April 8th 2024 Total Solar Eclipse: Sungrazer Comet

Click to enlarge

Some news headlines leading up to the total solar eclipse last week suggested we might be able to see the "Devil Comet" (12P/Pons-Brooks) during totality, though with binoculars or a telescope, not naked-eye. We didn't see it but then we even forgot to use our binoculars to look at the eclipsed sun during totality much less remembered to use them to look for the comet.

I was asked whether the comet might appear in the photos I was taking with my telescope and my answer was, unfortunately no, it was well outside the field of view of my equipment. 

However, I was excited to see an article in my news feed late last night describing a comet passing close enough to the sun to fit in a telescopic field of view. Called SOHO-5008, it was a sungrazer, a comet passing so close to the Sun it would appear in coronagraph images by the SOHO solar satellite. This one had been identified in SOHO images the morning of the eclipse and several people found that they had captured it in their eclipse images. Later that day, it had burned up in the Sun. 

This morning, I pulled up my own images from totality and found that I had captured it, too! It took bumping up the exposure far more than I usually would but, once I did that and made a few other adjustments to bring out more detail, there it was. Here is an edit with labels similar to an image from my last post, noting some of the brighter stars visible from constellation Pisces and adding an enlarged inset for the comet. 

I may do another edit later on to balance out the overall image but i wanted to go ahead and share this now. 

Pretty cool, huh?

April 8th 2024 Total Solar Eclipse: Fine Detail in Corona

I went down a bit of a rabbit hole this week, assuming that to really get sharp detailed images of totality I needed to go through the rather involved process of using calibration frames to process all of the images I planned to stack before trying to stack, register and merge them. After spending a few evenings starting down that road, I took a break and in reviewing tutorials on processing solar eclipse images I ran across several that describe doing everything directly in Photoshop without the use of registration frames. 

Following the process described in this Sky & Telescope article, I created the image above using a set of images shot at 2 stop intervals from 1/4000th of a second to 1 second, all shot at f/5 and ISO 100 with my Nikon D750 through our Sky Watcher Evostar 72ED telescope. 

Click on it to enlarge and check out the incredible detail. You'll find features like:

• Plenty of detail in the solar corona
• Solar prominences
• The lunar surface illuminated with light reflected from Earth (Earthshine)
• Several stars from the constellation Pisces

This is just the first phase of edits described in the article so more to come. In the meantime, I did a separate version with features labeled. 

April 8th 2024 Total Solar Eclipse: Sun Funnel in Use

As described in a previous post, I assembled a Sun Funnel to use on our Parks 60mm refractor with the tracking motor running to keep the Sun in the field of view as it across the sky during the April 8th total solar eclipse. 

Our family members who gathered to watch the eclipse enjoyed having an alternative to staring at the Sun through eclipse glasses. It worked great! 

In this clip, you can see the partially eclipsed Sun, a sunspot and even clouds drifting by.

April 8th 2024 Total Solar Eclipse: Initial Telescopic Images

Fine details in the solar corona

One of my primary goals for this total solar eclipse was to capture a variety of telescopic views of the eclipse. The similar goal I had in 2017 was spoiled by overcast skies that resulted in a mad dash down the road with Beau Hartwig chasing clear skies. Seeing totality with my own eyes meant giving up on my photographic goal. I don't regret that for a minute but I was thrilled that this time the skies cleared for us just in time for the "Big Show". 

To avoid having to split my attention between experiencing totality and taking pictures, I used our old 2012 MacBook Pro running a software package called Solar Eclipse Maestro to control the camera, snapping pictures at pre-defined times and exposure settings. SEM worked flawlessly and had it not been for a user-error on my part (which I'll cover in a future post), I would have captured everything I planned for. As it is, I still was able to capture most of what I planned including:

• Diamond Ring effect (though not as spectacular as that from other people due to my snafu)
• Baily's Beads effect
• Solar corona fine detail
• Earthshine (lunar surface illuminated with light reflected from Earth)
• Partial phase images (though I missed much of the first half of the eclipse due to clouds)
• a full set of images and calibration frames I have submitted for the NASA-based science project called the Eclipse Megamovie

Although the images captured were as good or better than I hoped, post-processing them to fully bring out the available detail is a rather complicated thing involving a variety of software tools. I am still working on that but I wanted to go ahead and share some initial edits. 

