Halloween comet: It's not dead yet

 A clear night is hard to resist, and I wanted to try out another lens.  Comet C/2023 A3 is no longer visible to the unaided eye, and in fact it took some effort to find with binoculars.  It is no longer the spectacle it was less than a week ago.  The sky brightness was sqml=21.0 at the time of this image.  Camera: Olympus E-M1iii + Olympus 50mm f/2 ED macro lens.

Comet C/2023 A3, Halloween night, 8:13 pm MDT

In addition to the comet, there are a lot of other interesting objects in this field of view.  The same image is presented below with some labels added.

 

The three circled star clusters range from about 1200 to 1600 light years distant.  

To the right of the comet is Barnard's Star.  At a distance of just 6 light years, this star is the second closest to our sun after the three-star Alpha Centauri system.  It is a red-dwarf star with an estimated lifetime of over a trillion years.

Here are a couple cropped views:

 

As usual, click on any image to enter Gallery View, then right-click to get at the full-size version.

A nearby star, and last view of the comet (probably)

 This image is from Saturday night, 26 Oct.  There was a thin cloud or haze layer that acted as a natural diffusion filter, causing a halo around the brighter stars.   The sky brightness was about sqml=21.1.  The comet was just at the limit of visibility to the unaided eye.  It is still a fine view with binoculars or a small telescope.

Comet C/2023 A3, star cluster IC4665, and Barnard's Star (white circle)

 

The comet's tail in this image exceeds 5 degrees.  The star in the center is mag-2.8 Cebalrai, Beta Ophiuchus.  Just above that is the star cluster IC 4665.  In the upper left a white circle marks the position of mag-9.5 Barnard's Star, which appears as a reddish dot in the full-size image.  At a distance of 6 light years, this star is the second closest to our sun after the Alpha Centauri system.

The range of distances in this image remarkable:

• the comet is currently about 8 light minutes away
• Barnard's Star is 6 light years away
• IC 4665 is about 1400 light years away
  

Another faint star of interest is T Corona Borealis, the "Blaze Star", a recurrent nova that is expected to erupt imminently. Unfortunately, if it doesn't happen soon we may miss it.  In just a few weeks this constellation will be too low in the western sky as twilight fades.

Corona Borealis

The location of T CrB is marked with a white circle in this image.  Its normal brightness is magnitude 10.1.  When it erupts it is expected to be about as bright as Alphecca, the brightest star in this image.

Both of the above images were obtained with an Olympus E-M5iii + Olympus 75mm f/1.8 lens.

Another night, same comet, different lenses

 Not much new to say.  Another night of mediocre darkness, sqml=21.07.  Same comet, it's fading, but still fun to observe with optical aid.  I used 1.8x40 and 10x50 binoculars, and a 60mm f/6 telescope with an 18.2 mm eyepiece (20 x).

8:37 pm MDT.  Leica 15mm f/1.7 lens + softon filter.

8:42 pm MDT.  Comet (left) and Coma Berenices (right) setting over Bristol Head.

8:16 pm MDT. Olympus 75mm f/1.8 lens.

The tail extends over 5 degrees.

Venus setting. Still fun to watch.  Olympus 75mm f/1.8

Comet sinking into the murk

 These pictures of comet C/2023 A3 are becoming repetitive, so this may be the last set in spite of continuing clear skies.  The comet is still visible to the unaided eye as a faint smudge to the right of the Milky Way.  It is also still impressive in binoculars.

8:36 pm 23 Oct.  Olympus E-M1iii + Leica 9mm f/1.7 + sparkle-6 filter

8:23 pm MDT.  E-M1iii + Sigma 30mm f/1.4 + softon filter

8:04 pm MDT.  Sony A7iii + Nikon 180mm Ai-s f/2.8 ED.

This next image is an alternate version of the first one, with the contrast left open to show the extent of airglow in the western sky.  A vehicle traveling on Highway 149 was lighting up the flank of Bristol Head during this exposure.

Comet C/2023 A3 is fading but still visible

 When it gets dark enough to see the Milky Way, comet C/2023 A3 is also visible to the unaided eye.  Binoculars help, and it is still an impressive sight when magnified.  These images were obtained Tuesday night (22 Oct).  The sky was slightly darker, with sqml=21.1 toward the northwest.

Not yet dark enough: Venus setting into the trees on the flank of Bristol Head.

