Comet C/2023 A3 (Tsuchinshan-ATLAS)–Evening Observations

A previous post showed many images of Comet C/2023 A3 (Tsuchinshan-ATLAS) taken when the comet was visible in the morning sky. The comet then moved between the Earth and Sun making it difficult to see. A period of 10 days passed between my last morning images and my first evening images.

At first, the comet was difficult to see in the bright evening twilight and the presence of the Moon made it even more difficult. But  each day the Moon rose later in the evening and the comet rose higher in the western sky. I was able to take advantage of clear skies and shot photographs on eight days. Here are some of the best photographs from those sessions.

13 October 2024

I had already shot images of the comet while looking to the east across Ashurst Lake when it was a morning object. Now it was time to shoot looking to the west across the Lake. The comet was very bright and easy to see. I also shot a long sequence of images to create a time-lapse video of the comet setting in the west.

Comet C/2023 A3 (Tsuchinshan-ATLAS). 13 October 2024.
Comet C/2023 A3 (Tsuchinshan-ATLAS). 13 October 2024.

Time-lapse video of the comet setting behind Ashurst Lake near Flagstaff, Arizona.

14 October 2024

The next evening I set up at the Arizona Snowbowl parking area–along with dozens of other comet watchers. It was fun to listen to folks admiring the comet and the joy from the kids when they were first able to spot it in the darkening sky. The anti tail was even easier to see on this night compared to the previous evening.

Comet C/2023 A3 (Tsuchinshan-ATLAS) from Arizona Snowbowl. 14 October 2024.
Comet C/2023 A3 (Tsuchinshan-ATLAS) from Arizona Snowbowl. 14 October 2024.

16 October 2024

The Moon was still a factor in the evenings but the comet was getting higher in the sky so it balanced out. On this evening I went to The Narrows at Upper Lake Mary since that section of the lake is oriented WSW-ENE. This meant I could photograph the comet above the water and get a reflection of it in the water. That worked out pretty well.

Comet and reflection in the still waters of Lake Mary. 16 October 2024.
Comet and reflection in the still waters of Lake Mary. 16 October 2024.
Comet and reflection in the still waters of Lake Mary. 16 October 2024.
Comet and reflection in the still waters of Lake Mary. 16 October 2024.

20 October 2024

A few days of clouds shut me down but by this day it was very clear and the Moon was no longer a problem. I opted to use a longer telephoto (180mm) for these shots even though it might truncate part of the tail. The anti tail is still visible but is much less striking than in earlier days.

Telephoto view of the comet. 20 October 2024.
Telephoto view of the comet. 20 October 2024.

21 October 2024

The comet was continuing to rise higher in the western sky and was closer to the Milky Way so I switched back to ultra-wide angle lenses to capture both. Bonus: I was able to again capture the comet and tail reflected in the waters of Lake Mary. For the very wide image shown here I did a composite. The first image had star tracking turned on to get sharp stars and comet; the second image had tracking off to get sharp foreground. These were then combined and blended in software.

Comet and Milky Way reflected in the still waters of Lake Mary.
Comet and Milky Way reflected in the still waters of Lake Mary.

23 October 2024

The comet continued to climb higher, become dimmer, and have a shorter tail as it moved away from Earth and Sun. I switched to a short telephoto (85mm) to shoot a sequence of images which were then stacked to reduce image noise. I was also able to use the sequence to create a short time-lapse video to show the movement of the comet over a period of about 45 minutes.

Comet and stars using a short telephoto lens. 23 October 2024.
Comet and stars using a short telephoto lens. 23 October 2024.

Time-lapse showing the motion of the comet against the background of stars. 23 October 2024.

25 October 2024

As the comet climbed higher it also was closer to the Milky Way and I again tried to get a shot with both features. This was taken with at 35mm focal length.

Comet and Milky Way. 25 October 2024.
Comet and Milky Way. 25 October 2024.

31 October 2024

As the comet retreats it is getting smaller in the sky and it is better to use medium length telephoto lenses. Here is an image taken with the Nikkor 180mm ED AI-S lens, a legacy, manual focus lens.

Medium telephoto lens used to image the comet. 31 October 2024.
Medium telephoto lens used to image the comet. 31 October 2024.

What’s next?

We are once again in a period of clouds. When skies are once again clear the comet will be much farther away, smaller, and dimmer. At this point, it will require longer exposures and bigger telephoto lenses. It should be fun!

Comet C/2023 A3 (Tsuchinshan-ATLAS)–Morning Observations

Comet C/2023 A3 (Tsuchinshan-ATLAS) has been in the headlines and the morning sky for a few weeks. Yeah, some of the headlines and news articles are over-the-top but most of them are quite good. And the comet in the morning twilight has been fun to photograph.

