Mathematicians and scientists have used solar eclipses to study the solar system, and more specifically the sun itself, for thousands of years. As The New York Times article, The Illuminating Power of Eclipses, explained, “With the sun obscured, eclipses can be revelatory: Starting at least over 2,000 years ago, they have been fodder for significant discoveries.”

These studies have led to the discovery of helium, the universe’s second most common element, proved (and then disproved) the existence of the planet Vulcan, and even verified Einstein’s theory of general relativity. As the centuries marched on, many of these discoveries were made possible by improvements in the apparatuses used to observe and record data from the eclipses.

This week’s eclipse, combined with advanced technology and computing power, will result in a unique scientific asset that could ultimately outshine all previous discoveries. Enter Citizen CATE.

To make the most of this week’s event, the National Solar Observatory (NSO) created the Citizen CATE (Continental-America Telescopic Eclipse) Experiment. CATE volunteers were banded together into 68 groups that spread out across the path of totality to record the eclipse. The goal of CATE was to produce a scientifically unique data set: high-resolution, rapid cadence white light images of the inner corona for the entire 90 minutes of the eclipse.

According to the CATE website, “The real strength of the CATE data is that for the first time it will reveal a time sequence of coronal continuum intensity at relatively high spatial and temporal resolution for 90 minutes duration. Time variable phenomenon studied in the corona using narrow-band images which probe particular temperature regimes will now be visible using white light images which probe all temperatures of the corona. Because total solar eclipses last only a few minutes at each location, these types of studies are impossible unless data from several eclipse locations are combined.”

When complete, the combined data from the sites will give scientists a higher resolution map of the plumes’ locations. Scientists also hope to measure movement within the plumes using the extended observation session. The images from the Citizen CATE sites should increase understanding of the corona’s internal movements.

Solar plumes are thought to be the origin of high-speed solar wind. Large solar plumes have the potential to interfere with the Earth’s power grids, GPS and satellite systems. In 1989, a massive solar plume knocked out power grids across North America, creating an outage that affected millions of people.

Capturing the Sun

To combine the data from various eclipse locations, each of the 68 groups used identical equipment. This was critical to ensure the data from each site could be combined into a single video. The equipment included an 80-mm refractor telescope from DayStar filters, a motorized mount and drive system from Celestron that tracked the movement of the eclipse, and a 5.0 MP Mono USB3 Vision camera. Each team also was given a laptop that ran an application written in MATLAB to control the camera and capture the images during the eclipse.

A live image histogram, calculated with the imhist function in Image Processing Toolbox, provided visual feedback for optimizing the exposure time.

Each group captured 1,000 images of the eclipse as it traveled through their area. The teams then used MATLAB to create a high-dynamic range (HDR) image from each multiple exposure cycle. These images will be combined to create the 90-minute video of the eclipse.

This HDR image was obtained from combining a cycle of 8 multiple exposure images.

So far, 56 teams have provided data while five of the 68 sites were obscured by cloud cover. The remaining seven sites have not yet submitted data. Below is some of the video that has already been created.

Once the team processes the video from all the teams, the full video will be available on the NSO site. Check back to see the video. I’ll post the link as soon as it’s available.

Eclipse facts

• The last total solar eclipse that traveled across the entire U.S: June 8, 1918. The eclipse started on the west coast at 10:16 AM. It crossed to the Atlantic Ocean at 2:46 PM.
• The next total eclipse that will travel across the U.S.: April 8, 2024
• The eclipse glasses you worked so hard to get won’t expire by then, per NASA!
• If you don’t want to keep your glasses until then, you can donate the glasses to Astronomers Without Borders so that children in South America and Asia can safely watch the next eclipses in 2019.

For more on how the citizen scientists worked with the Citizen CATE program, check out these blog posts:

1. MATLAB and the 2017 Eclipse – Part 1: The Citizen CATE Experiment
2. MATLAB and the 2017 Eclipse – Part 2: Training the Volunteers
3. MATLAB and the 2017 Eclipse – Part 3: Rehearsing for the Eclipse
4. MATLAB and the 2017 Eclipse – Part 4: Imaging the Eclipse