/2 Schmidt at Rio Hurtado, Chile (CBET 5384). At the time of discovery it was a 19th magnitude asteroidal object in the far south constellation of Octans. Subsequent observations showed it to be cometary with a very small perihelion distance.

The latest orbit shows that the comet is probably a new visitor to the inner Solar System (the orbital eccentricity is almost exactly 1.0) and that it will arrive at perihelion on 2025 January 13 at a distance of only 0.093 au (MPEC 2024-X74). It will be strongly heated and may not survive, but if it does, it may be an impressive object in the evening sky from the southern hemisphere after perihelion. Unfortunately the observing geometry is poor and even if the comet gets bright its tail will be pointing away from the Earth. It may get bright enough to be seen in daylight around the time of perihelion but such observations can be dangerous and should only be attempted if you are an experienced observer.

The comet is a southern hemisphere object as shown in the two plots below which show the altitude of the comet above the horizon when the Sun is 6 degrees down. At present the comet is a 7th magnitude object visible very low in the morning twilight from latitudes south of the equator. It is brightening rapidly as it approaches the Sun but its elongation, which is currently around 20 degrees is decreasing as it moves towards perihelion. The latest images are on the Comet archive page for C/2024 G3. We should be able to follow it in the morning sky until early January.

It could potentially be a nice imaging target in the evening sky post-perihelion but probably only from the southern hemisphere.

Current predicted total magnitude plot produced by Jonathan Shanklin (https://people.ast.cam.ac.uk/~jds/)