WAITING FOR THE SHADOW

Total Solar Eclipse Exmouth 2023 - Joseph Cali

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The 2023 total solar eclipse was the third in a series of seven Australian continent total eclipses over 40 or so years. This was my 15th total eclipse. I have only been clouded out once, in Shanghaii mid-July 2009, in the middle of monsoon season. While I usually pay a lot of attention to the weather and relocation stategies, this eclipse was only visible on land in Australia, from the Cape Range National Park, the tip of the northwest Cape. As such, relocation options were non-existent.   Weather prospects were quite good. As such, I made a decision long beforehand to not worry about the weather.  I booked a tent site in a caravan park in Ningaloo during 2022.

      
Above Left: The eclipse path over the Cape Range National Park  Above Right: Paths of the 14 total, 3 annular and  some partial eclipses I have observed prior to the Exmouth eclipse, pins showing my observing locations at each event.

I left my home in the eastern states just after lunch on April 3rd.  I won't go into too many details here.

Eight days & 5250km of driving plus 4 rest/sightseeing days later I arrived in Exmouth on Saturday 15th April. On the map below, the blue numbers are the daily distances, the red numbers are the date of the night-time stopover.

In Australia, animals such as kangaroos, wallabies and emus can wipe out your car. Kangaroos and wallabies are mostly nocturnal so, I made a decision to keep the daily drive where possible to a relatively modest distances, average 500km per day and in daylight. 




The Bunda Cliffs at the top of the Great Australian Bight are a spectacular sightseeing spot located about a kilometre off the Eyre Highway roughly where the blue figure 490 appears near the WA border on the map above.


Bunda Cliffs in South Australia near the Western Australia border crossing

I had a rest day at the border where I caught up to my friends Phil and Margie Jones and Peter Fayle. We had a camp dinner together one night and then  went our separate ways. I drove through to Perth where I had a few days rest, food provisioning and staying at my friend's, Uta Bauer's place.  Colin's camera was waiting there at Uta's place.  I arrived in Exmouth without any incidents. Although I had my doubts about the 'food shortage' rumours in Exmouth, I did most of my shopping for food and supplies in Perth mainly so I could avoid crowded supermarkets in Exmouth. Rumours were also circulating that a minor COVID outbreak was occurring.


Coral Bay                       

View from the Vlamingh Head Lighthouse

Jurabi Turtle Nesting Beach Ningaloo                

Jurabi Turtle Nesting Beach Ningaloo

Submarine Communication Long Wave Radio Station

Charles Knife Canyon       


Preplanning and preparation:
Many months earlier, I made my rough imaging & observing plan:



This may appear to be very organised. However, my basic observing and photography plan has evolved gradually and only changes slightly from eclipse to eclipse so this was pretty easy to put together. What it does do, is give me an early basis for equipment preparation. Because this was a domestic eclipse and I was driving, I expanded it and brought heavier mountings and supports than the lightweigh kit I use whn flying overseas.

My usual overseas basic observing plan is to take one portable tracking device with one compact refractor or longer telephoto lens. Then I take one DSLR for some other stills on a tripod and one mirrorless with full frame fisheye for an ultra-wide video of the umbra. The refractor is fitted with a flip mirror with camera and parfocalised eyepiece. This means I can use the same instrument for viewing and photography. 

In this case with such a short totality and with the luxury of a large 4wd, I took two refractors mounted on a heavier mount (iEQ45) in a side-by-side configuration, one for photography and one for visual. I took another Losmandy tracker, my usual overseas tracking instrument, to track Colin Legg's camera.
In the days before departure, I also fitted my 4wd with a solar power system:-

•    160W roof solar panel
•    12V 120AH LiPO4 battery
•    Charge controller and distribution panel
•    60 litre car fridge on fridge slide
•    300W pure sine wave inverter
•    12v DC and 240v AC extension leads to deliver power to tent/telescopes etc.

This system gave me substantial space for perishable food plus ample power for charging and powering all USB, 12V DC, and 240V AC tech devices without worrying about access to power.

In addition to all the telescope and camera gear, I packed a tent, sleeping mat, sheets (for hot tropical nights), sleeping bag (for cooler nights), portable stove, food water, cooking gear, stove fuel, jerry can for spare fuel, snorkelling gear and clothes. Suddenly my large 4wd seemed very cramped.
I relaxed and did a few touristy things during those first days in Exmouth including a spectacular Whale Shark Dive on Ningaloo Reef.


I think that's me third in line. Photo taken by Sarita, dive company photographer.

