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.

Prelude to the aurora

Note: aurora images from the next night (Tuesday) are in the previous post.

Monday night, 07 October, was clear, but the sky was again not very dark for Creede, with sqml=21.05–21.1.  I hate to waste a clear night, so my intention was simple: take one shot of the southern sky featuring Saturn, and then pack it in.  Here is that view of the southern sky:

Sony A7iii + 20mm FE f/1.8 G lens + Hoya Softon filter.

Nothing remarkable there.  Saturn is featured (the bright star just right of center) and some faint green airglow is evident near the horizon.  A full-size crop of the central region shows both Saturn and Neptune:

Mission accomplished.  Then out of habit I turned around and took what I thought would be a parting shot of the northern sky.  Wow!

Sony A7iii + 20mm FE f/1.8 G lens.  No filter. 10:41 pm MDT.

That broad red band arching up from right to left is called a Stable Auroral Red (SAR) arc.  This phenomenon is not actually auroral.  It is a misnomer dating back to the discovery in 1956, before the excitation mechanism was understood. It is caused by heat exchange between the ionosphere and Earth's ring current system (Van Allen radiation belts)  The diffuse red glow near the northern horizon, however, is auroral (i.e., caused by high-energy charged particles from the sun).

One important aspect of this image is that neither of these two features was visible to the unaided eye.   However, a long camera exposure (30 seconds in this case) easily picks up the red glow. 

Here is a more northerly view:

Same camera and lens.  Softon filter.

The SAR arc can be seen passing through Perseus and just over the top of the Little Dipper.  Polaris is the star that is just left of center.

SAR arc high in the northern sky.

After processing these images I decided to head back out with a wider-angle lens, and obtained the auroral images featured in the previous post.

Aurora over Creede!

 Last night (07 Oct) I was outside at 10:30 pm photographing the night sky with a Sony A7iii camera and a Sony FE 20mm f/1.8 lens.  The sky was not particularly dark (sqml=21.05) and the camera was picking up strong red color in the northern sky.  The color was not visible to the unaided eye, but was quite spectacular in the 30 s camera exposures.

After processing this first set of images, I returned an hour later with a wider-angle setup: Olympus E-M1iii camera + Laowa 7.5mm f/2 lens.  Now, however, as I was framing the first image I realized that I could see the red glow.  And it was getting brighter!  For the next 10 to 15 minutes the northern lights put on a good show easily visible to the unaided eye.  A curtain of red with green spikes shimmered over Creede and the La Garita mountains.  Just as I decided this was worth waking up the neighbors for them to see, the northern lights faded back into invisibility.  Show over.

11:23 pm MDT.  Laowa 7.5mm f/2, no filter.

In this image there are two separate phenomena visible:  the auroral curtain over Creede, and higher up in the sky a much fainter red band called a SAR (Stable Auroral Red) arc.

11:26 pm MDT.  Laowa 7.5mm f/2 with Hoya Softon filter.

11:29 pm MDT.  Laowa 7.5mm f/2, softon filter.

11:31 pm MDT.

In the next post I will show some of the earlier photos when all of this was still invisible to the unaided eye.

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