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

November 3, 2024 / 2 Comments

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.

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.

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.

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.

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.

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.

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.

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.

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!

A Very Foggy Morning

October 5, 2023

Fog at sunrise in the Mormon Lake Basin.

A few days ago we had a cold front move across the area and overnight temperatures fell below freezing for a few hours in the higher terrain. It turns out that October is a good month for fog formation from these first frontal incursions. Area lakes still have relatively warm water from the recently ended summer. The passage of the cold air over the warm water allows for increased moisture flux from the warm water into the colder air that increases the dewpoint (and relative humidity) and can result in fog. Also, the shorter days–and longer nights–allows radiation fog to develop in the valleys.

Fog in the Mormon Lake basin with a colorful but diffuse glory.

A small sailboat lies at anchor on a foggy morning at Upper Lake Mary.

With that in mind, I found myself driving past Lake Mary to Mormon Lake before sunrise on Tuesday morning. As I approached Lake Mary visibility dropped quickly to 1/4 mile, then 1/8 mile, and then 1/16 mile. Visibility improved once I passed both Lower and Upper Lake Mary. At Mormon Lake, there was fog swirling in the basin and the rising Sun was just starting to illuminate the summits of the San Francisco Peaks.

After the fog dissipated in Mormon Lake, I returned to Lake Mary where the fog was still present and I was able to capture fogbows plus a nice photo of a sailboat anchored in the lake.

Time-lapse video of the swirling fog in the Mormon Lake basin.

Time-lapse video of the swirling fog and glory in the Mormon Lake basin.

The time-lapse videos show remarkable motion of the swirling for over Mormon Lake as well as the colorful but diffuse glory that was present.

A very fun morning.

Fog definitions from Weather.gov:

(1) Steam fog (arctic sea smoke). Steam fog forms when water vapor is added to air that is much colder, then condenses into fog. It is commonly seen as wisps of vapor emanating from the surface of water. This fog is most common in middle latitudes near lakes and rivers during autumn and early winter, when waters are still warm and colder air masses prevail.

(2) Radiation fog (ground or valley fog). Radiational cooling produces this type of fog. Under stable nighttime conditions, long-wave radiation is emitted by the ground; this cools the ground, which causes a temperature inversion. In turn, moist air near the ground cools to its dew point. Depending upon ground moisture content, moisture may evaporate into the air, raising the dew point of this stable layer, accelerating radiation fog formation.

Three Planets and the Moon

July 23, 2023

A few days ago the waxing crescent Moon joined the planets Mercury, Venus, and Mars in the evening sky. A few clouds and the reflection of the evening sky in the lake added a bit of color to the scene.

Mercury, Venus, Mars, and the Moon in the evening sky.

Mercury, Venus, Mars, and the Moon in the evening sky (with labels).

Screen capture from Stellarium.app showing the positions of the planets and Moon in the evening sky.

Afterwards, I stayed around to watch the rocket launch described in the previous post.

The Lakes are Full of Water

May 10, 2023

The upside to the epic Winter we recently experienced is the tremendous amount of snow melt that filled many of the lakes across northern Arizona. Over the past several weeks we have visited several of these by car, mountain bike, running, and hiking.

Upper and Lower Lake Mary (27 April 2023).

This is one of my favorites. It shows Upper Lake Mary, a portion of the spillway, and Lower Lake Mary. It’s also nice that there is a nice mirror reflection of the trees in the water. This shot is only possible when both lakes are full.

Earlier we had visitied Marshall Lake. It’s not as full as it was a few years ago but considerably better than the past several years.

Marshall Lake, Coconino National Forest (20 April 2023).

We did a trail run along the Arizona Trail on top of Anderson Mesa and visited Prime Lake and Vail Lake, both with lots of water.

Prime Lake, Coconino National Forest (24 April 2023).

Vail Lake on Anderson Mesa, Coconino National Forest (24 April 2023).

Here are some additional images of Lake Mary taken on various days in April.

The outlet on Upper Lake Mary and inlet on Lower Lake Mary.

We rode our mountain bikes up Schultz Pass Road to Schultz Tank. It has been a small puddle the past two seasons but is once again full.

Finally, we did a short hike through the upper portions of Pumphouse Wash to this set of cascades.

Cascades along the upper portions of Pumphouse Wash, Coconino National Forest (03 May 2023).

Series of cascades that terminates in a large and deep pool on Pumphouse Wash.

The snow melt is done and we are now in our dry season. Lake levels and stream flows will diminish until the summer rainy season starts in July.

Sunrise, Sunset, Rainbows, and Fog

August 18, 2022

The North American Monsoon continues to bring convective activity to much of northern Arizona on a daily basis. There have been plenty of opportunities for colorful sunrises and sunsets as well as rainbows and even some fog.