The image above is a blend of each of the 19 different shutter speeds used to capture images to submit to the Eclipse Megamovie project. They were taken during totality to capture as much fine detail of the solar corona as possible. The project team will use the calibration frames to pull out even more detail than appears in this image but, for my first pass at this I used some basic stacking techniques in Photoshop. Click on it to see enlarged... isn't the level of detail incredible?

I'm also including some cursory edits I've done of a few other images below including a partial phase image and a picture of Baily's Beads. What I am the most excited about though is the spectacular solar prominences that appear in the Baily's Beads shot. Wow! Even more incredible is that the largest one was visible naked-eye. 

Once I've had time to go through the rest of my images and finish some of the more complicated editing processes, I'll share more of these. I'll also do a follow-up post on my equipment and what went into capturing these images. 

I hope you got a chance to see totality for yourself but, if not, please enjoy my first pass at sharing the view with you. 

Late in the partial phase of the eclipse. Note the sunspot in the center!

  

Baily's Beads and Solar Prominences

April 8th 2024 Total Solar Eclipse: Timelapse of Totality over Ellis County, Texas

UPDATE: Now that I've had time to work on some of my other images and videos, I went back and remixed this one to fix some things I rushed the first time around. In this edit the sky appears darker, closer to what we saw that day, so the coronal ring around the Sun stands out better. 

Another total solar eclipse imaging projects I planned to do is a timelapse sequence of the eclipse. In 2017 I tried shooting the entire eclipse but this time I just focused on the 5 minutes before totality, the 4+ minutes of totality and the 5 minutes after. Unlike 2017, we had much clearer skies and this came out pretty much just as I planned. Thanks to Alan Dyer (amazingsky.net) for the tips in his book on shooting the eclipse, specifically the tips on shooting a wide-angle timelapse!

To capture this, I set up my son Brian's Nikon D750 with our Irix 15mm f/2.4 wide-angle lens on a tripod at the corner of my son Chris' yard where we were observing the eclipse. My D750 was in use on the telescope so a big thanks to Brian for the use of his camera!

The sequence was shot with the internal intervalometer set to capture an image every second for 15 minutes with the timer set to start it at 1:35pm so that I didn't have to remember to start it on time. I set exposure ramping on so the camera would automatically adjust the exposure as the sky got darker and brighter, then set the exposure compensation to +1.33 so that it wouldn't be heavily overexposed during the pre- and post-totality shots. 

Once at home, I processed the 900 images in LRTimeLapse and Lightroom Classic to create a video clip from the images and then added titles, adjusted track speed and added music in DaVinci Resolve. This is the finished product! 

A few things to watch for in the video:

• At about the 18 second mark, look for the small star to lower right of the Sun. That's not a star, it is the planet Venus!
• The contrail at lower center is probably a commercial aircraft, possibly one of the one flying along the eclipse path to prolong how long they could watch totality. 
• At about the 36 second mark, the "insect" flittering about above us in the drone landing after shooting the arrival and departure of the lunar umbra. 

Enjoy!

April 8th 2024 Total Solar Eclipse: Preliminary Sensor Data

As I shared in an earlier post, one of the many projects I planned for the total solar eclipse involved doing data collection with a variety of sensors based on ESP32 microcontrollers. I haven't done any detailed analysis of the results yet but based on a quick review of some of the sensor data there are clear changes that are in line with what I expected. 

First up is the ambient air temperature measured with a BME280 sensor for temperature, relative humidity and air pressure. 

The air temperature certainly dropped which makes sense given the gradual and then sudden drop in UV sunlight. Interestingly, the drop lagged the eclipse by about 15 minutes with totality starting at 1:40pm local time and the lowest temperature being reached at about 1:55pm. The higher temperature in towards the end of the eclipse makes a little sense given before totality had been mostly cloudy and after totality was mostly clear. I am not yet sure what explains the dip at 2:55 or the temperature reaching over 110 at the end of the eclipse. It wasn't that hot where we were so I have some research to do. 

For air pressure, it appears there was a general trend down. Obviously, air pressure changes are related to broader atmospheric conditions. I suspect I needed to have data from a much longer period before and after the eclipse to have any chance of seeing any form of correlation.

As relative humidity generally has an inverse relationship to temperature (though it can be influenced by other factors), these results are what I would have expected. 

