2023a3 20240920 1917 mmattiazzo

Comet C/2023 A3 Tsuchinshan-ATLAS continues to brighten steadily.

Image attached on 2024 September 20 at 19:17UT using a C11 RASA f/2.2 + Canon 6D. iso1600 12x5sec. FOV 2x1 deg. North left from Swan Hill, Victoria, Australia.

1 week to perihelion

Visual estimate using 15x70mm binoculars m1 = 3.9, coma 4', DC 7, tail 35' in PA245. 

Coma appears strongly condensed with a parabolic hood.

Comparison stars Alpha Crt(4.2), Nu Hydra(3.2). Corrected for atmospheric extinction using the average table.

Moonlight and twilight interference as well as low altitude (6 degrees).

Distance to Sun = 0.43AU (64 million kms)

Distance to Earth = 1.20AU (180 million kms)

solar elongation = 20 degrees.