More photo's of the whaleshark expedition here: -  https://www.facebook.com/media/set/?set=a.10218764644505568&type=3

After looking around, I decided to stay at the campsite. There were many factors that contributed to my decision: -

  1. I assumed that most people at the campsite would head to the beach or other locations so it would be nice and quiet.

  2. The sun being so high in the sky left few opportunities for a good wide field eclipse + landscape type images at the beach.

  3. I had a reasonable view from the southwest horizon to the eclipse – the passage path of the lunar umbra across the sky that I was trying to capture with the fisheye video.

  4. I had ready access to power from my 4wd and 240v outlets around the campsite.

  5. Trees provided good shade from the sun when not observing.

  6. Each evening, I observed flocks of corellas flying directly over my campsite and over the position of the total eclipse.
    By staying here, the birds might repeat this during the eclipse-wide-angle. Great for the video but might result in
    some lost closeups of the eclipse.

On Wednesday the 19th, the day before the eclipse, I set up the two equatorial mounts at the back of my campsite.

I used an inclinometer to set the elevation of the polar axes and my Google Earth method https://joe-cali.com/astronomy/articles/Google-Earth-Polar-Alignment/index.html
This enabled me to get the azimuth very close.

I then homed in to a more precise using the drift method for precise alignment first using the sun, then a star that evening. I set up and balanced the dual telescope arrangement on the iOptron iEQ45 and then Colin Legg's Canon 6D and Canon 70-200mm f2.8 L lens on my Losmandy Starlapse/Adventurer hybrid mount. The iOptron iEQ45 mount carried the two 80mm refractors, with the Orion ST80 fitted with a Denkmeier D21 eyepiece. These telescopes are much maligned, probably because the owners pair them with very low grade eyepieces. With a decent eyepiece and at a suitably low power suited to their fast f ratio achromat optics, they provide excellent sharp views in a lightweight (1kg) package and this is not the first time I've used one for visual observation of totality. The second refractor was an ED80 that I have owned for many years with a recently upgraded focuser.

I balanced both mounts. Colin's camera/70-200mm lens combo was a bit heavier than the dummy-load (camera & 300mm lens combo) I tested at home. Neither of us had wanted the counterweight cantilevered and bouncing at the end of the shaft so I left it up near the top and attached two heavy duty 3/8” x 12” tent pegs to the bottom of the counterweight shaft. As luck would have it, it balanced perfectly.

I powered up the drives from the 120AH LiPO4 battery in my 4wd and made sure they were tracking and that could point and track both mounts to the arc of the sky that the Sun would travel during the 3 hrs of eclipse without bumping into the mount or tripod or requiring a meridian flip. Everything checked out with no mount flips required until the eclipse finished at 13:05 local time.


That night, I did an extended drift alignment check just to make sure everything was working and tracking correctly. I quickly got both mounts very close between patches of cloud. The Losmandy-Starlapse/adventurer was tracking much better (no drift in Dec) than the iOptron which was drifting a little but small enough to work perfectly well.

The campsite was about 1km from the commercial centre of Exmouth. Our location had 54.5s of totality.

Coordinates:
2156'05.7"S       11407'39.4"E

Eclipse Day April 20th



In the photo above taken early eclipse morning, the 475B tripod on the left belongs to Phil Jones and is supporting his SkyWatcher Star Adventurer. No camera or lens yet. In the middle, my iOptron iEQ45 with both refractors already mounted. On the right, the Losmandy Starlapse is setup and awaiting Colin’s camera and lens. All three mounts were aligned the previous day. Later I set up two fixed tripods in the background. Jay and Benno Friendland also set up in the background. The trees casting shadows provided welcome shade in the morning while we were setting up. The Sun cleared the trees about an hour before first contact.



I woke, as I had every day since arriving in WA, at about 4am (6am east coast time). I paused to give some thought to my late parents. Today would have been my parents 66th wedding anniversary. I also paused to give some thoughts to my departed friend, and former eclipse chasing partner, Bengt Alfredsson. Today would have been his 20th total eclipse.

I had planned, tested, and documented my imaging strategy months earlier. On two DSLR's I would be using the Pentax Custom User modes that let you pre-select a wide range of exposure parameters.