Comet C/2023 A3 (Tsuchinshan-ATLAS) and Ashurst Lake, Flagstaff, Arizona.
Comet C/2023 A3 (Tsuchinshan-ATLAS) and Ashurst Lake, Flagstaff, Arizona.

I have taken photos on five different mornings over a nine-day period and have captured images of the comet growing brighter and the tail growing longer. On only one occasion was I able to see the comet with the unaided eye. On three occasions I was able to see it with binoculars. On all five mornings it was very easy to capture the comet with even very short exposures on the camera.

The comet is now getting very close to the Sun so I have suspended photography for a few days. When it reemerges in the evening sky I will once again start shooting photos. I hope it is easier to see during this phase.

I shot the comet with a few different focal lengths (50mm, 85mm, and180mm). I think the best images were with the 85mm f/1.8 lens (usually shot at f/2.8) as it gave a wide-enough view to include some foreground.

Here are some photographs and time-lapse video from the period 25 September through 03 October.

25 September 2024

This was my first attempt to photograph the comet. It was taken from the overlook on Mars Hill, home of Lowell Observatory, in Flagstaff. The comet is small and located in the upper middle of the photograph. I often shoot photos of astronomical objects in the eastern sky from this location because I can include much of the city.

Comet C/2023 A3 (Tsuchinshan-ATLAS) and the City of Flagstaff. (25 September 2024)
Comet C/2023 A3 (Tsuchinshan-ATLAS) and the City of Flagstaff. (25 September 2024)

26 September 2024

I was planning on returning to Mars Hill but smoke from a managed wildfire suggested I should try elsewhere. I ended up at the Mormon Lake Overlook. The first image is a stack of 16 images taken over the course of about five minutes. The stacking increases the signal, reduces noise, and allows more stretching of the histogram to pull out the faint details.

The video was taken from the same set of images but without any cropping. The camera was mounted on a star tracker so that the comet remained fixed in the images.

A stack of 16 images taken over the course of about five minutes. (26 September 2024)
A stack of 16 images taken over the course of about five minutes. (26 September 2024)

Time-lapse video of the comet rising above the eastern horizon. (26 September, 2024)

28 September 2024

With some smoke still present I returned to the Mormon Lake Overlook on this morning. I was disappointed at the clouds but afterwards decided that I really liked the image of the clouds partially obscuring the comet tail.

Clouds partially obscure the tail of the comet. (28 September 2024)
Clouds partially obscure the tail of the comet. (28 September 2024)

October 01 2024

I went to Ashurst Lake for this photo session with the hopes of catching a reflection of the comet tail in the calm waters of the lake. I was not disappointed!

In the first image, the comet has not risen above the horizon but the comet tail is strikingly visible in the sky and reflected in the water. In the second image, the comet has barely cleared the trees, the tail is still quite bright, but the reflection on the water has dimmed. Next, the waning crescent Moon rises–and is partially behind a cloud–as the sky brightens making the comet’s tail more difficult to see. The final image is a stack of six images and cropped to show only the comet and tail.

The tail of the comet is reflected in the still waters of Lake Ashurt, near Flagstaff, Arizona. (01 October 2024)
The tail of the comet is reflected in the still waters of Lake Ashurt, near Flagstaff, Arizona. (01 October 2024)
The comet has risen above the trees and the tail remains strikingly visible while the reflection has dimmed.
The comet has risen above the trees and the tail remains strikingly visible while the reflection has dimmed.
The crescent Moon joins the scene in the eastern twilight. The sky has brightened making it more difficult to see the tail. (01 October 2024)
The crescent Moon joins the scene in the eastern twilight. The sky has brightened making it more difficult to see the tail. (01 October 2024)
Close up of the comet and tail in the bright twilight. (01 October 2024)
Close up of the comet and tail in the bright twilight. (01 October 2024)

October 03 2024

My goal on this morning was to shoot a long sequence of images so that I could produce a time-lapse video starting when the comet was below the horizon until twilight became too bright to see the comet. Again, I was at Ashurst Lake hoping for reflections or smooth water. Success!

The first image was taken ~14 minutes before the comet rose above the horizon but the tail is still easily visible.

The comet is below the horizon but the tail extends well up into the twilight sky. (03 October 2024)
The comet is below the horizon but the tail extends well up into the twilight sky. (03 October 2024)

Time-lapse video of the comet rising during the period 0503–0533 MST. (03 October 2024)

As I mentioned at the beginning, there have been many articles about the comet. I think this one from Sky and Telescope is one of the better ones. Also, EarthSky.org has published many beautiful photos of the comet.

The best is yet to come!