Comet C/2021 A1 (Leonard)—IV

It’s been awhile since the last post about the comet—but cloudy skies with lots of rain and snow have made observations difficult. Finally, we had a break in the weather on New Year’s Day and I was able to capture additional images.

The comet has dropped lower in the sky making it difficult to get good images because the comet is now located in the band of twilight glare. Only at the end of astronomical twilight is the sky dark enough but by this time the comet is very low on the horizon leaving only minutes to shoot until it sets.

Below are two images of the comet. The first is a set of images taken between 1832 and 1850 MST. The best 30 images were combined and averaged in Starry Sky Stacker then histogram stretched using rnc-color-stretch. Individual images were shot at 85mm, ƒ/4, ISO 100, and 15 seconds. The resulting image shows the tail extending nearly to the upper left corner.

Comet C/2021 A1 (Leonard) at 1832–1850 MST 01 January 2022.
Comet C/2021 A1 (Leonard) at 1832–1850 MST 01 January 2022.
Comet C/2021 A1 (Leonard) at 1901 MST 01 January 2022.
Comet C/2021 A1 (Leonard) at 1901 MST 01 January 2022.

The second image is a single image taken at 1901 MST at 85mm, ƒ/1.8, ISO 500 and 30 seconds. This image shows how close the comet was to the horizon. The glow at the bottom of the image is the light dome from Phoenix about 200 km to the south.

The comet is moving away from us and lower in the sky. I’m not certain I will be able to get another chance to capture any images. For those in the southern hemisphere, the comet is better placed in the night sky for viewing and photography and there have been some amazing images captured. Spaceweather.com noted that “…Intense solar heat has given the comet one of the most beautiful tails astronomers have ever seen…

 

Comet C/2021 A1 (Leonard)—II

Comet C/2021 A1 (Leonard) is currently visible in the southwest evening sky for a short period after sunset. Evening twilight makes it difficult to see the comet with the unaided eye. Even in binoculars it is a faint object. On the other hand, a short exposure on a camera will reveal the comet and its tail.

A nearly-full Moon illuminates the snow-covered San Francisco Peaks as the comet sets in the evening twilight.
A nearly-full Moon illuminates the snow-covered San Francisco Peaks as the comet sets in the evening twilight.
Telephoto view of the comet and tail. (Stack of 13x15seconds, 300 mm, f/8, ISO 400.)
Telephoto view of the comet and tail. (Stack of 13x15seconds, 300 mm, f/8, ISO 400.)
Comet peaking out between the clouds.
Comet peaking out between the clouds.

Finally, here is a time-lapse of the comet on 17 December 2021 from 18:16:48–18:21:08 MST. It moves quite a bit in just a few minutes.

Time lapse of the comet.

The comet will reach its highest elevation above the horizon this week and then begin to slowly drop towards the horizon again.

Comet C/2021 A1 (Leonard)—I

There is a new comet currently visible through telescopes, binoculars and long-exposure photographs in the morning skies—and there are expectations that the comet will become bright enough to be seen with the unaided eye in the coming weeks.

Comet C/2021 A1 (Leonard) with M3 and two meteors at 0450 MST 03 December 2021.
Comet C/2021 A1 (Leonard) with M3 and two meteors at 0450 MST 03 December 2021.

Comet C/2021 A1 (Leonard) was discovered by G. J. Leonard at the Mount Lemmon Observatory in early January 2021. The comet will make its closest approach to Earth on 12 December 2021 (~35 million km). It will make its closest approach to the Sun on 3 January 2022 and then will head out of the Solar System.

It has a current estimated magnitude of around +6 and is expected to brighten to +4 as it nears the Sun. Some forecasts call for a brightening to magnitude +2 making it visible even in the twilight hours. It is becoming likely that this will be the brightest comet of 2021.

This was my first attempt to photograph the comet. It was barely visible in binoculars (7×50) but was easily seen with even a short exposure on the camera. I set the camera to take 60 second exposures for an hour—at which time astronomical twilight would begin to brighten the eastern sky.

The photograph at the top was taken just a few minutes after the start of the session and shows two meteors (one bright and the other fairly dim) passing through the same portion of the sky as the comet. Also visible in the photograph is Messier 3 (M3 or NGC 5272), a globular cluster made up of around a half million stars.

Photo details: Nikon D750, Nikkor 180mm ED AI-S, ƒ/2.8, ISO 1600, 60 seconds; tracking with an iOptron Sky Tracker.

Below is a time-lapse animation of the images collected during that hour. The comet is moving at an ultrafast speed of ~71 km/second relative to Earth and that fast motion is easily seen in the animation.

Time-lapse imagery showing the motion of the comet from 0450–0550 MST on 03 December 2021.

I hope to have more opportunities to photograph this comet in both the morning sky and later in the month in the evening sky—especially if it brightens significantly.

Lunar Eclipse of 18–19 November 2021

The Lunar eclipse of 18–19 November was considered a “partial eclipse” but with 97% coverage it was pretty close to a total eclipse. But not quite. That last 3% of the illuminated limb of the Moon was enough to make photography a challenge because its brightness significantly overwhelmed the dim red of the remainder of the lunar disk as well as the nearby stars.

Lunar eclipse with the Pleiades and Hyades star clusters.
Lunar eclipse with the Pleiades and Hyades star clusters.
Lunar eclipse.
Lunar eclipse.

What made this eclipse noteworthy is the proximity of the Moon to both the Pleiades (M45) and Hyades star clusters.

I used an Nikon 80–200mm telephoto zoom lens for this astrophotography session. Set to 200mm it was possible to capture (barely) both the Moon and Pleiades. Set to 80mm it was easy to capture all three objects. This legacy lens from Nikon is still a very useful astrophotography lens for me—not least because it has a hard stop at infinity making nighttime focusing simple.

Complicating the setup—and there’s always a complication—was the presence of high, thin clouds streaming across the sky. These clouds muted the brilliance of the stars but also created an illuminated area surrounding the Moon. To capture both the bright uneclipsed sliver of the Moon as well as the nebulosity in the Pleiades required shooting a variety of exposures that could be blended later. Even this was not as easy as I had hoped and I tried different methods (e.g., layers with masks; high dynamic range blending; dodging and burning, etc.) until I was finally satisfied with a good but less than stellar (get it? stellar?) image.

Here are two images. The zoomed in and highly cropped image was shot at ISO 800, ƒ/8, and 4 seconds at a focal length of 200mm. The wider field of view was shot at 80mm, ISO 800, ƒ/8, and at shutter speeds of ½, 1, 2, 4, 8, 15, and 30 seconds. HDR blending was done using Lightroom 6 and then further tweaked using various tools to brighten the stars while keeping the Moon dark.

Moon-Venus Conjunction

A few days ago, the thin crescent Moon passed close to the planet Venus in the evening twilight sky. Conjunctions such as this repeat at roughly one-month intervals so this is not a rare occurrence—just a beautiful one.

Conjunction of Venus and the Moon.
Conjunction of Venus and the Moon.

The crescent Moon is ~2.4% illuminated by the direct light of the Sun; the remainder of the Moon is lit by Earthshine which is bright enough to show detail on the shadowed face of the Moon. Leonardo da Vinci explained the phenomenon in the early 16th century when he realized that both Earth and the Moon reflect sunlight at the same time. Light is reflected from Earth to the Moon and back to Earth as earthshine.