Pre-programed Exposure Sequences

Pentax K5:

ISO 100
 
Rokinon 135mm ED f2 @ f 2.8

Autobracket:
1/500 s - s (equivalent)
@ 2eV intervals

Pentax K1:

ISO100

ED80 refractor 480mm f6

Autobracket:
1/8000s - 1/4s
 @ 2ev intervals

Pentax K-01:

Movie mode 30 fps -1 eV

Pentax 10-17mm f3.5 full frame fisheye
Lens set to 10mm (180 deg diagonally)



Thinking I was well ahead of the game, I stayed in bed and relaxed. I rose at about 6am and began checking and organising my cameras and other gear. Clouds were visible in the southeast, just as predicted by 3 weather models. All three models also predicted that those same clouds would stay and not move in over Exmouth. I mounted the optical and camera gear onto my equatorial mounts, checked camera clocks were synchronised and settings were set the same as the various protocols Colin and I had written up for the gear.

As always happens, people wandered by to chat, check out the equipment. Time passed all too quickly and first contact arrived too soon. Had I not done most of the set up and polar alignment the previous day, I would have been in trouble. Observing through the refractor, first contact seemed to occur right on time at 10:04:32. I was observing through my ST80 refractor and spotted it first. I didn't say anything to let the people using binoculars or naked eye, enjoy seeing it appear for themselves.

Leading up to and after first contact I struggled with the focus on my refractor. I later (after the eclipse) discovered that screws adjusting the tension on the Crayford focuser bearings had rattled loose during the 10 days on the road despite it having travelled in a padded carry case. As a result, I couldn't get the focus to stay, it would shift focus each time I locked the barrel. I struggled with this focus issue in vain, before first contact and during the partial phases.

With only about 20 minutes to totality, I decided to compromise on less than perfect focus and left it at that. I then quickly set up the video camera [Pentax K-01 mirrorless and 10mm full frame fisheye lens] and the wide corona imager [Pentax K5 APSc and Rokinon 135mm f2 lens. These were both very quick to set up and only needed to image totality. I already had the K5's custom user program mode set up with the exposure bracketing sequence and an intervalometer set to acquire the bracket set repeatedly to sequence the eclipse. I set the appropriate delay and left it to do it's thing unattended during the eclipse. About 5 minutes before totality, I started the video camera recording. The only remaining task was to remove the solar filters 30s before totality.

Tension was building, especially among the first-timers. My friends Phil and Margie Jones and Margie's twin brother Peter Fayle had travelled across the Nullarbor from Canberra and Melbourne to see their first eclipse. A large group of about 15, the extended family members of the Cross family(Clinton and Rosanne), were just metres away in the neighbouring campsite. Jay Friedland, whom I've known for 20 years, and his son Benno(10 years), were camping about 50 metres away but came to our campsite for the duration of the eclipse.  Jay always vocalises eclipses loudly and so he provided an excellent if somewhat excited narration on the video. I am always very quiet even when I want to narrate a video, I don't.
 
The video camera has a 180 degree corner to corner diagonal angle of view, about 140 degrees across the middle on the long axis. I pointed the camera and lens straight up, then tilted it down a little to the southeast so the  southeast horizon is on one side of the frame and the sun is on the opposite side of the frame. This camera was going to be recording the sweep of the moons shadow across the sky rather than details of the eclipsed sun.
I also set off the intervalometer on the Pentax K5 & 135mm ED lens about 5 minutes before totality. It's delay was set to begin the auto capture 22s before totality. I did snap a few manual test frames.

A few minutes before totality commenced, I went around checked all the gear one last time. I removed the lens cap and started the video recording-no filter. The Sun's image is quite distorted being on the edge of frame, the auto-aperture closes down & so no damage occurs.

A minute before totality I got ready and then moved through the gear removed the solar filters from the remaining cameras around the 30s mark before returning to my observing location at the eyepiece of one of the refractors. The K5/135mm combination began capture just seconds after I removed the filter.

On my ED80 refractor, my Pentax K1 camera has up to 5 custom programmable exposure modes. During longer eclipses, I use up to 4 of them. On this occasion, with just 54s of totality, and a longer focal length, I determined during preplanning, that I only needed and had time for two overlapping bracket sequences, one for the inner corona, diamond ring and prominences 1/8000s - 1/30s, and one for the mid-outer corona at mid totality 1/1000 s – s.

Refractor Capture Sequences:

Optic ED80 refractor
0.8x reducer flattener
480mm
f6

Pentax K1

Partial phases
ND5 f6
ISO 100
1/500 s

2nd Contact
Diamond ring
Baily’s Beads
Prominences Inner corona chromosphere
ƒ6 ISO 100
Program Mode: U1 x 2
1/8000 s
1/2000 s
1/500 s
1/125 s
1/30 s

Outer Corona
Program Mode: U2 x 2
1/1000 s
1/250 s
1/60 s
1/15 s
s

3rd Contact
Diamond ring
Baily’s Beads
Prominences Inner corona chromosphere
ƒ6 ISO 100
Program Mode: U1 x 2
1/8000 s
1/2000 s
1/500 s
1/125 s
1/30 s

The only thing I have to do while observing through the second telescope is to reach across and flick from U1 to U2 then back to U1 which after years of practice, I can do without even looking at the camera.

