Comet C/2023 A3 (Tsuchinshan — ATLAS)

I had heard multiple times throughout the year that a bright new comet, C/2023 A3 (Tsuchinshan — ATLAS), was approaching us. Unfortunately, I missed the moment of its perihelion passage and the first few days when it was observable in our latitudes. Later, I saw photos of this remarkable visitor to the Solar System on social media. I had to urgently catch up while there was still a chance, as the comet is rapidly moving away from the Sun and losing brightness with each passing day. Its observation is also time-limited: just about an hour after sunset before it dips too low on the horizon.

Only on the second day after recalling the comet did I get a chance to photograph it. The sky was overcast all day, and only briefly cleared after sunset. Even through thin, translucent clouds, there might not have been another opportunity. I quickly gathered my equipment and went to shoot: the conditions for observation would only worsen with each passing day.

Comet Information

Comet C/2023 A3 was discovered in January 2023 simultaneously by the Chinese Tsuchinshan Observatory and the ATLAS automated survey system. It moves in an elongated orbit around the Sun and belongs to long-period comets. The comet passed its perihelion (closest point to the Sun) on September 27, 2024, approaching the star at a distance of about 0.39 AU (58 million km) — slightly farther than Mercury’s orbit. It reached its peak brightness in early October 2024 and, under ideal conditions, could even be visible to the naked eye.

The sky quality left much to be desired: a thin veil of clouds, the Sun not yet fully set below the horizon, and urban light pollution. The conditions for shooting were far from ideal. The comet was nearly impossible to discern with the naked eye. I knew exactly where to look, but in the sky, it appeared more like a faint star — all due to the mentioned factors. There was little time for shooting: barely less than an hour. With each minute, the comet sank lower toward the horizon and became less noticeable.

I took several series of photos using a Canon EOS 550D camera with an 18-55mm lens on a stationary tripod. Even in unprocessed frames, the comet was already easily visible. After processing the first series, shot on the evening of October 20, I managed to get an excellent shot that might not have happened due to cloudiness. I got a bit lucky, though the thin clouds did affect the image quality. The reddish glow in the photo is the light of the not-yet-fully-set Sun.

Interestingly, these “unfavorable” conditions unexpectedly worked in my favor. The red glow of the sunset added drama to the frame, the thin layers of clouds made the sky more textured, and the comet’s long tail stood out even more brightly against this soft glow. The result was perhaps the best astronomical photo of the comet, with a unique atmosphere.

Observation Conditions in Dnipro (Ukraine)

For observers in Dnipro, the best visibility conditions occurred between October 10 and 25, 2024. The comet could be spotted in the evening sky, low above the western horizon. The observation window lasted only about 40–60 minutes after sunset before the celestial body dropped too low. Its altitude above the horizon during this period did not exceed 10–12°, so choosing a location with an open horizon and minimal urban light pollution was crucial for successful observations.
In clear skies outside the city, the comet appeared as a hazy spot with a faint tail, noticeable when photographed with long exposures. However, urban light pollution significantly hindered visual observation, making photography the primary way to capture this celestial phenomenon.

The observations didn’t end there. The next attempt took place two days later, on October 22. This time, the goal was to capture the comet using a Jupiter-37A lens and to shoot a timelapse against the backdrop of a residential area. I didn’t bother too much with the shooting location and filmed right in my yard: there was neither the opportunity nor the desire to run to the garden with a telescope.

This is how the comet looked directly above the houses. Honestly, I expected a more striking effect. Strong local light pollution noticeably interfered: the sky appeared bright, and the comet was harder to distinguish. No processing tricks could fully salvage the image. Urban light is truly a great enemy of astronomical photography.

This photo was taken with the Jupiter-37A lens and a motorized equatorial mount EQ3-2 instead of a stationary tripod. Such a mount, typically used with telescopes, allows the camera to “track” the motion of a celestial object, significantly increasing the exposure time. This is especially important for long-focus lenses: for example, the Jupiter-37A has a focal length of 135 mm. Without a mount, you can shoot for no more than 2 seconds at this focal length, but with the EQ3-2, I managed to increase the exposure to one and a half minutes.

Here’s a close-up photo of the comet. A faint tail ahead of the nucleus is barely visible here.

Finally, the last photo of comet C/2023 A3 (Tsuchinshan — ATLAS) was taken two days later, on October 24. For this shoot, I chose a new location — the Diiivka Floodplains area. Climbing a mound that offers a wide view of the Diiivka residential sector, I wanted to try capturing the comet against the backdrop of this panorama. Additionally, a large series of frames was shot for a timelapse.

By this time, the comet’s brightness had noticeably decreased, but it was still clearly visible in the images. Unfortunately, urban light pollution was again an issue: in addition to the Diiivka panorama, the glow of streetlights and overall illumination reduced the image’s contrast.

Nevertheless, I’m more than satisfied with the result.

All the photos and timelapses from all shooting sessions were compiled into a single video. It also includes a brief story about the comet and footage from different observation days with shooting parameters noted. You can watch it here or on my YouTube channel.

Comet C/2023 A3 (Tsuchinshan — ATLAS)

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