Milky Way, meteor, comet. 8:16 pm MDT.  Rokinon 24mm f/1.8 AF + softon.

Sony A7iii + Rokinon 24mm f/1.8, no filter.

8:27 pm MDT.  Sony A7iii + Nikon Ai-s 180mm f/2.8 ED.

The anti-tail is still faintly visible photographically, but it is spreading out and fading fast.  This view is similar to what I see in a 10x50 binocular.

Large prominences on the sun

 Sunpots are relatively scarce at the moment, but there are some impressively-large prominences visible.

These images were obtained yesterday (22 Oct) with a Lunt LS50THa double-stacked hydrogen-alpha scope and an ASI178mm camera.

false-color image.  The over-exposed disk is masked off.

The diameter of the sun is 109 times larger than the earth.  This next image gives a good impression of the relative sizes of these prominences compared to the Earth-Moon system:

The two white circles represent the Earth and Moon.

And here is an image of the full disk:

Comet C/2023 A3 shares the sky with the Milky Way

 Last night was the first clear night since the full Hunter's Moon on 17 Oct.  With no bright moonlight in the early evening, comet C/2023 A3 is easy to see in the western sky as twilight fades.  It is visible to the unaided eye and is a spectacular sight in binoculars.  The tail stretches about 14 degrees.

The measured sky brightness toward the north was sqml=21.0 mpsas.  In the camera there was strong red airglow visible.  In the images below, the layered airglow in the western sky is very distinct, although it is essentially invisible to the eye.

Comet and Milky Way.  8:05 pm MDT. Sony A7iii + 20mm f/1.8 G, no filter.

8:06 pm MDT.  Hoya Softon filter.

7:48 pm MDT.  Sony A7iii + Samyang 35mm f/1.8 AF + softon filter.

The Hoya Softon filter makes the relative brightness of the stars more apparent and the constellations become easily visible.

8:25 pm MDT.  Olympus E-M1iii + Sigma 56mm f/1.4 + softon filter.

8:13 pm MDT.  Olympus E-M5iii + Rokinon 135mm f/2.

The anti-tail is still visible.  It is becoming more diffuse and no longer aligns with the dust tail.  This image approximates the view I was seeing in 10x50 binoculars.

Click on an image to enter Gallery View and get access (via right click) to the full-size versions.

After the storm, moonset over Bristol Head

 After a long stretch of cloudy weather, Monday dawned clear.  The waning Hunter's Moon (19.5 d old) was setting over Bristol Head just after 11 am MDT.

E-M1iii + 40-150mm f/4 pro @ 93 mm

E-M5iii + AT60ED f/6 (360 mm)

cabin fever, waning Hunter's Moon

After the last view of comet C/2024 A3 on Tuesday (15 Oct) we have had five days of cloudy, rainy, snowy weather.  Last night while going out to gather firewood from the back porch I noticed the moon rising through a break in the clouds.  I went back inside and grabbed the only camera setup that was ready for action:  Sony A7 + Canon FD 300mm f/4 lens.

I was able to capture four quick frames, and that was it.

Waning Hunter's Moon rising above Snowshoe Mountain.

The moon is overexposed, but I really wanted to capture the clouds and trees in silhouette.

Day three of the comet

Once again the afternoon weather was dismal, with rain drumming on the roof.  And once again the clouds mostly cleared away after the sun set.  It is a common pattern, but it still seems like a miracle every time it happens.

I was able to pick up the comet with binoculars around 7:15 pm MDT.  If it wasn't for the nearly-full Hunter's Moon lighting up the sky, this would be a visually impressive comet.  We will have to wait until Saturday to see this comet without the moon in the sky at the same time.

I used two setups for these photos:  a Sony A7iii + Nikon Ai-s 105mm f/2.5 lens, and an Olympus E-M1iii + Olympus 75mm f/1.8 lens.

Venus setting over Bristol Head, 7:12 pm MDT.  Nikon 105mm f/2.5 @ f/4.

Venus is currently the brightest "star" in the sky at magnitude -4.  The next brightest is Jupiter, which rises about two hours after Venus sets.

7:28 pm MDT. Nikon 105mm f/2.5.

7:43 pm MDT.  Olympus 75mm f/1.8

The anti-tail is still clearly visible photographically.  It is hard to see unaided in the bright moonlight.

There is a fuzzy blob just up and to the right of the comet's head.  That is the globular star cluster M5.   You will need to open the full-size image to see that clearly.