Outer Corona (135mm lens) Capture Sequences:
Pentax K5
Tripod
New filter + screw flange - Done
USER MODE 1
Outer corona only
5 step x 2eV bracket
135 f2
ISO100

1/4 s f5.6
1/2 s f4
1 s f2.8
2 s f2
4 s f2
K01
475B Tripod
Not required
Timelapse /movie capture

Totality 3 mins?

10mm full frame Fisheye  (90o x 140o)
from south east horizon
through zenith to totality
in the north east

Results
The Partial Phases

Because I had it set up and tracking well, and plenty of battery and memory card capacity, I captured this full partial phase sequence also seen at the head of this report.



Umbral Passage Video
Jay always vocalises eclipses and so he provided an excellent if somewhat excited narration on the video. I am usually very quiet even when I want to narrate. The video camera has a 180-degree corner to corner diagonal angle of view, about 140 degrees across the middle on the long axis. I pointed the camera and lens straight up, then tilted it down a little to the southeast so that the southeast horizon is on one side of the frame and the sun is on the opposite side of the frame. This recorded the sweep of the moons shadow across the sky rather than details of the eclipsed sun. Here is a link to the 720p HD video on my Vimeo page.
https://vimeo.com/826395876?share=copy

Or you can watch it at lower resolution here in the embedded window below:-



Inner Corona, Chromosphere, and Prominences (K1(14.6eV PDR) & ED80) Capture


ISO 100 f6 1/8000s - 1/4s

As already mentioned, I was unable to achieve critical sharp focus with the ED80 refractor. N
onetheless, I am reasonably happy with the final results despite the focus problem. Naturally, I'd
be happier with perfect focus but Murphy's law reigns supreme during solar eclipse events.

All cameras were set to lowest ISO to preserve maximum PDR(photographic dynamic range) ISO 100 f6 1/8000s - 1/4s


Single exposure PDR Capture but no PDR post processing.

Single exposure: PDR Capture and processing applied.

PDR Capture and processing of each of 3 exposures.   Three frames radially composited





Outer Coronal Streamers (Pentax K5, 10.6eV PDR, Rokinon 135mm f2 ED)

Pentax K5 ISO 100 Rokinon 135mm ED f2 Autobracket: 1/500 s - s @ f 2.8 (equivalent)

This little experiment was a bit of a gambit. I know the lens is very sharp so, I again set the camera to maximise PDR, on a tripod, with the intervalometer and autobracketing and starting exposure set in the USER Program Mode. The camera and tripod was well out of my reach and results were in the lap of the gods. The results with this setup have surpassed my expectations.










Ultra-Wide-Angle
The image below is a screen capture from the video with a still of the totally eclipsed Sun composited in over the top of the over-exposed image of the corona from the video.




Visual observations

Visual Observations were made by brief naked eye and most of the 54.5s totality with an ST80 refractor.  The ST80 refractor was fitted with a Denkmeier D21mm 65-degree apparent field eyepiece yielding 19x magnification and a 3.4 degree true field of view.

I was quite busy in the last couple of minutes leading up to 2nd contact. I did spot the approaching shadow but did not see if the umbral shadow could be discerned crossing the zenith to its rendezvous with the sun. A previously observed hybrid total eclipse, Nov 2013, had a 40km wide umbra the same as this one. Very thin high-level cloud filled the sky attenuating our view of totality but enhancing the visibility of the umbral passage. On this occasion, I was much more rushed and can't confirm observation of the passage.

My observations with the ST80 scope yielded some surprises. Five long coronal streamers extended radially out towards the edge of the 3.5-degree field. If you have never observed a total eclipse through an optical device, binoculars or small telescope, put it on the bucket list. The view, detail and silky luminosity is astounding.

The sight of half the lunar limb blazing with chromosphere was a sight to behold. Numerous prominences including one enormous vertical and one high suspended prominence. It was the blazing bright vertical prominence that really caught my attention. I thought I was imagining it, but the prominence appeared white to my eye rather than red. The eye doesn't work like a camera, you can't “overexpose and saturate to white.” Bright red looks bright red. This sight confused me, and I wondered if it was a prominence or not. It had to be and on very short exposure photos, it is red. After the eclipse, I wondered if my memory was playng tricks but then, one other experienced observer, Paul Haese, agreed with me and reported seeing it as white to the naked eye.






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