Next up is light level measurements. I used two sensors, an AS7341 color spectrum sensor and a TSL2591, a light level sensor. The AS7341 data will take more analysis to make sense of though it does show light levels in all frequencies it measures dropped to nearly zero during totality. The light levels in lux from the TSL2591 are pretty easy to understand. 

This completely aligns with totality which in the location in Ellis County, Texas, where we were started at 1:40pm and ended 4 minutes 16 seconds later. The left side of the graph makes sense as it was mostly overcast with the Sun occasionally poking through in the period prior to totality, hence the graph peaks and valleys before 1:40pm. The right side of the graph also makes sense. It was generally clear for about an hour after totality but with it turning partly cloudy again in the last half hour. Unlike the start of the eclipse, it was mostly clear skies with large clouds blocking the sun here and there. 

Although this is all very preliminary, just taking a glance at data results via the Home Assistant UI, these seem very much in line with changes expected during a total solar eclipse. If I find other meaningful results as I get time to do a more detailed analysis, particularly the sound level data and the color spectrum data, I'll post that, too. \

Click on a graph to see them enlarged. 

PS. 
As I expected, the magnetometer data collected with a QMC5883L doesn't appear to show any magnetic field changes that might correlate to the eclipse. I'll leave that science to the professionals!

April 8th 2024 Total Solar Eclipse: Lunar Umbra View from Drone

This is a aerial view of the arrival and departure of the Moon's shadow, the lunar umbra, over Ellis County Texas during the total solar eclipse on April 8th, 2024. 

We launched the drone just ahead of totality programmed to hover till the arrival of the lunar umbra and then orbit to film the horizon during totality. 

The sky got darker than I remembered from the 2017 total solar eclipse but the way things looked as the umbra arrived, growing darker first from one direction, and then as it departed, growing light first from the direction it had arrived, was the same as to 2017. 

Thankfully, we had relatively clear skies but the effect would have been similar even if it had been completely overcast. I had hoped that as the drone orbited it would capture the full 360 degree sunset effect along the horizon but it was too cloudy. You can get just a sense of it at the 58 second mark in the video. 

The total phase of the eclipse at this location was 4 minutes 16 seconds. However, as the focus for this video is on the visual experience of the sky getting dark with the arrival of the umbra and growing light again with its departure, the duration of totality is edited down to about 22 seconds. As the Sun was about 65 degrees above the horizon, it was not possible to include the eclipsed solar disk in this video. 

PS.

After posting this, I ran across a similar drone video from 2017 that doesn't show the lunar umbra arrival and departure but it does show the 360 degree sunset effect. Check it out here. 

Details:

Filmed from a DJI Mini 2 drone using DroneLink flightplan

Processed on Mac OS with DaVinci Resolve 

Music

"Eclipse"

by 1st Contact

Shared under Creative Commons License

Attribution-ShareAlike 4.0 International License

Data Collection Plan for Total Solar Eclipse 2024

First of all, if you've been watching the weather forecasts, you may have concluded that the total solar eclipse passing through Dallas on Monday will be a bust. Well, don't give up hope, yet. Even though we got clouded out in 2017 on our trip to Marshall, Missouri, as you would see in my post from back then, I still managed to capture of view of totality through the clouds. All it takes is for the clouds to part a bit at just the right time or the clouds to be high altitude and thin for us to still be able to see totality. Regardless of the forecast, be sure to get outside to see what there is to see!

Even if we are clouded out, you'll still experience one aspect of a total solar eclipse: it will get dark! With that in mind, I expect to have a successful day whether I get to see the total eclipse or not. I have a bunch of microcontrollers (ESP32) with sensors that I'll be using to collect data that day. 

That said, you may find that my approach to data collection is a bit unorthodox. Here's part of my setup for data collection. Yes, that is a Nonni's biscotti box. :-D

Seriously, here's the type of data I'll be collecting:

- light levels for visible light and near infrared (lux)

- light spectrum levels in various wavelengths

- environment: temperature, humidity, air pressure
- sound level changes (dB)

- magnetic field changes

WARNING: you may be a geek if you keep reading beyond this point. 

TL;DR

The architecture I'm using builds on infrastructure I already have in place. I use Home Assistant running on a Raspberry Pi for my home automation, control and historical data. Home Assistant supports integrating data sensors using microcontrollers called an ESP32 via a system called ESPHOME. By attaching various sensor components to an ESP32 then configuring it in ESPHOME, it makes it simple to automatically collect sensor data in Home Assistant for storage, retrieval, monitoring and analysis. 

