C/2023 A3 (Tsuchinshan–ATLAS) is a comet from the Oort cloud discovered by the Purple Mountain Observatory on 9 January 2023 and independently found by ATLAS South Africa on 22 February 2023. The comet will pass perihelion at a distance of 0.39 AU (58 million km; 36 million mi) on 27 September 2024, when it could become visible to the naked eye. [source: WikiPedia]

Ten days after my previous image of this comet, the sky was finally clear enough for yet another attempt. The comet was then in the constellation Ophiuchus (just south of Rasalhague) at a distance of 0.786 AU from the Sun and 0.730 AU from Earth.

It was clear that the comet had moved further away from us since my last image, as it had become considerably fainter. Exposures in RGB were 10 seconds (20 subs per filter) and 5 seconds in luminance (60 subs). The adjacent image shows a section of sky of about 2.5 x 2 degrees and was taken between 18:03 UTC and 18:21 UTC with a ZWO ASI1600MM Pro Cool and ZWO LRGB filters behind the SkyWatcher Esprit 80ED.

Stacked in APP 2.0.0 beta 29, post-processing in Topaz and PSP.

Click here for the full image.

After having spent several months in the day, the comet re-appeared in the evening in October. On 14 October 2024 weather permitted a full LRGB run. The comet was at the moment still in the constellation Virgo at a distance of 0.595AU from the Sun and 0.484AU from Earth.

Being much closer to both the Sun and Earth than last May exposures where much shorter. Per RGB-filter 20 subs of 5 seconds were taken, followed by 40 subs of 5s in luminance. Adjacent image shows a sections of the sky of approximately 2.5 x 2 degrees and was taken between 18:01UTC and 18:12UTC using a ZWO ASI1600MM Pro Cool and ZWO RGB filters behind the SkyWatcher Esprit 80ED.

Stacked in APP 2.0.0 beta 29, post-processing in Topaz and PSP.

Click here for the full image.

Within two months after I imaged 12P/Pons-Brooks there was a new comet to photograph: C/2023 A3 (Tsuchinshan–ATLAS). This one is not as large as the previous one, but still a nice view. On 25 May 2024 the sky was clear enough to do a full LRGB run. The comet was at the moment in the constellation Virgo at a distance of 2.4AU from the Sun and 1.8AU from Earth.

I started with 20 subs of 30 seconds per channel in RGB, followed by 40 subs of 30s luminance. Adjacent image shows a sections of the sky of approximately 1 x ¾ degrees and was taken between 21:45UTC and 22:40UTC using a ZWO ASI1600MM Pro Cool and ZWO RGB filters behind the SkyWatcher Esprit 150ED.

Stacked in APP 2.0.0 beta 17, post-processing in Topaz and PSP.

Click here for the full image.