7:50 pm MDT.  Olympus 75mm f/1.8

As usual, clicking on an image brings up Gallery View, from which the full-size images can be accessed (via right click).

A front-yard view of the year's best comet

 The prospects for comet viewing were not good today.  It was cloudy with intermittent rain during the afternoon and the clouds did not seem in a hurry to dissipate as sunset approached.  But, dissipate they did (mostly), just in time to find comet C/2023 A3 sinking toward the Bristol Head ridgeline.  This time, instead of driving to a remote site, I was able to step out the front door and set up a couple camera mounts.

7:33 pm MDT.  Olympus E-M1iii + 12-45mm f/4 pro @ 45 mm.  15 s, ISO 400.

Comet C/2023 A3 on the left, Arcturus on the right. 7:35 pm MDT.  32 mm.

Arcturus is the fourth brightest star in the sky.

7:36 pm MDT.  Sony A7iii + Nikon Ai-s 180mm f/2.8ED. 15 s, ISO 1600.

7:34 pm MDT.  Olympus E-M5iii + Rokinon 135mm f/2.  10 s, ISO 400.

This image appears tilted because the camera was mounted on an equatorial mount with the sensor axis aligned with celestial coordinates rather than the horizon.

The anti-tail is easily visible in this exposure.  The anti-tail is a trick of perspective.  It is the dust trail left behind in the comet's orbit, seen here edge-on as we pass through the orbital plane.

Evening comet, C/2023 A3 Tsuchinshan–ATLAS

The much-hyped comet C/2023 A3 Tsuchinshan–ATLAS is now visible in the evening sky.  I was able to spot it about 45 minutes after sunset (sunset was about 6:32 pm MDT), after waiting out some interfering clouds.

I had to travel to a viewing spot about 6 miles from home to get away from view-blocking mountain ridges and an overhanging cloud deck.  The compensation was getting to see deer, hear elk bugling, coyotes howling, and a red fox scampering across the road in my headlight beams on the return home.

 Venus and comet C/2023 A3.  7:37 pm MDT

The comet has a clear anti-tail.  7:42 pm MDT

7:45 pm MDT

Calm before the (ion) storm

 Auroras were visible in Creede on Monday (07 Oct).  On Thursday (10 Oct) the sky was on fire with the Northern Lights (at least, in the camera).  On Wednesday (09 Oct), the sky was relatively peaceful, with just some faint green airglow showing up in camera.  Sky brightness was dependent on direction: 21.01 mpsas to the north, 21.19 to the south.

Jupiter rising. Olympus E-M1iii + Laowa 7.5mm f/2 + Hoya Sparkle-6 filter.

Jupiter, at magnitude -2.6, is currently the second brightest "star" in the sky, after Venus, which is magnitude -4.0 in the western sky at dusk.

The next day after this image, this view would be lit up with a spectacular SAR arc.

Thursday night Northern Lights

A severe solar storm (G4 class) hit the Earth last night (Thursday 10 Oct).  Auroras were seen as far south as Mexico and Key West.  Viewing here in Creede was hampered by the first quarter moon (moonset was about 11:50 pm MDT) and some high thin clouds.  Visually the aurora was a faint pink glow in the north (from my location in Bristol Head Acres).  In the camera, however, it was a real spectacle.  

I used two cameras: a Sony A7iii + Sony Fe 20mm f/1.8 G lens, and an Olympus E-M1iii + Laowa 7.5mm f/2 lens.  Most images also employed a Hoya Sparkle-6 filter.

First the Sony images:

10:56 pm MDT

11:20 pm MDT

11:28 pm MDT

12:11 am MDT (11 Oct)

SAR arc over Snowshoe Mountain.  12:16 am MDT (11 Oct)

Now the Olympus photos:

First look.  10:40 pm MDT.

10:50 pm MDT

10:53 pm MDT

11:33 pm MDT

11:36 pm MDT

SAR arc over Snowshoe Mountain. 12:20 am (11 Oct).

A Stable Auroral Red (SAR) arc is the glow from neutral atomic oxygen atoms in the plasmapause (a region of the ionosphere hundreds of miles high) that interact with the global ring current (radiation belt).  This glow has a wavelength of 630 nm and is generally hard to see wtih the unaided eye (I couldn't see it, even though it is brilliant red in the camera).

As usual, click on an image to get into gallery view, from which you can access the full-size version.