Here is an example of a historical data graph in Home Assistant. The beauty of this besides being able to quickly visualize data is that Home Assistant also makes it easy to download the data for analysis in other tools. 

My original plan was to set things up to collect data through three full days, the day before, of and after the eclipse. Given the prospect of clouds and, more importantly, the forecast for rain on Tuesday, I've scaled back to just trying to collect data in the hours around the eclipse. I considered creating weatherproof enclosures for the sensors but that would have turned a shoestring-budget project into something quite a bit more expensive. 

After things have wrapped up, I'll pull up history for all the sensor devices in Home Assistant and download the data for further analysis.

As for the details of the sensors I'm planning to deploy, let's start with the light sensors. You can see details of the code plus the specific sensors in this gist on github.com. For this sensor package, the ESP32 and the sensors are mounted on a breadboard that is in the bottom of the biscotti box.

The reason is that my goal is to measure changes in ambient light. For various (and technical) reasons, direct sunlight would be more challenging to measure with these sensors. Given we should see a drop in ambient light levels (and color levels) during totality even if it is cloudy, I think the data will be more predictable and meaningful just measuring ambient light. Pointing the sensors straight up and blocking them from direct sunlight should accomplish this. 

One thing you'll see in the ESPHOME code for each sensor package is that they generally report data back to Home Assistant once a minute but include a switch I can turn on that tells the sensor to send measurements every second (or faster). I have Home Assistant automations set up to flip the high speed data collection switch on for each sensor package a little while before the eclipse starts and turn it back off a little while after the eclipse ends. That way once I set things up Sunday evening or Monday morning, I can focus my attention on the eclipse, leaving the data collection to happen automatically. 

On one side of the outside of the box is another ESP32 mounted on a breadboard with a sensor to measure the environment. Here's the gist with the ESPHOME including details on the sensor.  It will collect data on temperature, relative humidity and air pressure. The code also derives absolute humidity and dew point. 

Based on things I have read including published eclipse science projects, we should certainly see a change in temperature as the Moon's umbra passes over us during totality. Relative humidity has an inverse correlation to temperature so I expect to see changes to it that are similar to the temperature changes (but inverted). I have no idea what to expect in terms of changes in absolute humidity, air pressure and dew point but it will be interesting to see if there are changes that match the timing of the eclipse. 

On the other side of the box is an ESP32 with a digital microphone. This one is set up to measure changes in sound levels throughout the eclipse. You'll see in the gist, this is based on a custom ESPHOME component. It provides sound levels in several forms but my interest is in just having the unfiltered (raw) sound levels. 

Measuring changes in sound levels that can correlate to the total phase of the eclipse may be challenging. Although it may "get quiet" in terms of reactions to the darkness by birds and insects, my guess is that loud expressions of joy during totality by folks gathered with us to observe the eclipse may offset any drop in sound levels by nature. 

The last sensor package I've put together was an afterthought. I had one more ESP32 and also had a sensor that is a magnetometer, one that measures changes in magnetic fields in 3 axis. See this gist for the ESPHOME code which includes details of the sensor. The ESP32 I'm using in this case also happens to be much smaller than the others which seemed like to a good idea for a sensor trying to measure changes in local magnetic fields. 

Based on my research, there have been changes in magnetic fields around Earth measured during past total eclipses but those measurements were performed with sophisticated equipment in the upper reaches of the atmosphere or in space. I don't have any reason to expect that I'll measure any changes that correlate to the timing of the eclipse with my simple magnetometer setup but I figure I'll do the data collection and see what happens. 

For this sensor package, I've mounted the sensor on top of a wooden yardstick with the ESP32 below and a Wi-Fi antenna below that. My plan is to have this mounted on a stake well away from structures and people to minimize other magnetic fields nearby. However, that means it's further to the Wi-Fi router, hence the extra antenna. I'm also using a power pack instead of using a power adapter plugged into AC power. This means the only limitation on where I can put this will be how far from the house I get before the Wi-Fi signal drops. 

Sometime next week when I have had time to review and analyze the data collected on Monday, I'll write up my conclusions and share them here. 

Just two days and a wake-up before show-time!

Stay tuned!