OASI: eclipse

The track of totality of the eclipse of 08 April 2024 crossed continental North America from Mazatlan on the coast of Mexico to New Brunswick. Umbral contact times (UT) were as follows (from the BAA Handbook for 2024):

Paul Whiting, FRAS, Valley Mills, Waco, Texas

For once, the journey to the airport hotel went smoothly. Even the notoriously unreliable Heathrow Hotel Hoppa operated to schedule. Following an early start on the day of our flight, the journey to the airport terminal was also uneventful. The flights to Dallas/Fort Worth and on to San Antonio also went well. I even managed to choose a happy US border guard, who asked sensible questions about the eclipse. One interesting security announcement came over the tannoy at San Antonio airport: "Passengers please note that hand guns must be stowed in hold luggage and not carried on to the plane"!

Blue Moon beer

The Alamo

Stargazer

Welcome

We had two days spare in San Antonio to explore the city. We went sightseeing to The Alamo, where Davy Crockett found fame, and took in a modern statue, The Stargazer, very appropriate to our journey. San Antonio turned out to be remarkable. I expected a dusty old "frontier" town, but instead found a smart, tourist-friendly community built around the San Antonio River and the drainage canals added following a disastrous flood in 1921. The area was dolled up as the "Riverside Walk", with many tourist pubs and restaurants, including the Mad Dogs British Pub; although the pub housed a red telephone box, alas its supplies of London Pride, Sam Smith’s and any other remotely British beer were exhausted! So, I drank mango wheat beer, a delicacy I discovered in Australia for the hybrid eclipse of 20 April 2023. Otherwise, the beer of choice was Blue Moon, a Belgian beer very popular in the US. I first saw it in Wyoming while on a trip to observe the eclipse of 21 August 2017 and, of course, it is very apt for the occasion... While eating lunch one day in the Crab Shack, we were treated to an interesting "cabaret show". An itinerant was arguing and swearing loudly and the police were called. It was all handled very professionally with minimal disturbance to the other guests.

Texan food portions, in general, were enormous. We learned not to order a starter and a main course, unless we wanted a couple of meals to take home in a doggy bag! Prices, however, after adding tax and the ubiquitous tip, were every bit as big as the portions. The going rate for tips is now 20%; the largest we saw "suggested" on a bill was 26%.

At the end of Day 2 in San Antonio, we attended the Eclipse Briefing. At this time, the weather forecast for the day of the eclipse was not good, essentially thunderstorms all day. However, various meteorological agencies appeared to employ diverging models and there was no agreement as to which areas would be under cloud cover during the eclipse.

The next day, after a three-hour coach journey to Waco, we found the weather clear and sunny, but the forecast for the following day, the day of the eclipse, was still very uncertain. Our hotel in Waco, although a little more comfortable than the one in San Antonio, had strange ideas about customer service. If staff didn’t have what you ordered, they simply brought you what they had, placing it in front of you without a word about the substitution! Thus, the breakfast waitress made a big point of pushing three special eclipse cocktails, even finding out for us what was in each of them. One sounded great: a dark rum punch with grenadine and orange juice. So later that day we ordered two. A while later two drinks were served: tequila-based with lemon juice and added salt and cayenne pepper. When we pointed out the error, the waiter explained that none of the ingredients to mix the special cocktails had been available. I thought of Fawlty Towers...

The next morning, eclipse day, dawned with thick cloud. We had been issued with breakfast vouchers to present at breakfast. The buffet breakfast was good, but when presented with the bill, the waiter said that the vouchers covered everything except the tip! Basil Fawlty again.

Anticipating major traffic snarl-ups, we set off very early to the Equestrian Centre in the area of Valley Mills, just outside Waco, a little nearer to the centre eclipse line. Of course there was hardly any other traffic! The cloud was reasonably broken when we arrived. The site was well laid out: there were approximately 150 obervers and we had several acres dedicated to our exclusive use. There were portaloos and a stall selling food and drink and T-shirts.

The owners of the site toured round on horseback, carrying a US flag, greeting the visitors. They interviewed people, presumably for social media, to promote the riding school. I volunteered to be interviewed, speaking my responses to the microphone on the tip of the flag pole! Questions included "How do you pronounce..." several Spanish and Mexican place names containing many Qs and Xs. They also asked me to pronounce "Worcestershire" and "rural". Finally, they asked me to taste some Cheetos (similar to cheesy Wotsits), both cheese and mega-spicy varieties. When I asked When does the spice kick-in?, they were taken aback. I didn’t tell them I had a cold and had lost much of my senses of taste and smell! An odd question was "What does 'yonder' mean to you?" I responded that back home it would be the next field, but as everything was bigger in Texas, it would be over the horizon!

After the interview, time was approaching second contact, C2, when the eclipse becomes interesting. There were vast tracts of clear blue sky interspersed with huge thunder clouds. However, as a tame meteorologist explained, the reduced heat from the Sun undergoing eclipse prevented the formation of thermal convection clouds; so, in a way, the eclipse cleared the clouds for us.

