2023a3 20241001 1900 mmattiazzo

Perihelion +4 days

C/2023 A3 Tsuchinshan-ATLAS on 2024 October 1 at 18:50UT. using a Canon 6D + Sigma lens at 50mm f/2.8. iso1600. 15 sec

animation at https://southerncomets.info/

A visual estimate at 19:00UT using 8x40mm binoculars was magnitude 2.1 with 4' coma and strong degree of condensation DC7, tail length now 15 degrees in PA255.

Comparison stars Regulus (1.4), Nu Hydra(3.2). Comet magnitude was corrected for atmospheric extinction using the average table.

Corrected Naked eye estimate was mag 1.9, with a tail 10 degrees long using averted vision. Not obvious to the eye. 

Low altitude (5 degrees) and slight haze.

Comet head was kept naked eye observable until 40 minutes prior to sunrise. (sun 8 degrees below horizon)

Distance to Sun = 0.41AU (61 million kms)

Distance to Earth = 0.73AU (110 million kms)

solar elongation = 21 degrees.

 

At this rate of tail growth, I predict easily 30 degrees by mid-October.