The eclipse was visible from just before C2 all the way to third contact, C3, and beyond without interruption from cloud.

Visually, the eclipse was one of the nicest I have seen, with a marvellous naked eye prominence visible throughout most of totality, and a narrow corona, as expected at solar maximum. Despite the sky being dark, the only celestial object visible other than the Moon was Jupiter. Many people used the four-minute window of totality to search for comet 12P/Pons-Brooks, with little success. The horizon shadow effects were fantastic. The photos below show progression of the eclipse from C2 through mid-eclipse to C3.I experienced some problems focussing the camera correctly so, unfortunately, the photos below are not mine.

Throughout the eclipse, I took the usual measurements of vertical light level and temperature in the shade, charted below. Both charts show clearly the effect of the variable cloud cover between C1 and C2.

Temperature

Light Intensity

Following the eclipse, we returned by coach to Waco, only to enjoy a thunderstorm. The next day, there was torrential rain for most of the return journey to San Antonio. Luckily the rain stopped when we arrived. We reached our hotel at 2.00pm, two hours early, to be informed that our hotel rooms would not be ready until 6.00pm, two hours late. The hotel let us leave our cases in the conference room, while we went back along the River Walk to our favourite Mexican bar. We aimed to return to the hotel at 4.00pm as we had been offered free drinks in the Gavel Bar for the duration of the two hours delay; the hotel also laid on a substantial free buffet. And the staff didn’t even ask for a tip!

The day dawned to return to the UK. We had a 45 minute turn-around in Dallas. Storms at Dallas delayed our arrival, but we were informed that the London flight would also be delayed. It was, but not quite long enough for us to catch it! We were re-booked on a flight four hours later, but we were assigned the last two seats, economy class. We had paid for business class seats, so we went to the business class lounge to pass the four hours. The lounge gatekeeper looked concerned when I told her our story but I thought that as we had been downgraded, she wasn’t going to let us anywhere near the free champagne. However, not only did she let us in, she found a business class seat for Diana. I asked that Diana occasionally send a glass of champagne back to me in economy. The gatekeeper did tell me to "trust her" and, about 40 minutes later, I was summoned to the lounge ticketing desk to be "re-ticketed" with a business class seat next to Diana. Shame in a way, I did fancy the idea of receiving a glass of champagne "from the lady in business class"!

On the journey to the UK, I lost my wristwatch and a call went out for any medical personnel on the flight, but apart from that it was uneventful. The delay of four hours meant that my timed advanced rail ticket was useless. Worse, there was a mysterious bleep that seemed to follow me on the Elizabeth Line, again at Liverpool Street Station and then on the train from London to Ipswich. I checked my bags but the sound didn’t appear to emanate from them. A fellow passenger was being driven to distraction by the noise so she helped me move luggage around to try to locate the source of the bleep. However, when I alighted at Ipswich, the bleeps stopped and, despite a thorough search, I could find no possible cause. The mystery remains unresolved...

So, despite all odds, it was another successful eclipse. Comparing the graph of vertical light intensity to that of the eclipse of 20 April 2023, it can be seen clearly that the 2024 eclipse was the darker of the two at totality (1.98 kLux compared to 23.38 kLux). The peak darkness level may well become the prime area of research for the next few eclipses.

Nigel Evans, Universidad Automona de Chapingo, outside Torreón, Mexico

Most eclipse-chasers set off for either Mexico or Texas where the probability of seeing the event was highest. We elected to travel with Astro-trails to the Universidad Automona de Chapingo outside Torreón in Mexico, where the eclipse would be of duration 4m 27s at an altitude of 70°. We flew from Mexico City to Monterrey, then took a three-and-a-half-hours coach journey to Torreón itself, arriving the night before the eclipse.

Cameras

Camera 1, the prime instrument, was a Canon 50D with 500 mm lens. This would take photos of the chromosphere around C2 and C3, and a selection of exposures during totality to record the corona. Prior to leaving for Mexico I had assigned a Canon 60Da for this task; one day, during tests, it failed fatally. It is a good job that this happened when it did then and not during the eclipse…

Comet 12/P Pons-Brooks would be some 25° from the Sun. It was not expected to be visible to the naked eye but would be recorded in stacked images taken during totality, so I dedicated Camera 2 to record it. Cameras 1 and 2 shared a driven mount and were both controlled from a laptop.

Camera 3, again on a driven mount, was set to record the flash spectrum. Here the recording would be in video mode.

Camera 4 was set to record shadow bands crossing the landscape. I have seen them only once before, at the eclipse of 29 March 2006.

Cameras 5 and 6 were GoPro models to capture wide-angle views of the event: Camera 5 was equipped with a standard lens and Camera 6 a fish-eye variant to capture the majority of the sky. Cameras 3, 4, 5 and 6 would be started some 10 minutes before C2.

Eclipse Day!

We were due to leave our hotel for the observing site at 8.00am (local time), with the journey expected to take about an hour. C1 was just after 11.00am. First problem: no coaches! This is Mexico. Our coaches never arrived as someone else, somewhere had use of them… Oh, problem solved… the coaches that had brought us from the airport were available and were pressed into service, some 60 minutes behind schedule. We arrived at the observing site at about 10.00am, to find a soccer field full of our eclipse-chasing mates from other hotels, all set up. Or not.

Second problem: it was overcast. Before a total eclipse, the Sun has two vital functions to perform: first to act as a focus target for all the expensive imaging equipment and second to provide a signpost towards north to enable alignment of driven mounts. When it's overcast, neither function is possible!

For focussing, I pressed into service the rather low-contrast view of the distant horizon. Mr Compass came to the rescue for the (approximate) alignment of the driven mounts. The only redeeming feature of the clouds was that they stopped us from being boiled alived: in recent days it had typically been 28°C, exceedingly dry, dusty and windless but on eclipse day it was more like 15°C.

C1 came and went, invisible behind the cloud. With 30 minutes to go to C2, we saw the Sun – briefly. At about 10 minutes before C2 we could see darkness in one corner of the sky and I switched on the four video cameras, more in hope than expectation. At this time I realised that I had not focussed the flash spectrum camera. Normally I would focus it on the Sun with a solar filter in place - here the clouds were so thick that I was able to focus directly (via an electrical viewfinder).

With less than a minute to C2, the filters came off and equipment started to click and purr. A cheer went up as the shadow of the Moon reached us and we caught our first glimpse of the corona, albeit through some quite thick clouds. But one of my computer-driven cameras (it turned out to be Camera 1) was not purring. It was not obvious what was wrong so I followed the first rule of eclipse photography: don’t try to fix anything during totality; just abandon it and watch the event!

Apart from the eclipsed Sun, Venus and Jupiter should have been easily visible in the sky, with Mars and Saturn a bit harder to find. But not even Venus was visible! I looked around at the colours of the horizon and in the latter minutes watched the development of a lovely pink prominence at the 5 o’clock position on the solar disk, following the Sun with binoculars all the way to C3 – and another round of cheering.

After C3 the skies became clearer. I restarted Camera 1 to record the outgoing partial phases then disassembled the mounts whose work was done. By fourth contact, C4, standing out in the Sun was pretty unpleasant.

As I trudged back to the bus, I started to suffer a bit – was it dehydration, sunstroke or just exhaustion in the heat? At 2:00am the following morning, the answer came when I had to hurry to the bathroom…

Post Mortem

Most of my efforts at photography were thwarted by the presence of cloud. In addition, for reasons unknown, Camera 1 lost contact with the laptop about 10 minutes before totality. Camera 2 dutifully photographed the same piece of sky again and again, hoping to catch the comet. It failed to catch the comet, but did occasionally capture Jupiter, some 6 magnitudes brighter. Cameras 3 and 4 worked, but conditions rendered worthless their images of the flash spectrum and shadow bands. Cameras 5 and 6 recorded memorable footage of such a cloudy event, even revealing a tiny white doughnut (the eclipsed Sun!) in the sky.

Many others in the group have their own tales of woe: cameras that recorded nothing useful, or caught out-of-focus views. However, some observers did capture very impressive images during fleeting gaps in the clouds. But the main thing is that we saw the eclipse.

Below are still images taken around mid-totality and videos (at 10x live rate) spanning from before C2 until after C3.

Camera 5

Camera 6

Neil Short, Tiffin, Ohio

I once again visited the USA on a mission to see a solar total eclipse. As with the total eclipse of 21 August 2017, which I observed from from Payette, Idaho, the path of totality once more passed over the location of a member of my wife’s family, this time her cousin Eric in Tiffin, Ohio. Tiffin is a small town, population around 18,000, in the northwest of the state.

That’s the good news. The not so good news was that the probability of enjoying a clear sky in Tiffin in early April was at best around 50%.

On the day of the eclipse, the early morning sky was largely blue and free of cloud, offering great promise. Eric, our good friend Jim from "nearby" Cincinnati plus Katherine and I settled down on chairs on Eric’s driveway (not one of the great backdrops to an eclipse!) to enjoy the spectacle. Event times were predicted as follows (approximate, local times): C1 at 14:00, C2 at 15:12, C3 at 15:16 and C4 at 16:30. However, with a forecast of showers later in the day, cloud levels increased through the morning, causing increasing concern.

Fortunately, thick cloud did not appear, the light became monochrome, the birds fell silent, the occasional dog barked and, with the high, thin, wispy cloud present, the moment arrived…

Totality is a tremendous event and gloriously moving. We enjoyed 3 m 52 s of totality so I could take photos and also still find time to look at the eclipse. All too soon, totality was over. We could all relax and enjoy the end of another wonderful day.

The following day we bought the requisite T-shirts for the event before it was time to move on to Chicago and then to Hawaii with the promise of another couple of sites of astronomical interest…

In the driveway.

Approaching C2.

Eclipse T-shirts.