Version 2 of Solar Eclipse Timer worked great in South America for the 2019 Total Solar Eclipse! I have had great reports from Chile and Argentina!
The English version and the Spanish version were both used successfully!
I played the app through a Bluetooth speaker at my observing position so the group we were observing with could follow the progress of the eclipse.
We had perfectly clear skies and a very mild temperature with no wind on eclipse day.
It was beautiful to see the eclipse set into the mountains. The spacing between the images in this composite was determined by the Partial Phase Image Sequence Calculator (PPISC) in the app which does the clock time calculations. This is the unaltered progression along the ecliptic. The camera and the camera tripod were fixed in position. The only processing that was done was making the totality layer lighter so the mountains would show as a silhouette.
I do not use an intervalometer for the spacing of the partial phase images because the time between C1 and C2 is very different than the time between C3 and C4 in a setting eclipse such as this one.
The PPISC in Solar Eclipse Timer does the math and delivers these times you need to take your images. The times are calculated exactly for your position on the path.
This is a cropped and stacked image of the sequence of Baily's Beads going into 2nd contact.
This is a cropped and stacked image of the sequence of Baily's Beads coming out of 3rd contact.
The inset image is the full solar disk through a filter at 2 minutes after first contact. There were no sunspots on eclipse day. It's unfortunate because sunspots can be used to help focus on the Sun. When there are no sunspots you must focus on the limb of the Sun and this can be challenging and less accurate. But the highly cropped image of the limb of the Sun just prior to 3rd contact shows that good focus was obtained as this images shows beautiful prominences and chromosphere.
This is an unprocessed image of totality. This was taken with a shutter speed of 1/6 second with an ISO setting of 200. The telescope was working at f10 with a focal length of 905mm. High Dynamic Range image processing will be coming.
Temperature Data Log: Our observing site witnessed an amazing decrease in temperature of 26 degrees Fahrenheit. There are some reasons for this observation.
Season: This is a winter eclipse in South America. This eclipse was 11 days after the winter solstice, so the Sun is on a low ecliptic in the sky.
Time of Day: This was a late afternoon eclipse with C1 being at 4:25 PM and Max eclipse at 5:40 PM and C4 being at 6:46 PM, but sunset was actually a few minutes prior to C4. So there was a lot of time for the ground to cool
Observation Site: Our ground cover was medium brown colored dirt. There was no grass and no surrounding foliage.
Local Meteorology: There was basically no humidity, this plateau is relatively far from the base of the Andes and was really dry. When we arrived to the site the was no local wind currents at all, it was almost perfectly still. However, during the partial phases we did noticed that a light breeze occurred. I believe we had the perfect calm conditions to witness an "eclipse breeze" that is described by some eclipse chasers. This breeze is thought to be due to the deepening partial eclipse and the decrease in energy to the ground resulting in the cooling of the air close to the ground. But above the ground the air is still warm in an "inversion layer". These pressure gradiants eventually cause the air to move and mix and create a light breeze. At our site we felt the breeze. And becasue we had perfectly calm conditions otherwise, the temperature logger showing bumps upward in the temperature, is thought to be due to the mixing of the warmer air in the inversion layer getting moved to the ground in an "eclipse breeze" and recorded. This is an interesting way to indirectly find evidence of the mysterious "eclipse breeze!"
Ambient Light LUX Data During the Eclipse: This is the change in LUX at the observing site. The data was obtained with a simple Pasco Scientific ambient lighting data logger facing obliquely downward towards the ground at the observing area where I was set up.
What is amazing is how well our eye-brain system compensates for this very slow progressive decrease. It doesn't actually look dimmer until inside of 5 minutes before C2. Amazing!
You beging to see the Purkinje Effect color changes about 5 minutes before totality.
Ambient Light Color Spectrum Data: The data on eclipse day showed something interesting that I did not expect. The color spectrum reaching the Earth was flat and steady from 1st contact all the way up to 2 minutes before 2nd contact and then it changed dramatically and rapidly The limb of the Sun DOES emit an altered color spectrum to Earth in the path of the eclipse, but it changes abruptly when you get to the point of a 2 minute crescent or less. The relative percentage of the blue and green spectrum goes down, just as we are a point of low ambient light where our rods, that absorb these colors, are starting to function. The relative percentage of the red spectrum increases, but this is at a point where the low ambient light does not allow our red sensitive cones in the retina to work effectively. So our perception of the lighting at this point in the eclipse is extremely complex and complicated by the changes in the spectrum of light reaching our observing position. This is the weirdest 2 minutes of natural lighting that you can ever experience!
This spectrum shift would certainly have an effect on the way we perceive our surroundings, if we had the chance to concentrate on it and enjoy it. One issue about appreciating this lighting change during an eclipse is the fact that the last two minutes before totality is a very exciting time! This is the prime time to look for shadowbands on the ground and for me that always takes my attention away from doing anything else. In addition, people are anticipating and preparing for totality. So the last 2 minutes is a very difficult period of time to concentrate on the color tones of your surroundings and the overall intensity of the ambient light continues to decrease. That is why you should try to appreciate the Purkinje Effect between 5 minutes and 2 minutes before 2nd contact.
Partial Phase For A Setting Eclipse: An eclipse that occurs just before sunset is challenging because the duration of time between C1 and C2 is going to be much different that the duration of time between C3 and C4. For this eclipse at my observing position the second set of partial phase progressed 9 minutes and 10 seconds faster. This requires adjusting the duration of time that passes in between the crescent pahse images if you want the percentage of crescent phase visible to be the same for the ten images before and after totality. Prior to my app whichwas released in 2017 I used to calculate the clock times manually. Now I use PPISC in the app and it worked perfectly in 2019 even though C4 was obscured by the mountains.
Partial Phase Image Sequence Calculator Times For 2019 (PPISC): This is how the clock times for PPISC are presented in the app. It shows the four main contact times and then the 10 clock times needed before totality and the 10 clock times needed after totality. Take an image at these times and you will get a perfect sequence.
Eclipse Breeze Theory: Energy from the Sun heats the ground which heats the air above the ground, which then rises even further above the ground by the process of convection. During an eclipse the energy delivered to the ground progressively decreases and this is seen as a decrease in the ambient tempeature at the ground level. But the air above this lowest level at the ground does not cool as quickly so there is a layer of warmer air called an "inversion layer." As more eclipse cooling occurs pressure gradients get created that make the air begin to move. This is thought to be the reason for the mysterious eclipse breeze. Of course this is extremely rare to witness because the conditions on eclipse day have to be completely free of wind or breezes caused by normal meteorology. We were fortunate enough to have those perfect conditions at our eclipse observing position for the 2019 eclipse and I truly believe we witnessed an "eclipse breeze!"
Eclipse Breeze Theory: As the temperature at the ground level gets progressively cooler and the height of the coolness gets higher the stability of the layers decreases due to pressure gradients. These gradients cause air to start to move and circulate and this is thought to create the very light eclipse breeze felt on the ground. There are some studies that have recorded changes in wind speed with an anemometer. There has also been some documentation of changes in wind direction. But it is always difficult to factor out regular wind or breezes coming from standard atmospheric meteorology conditions.
At our site we had the benefit of an afternoon with absolutely no standard atmospheric wind. The fact that the temperature data has upward bumps in temperature is indirect evdidence that there was mixing of the inversion layer and that mixed air was warmer and carried down to the ground where it was measured by my temperature logger. Very interesting and very exciting to have experienced this partial phase phenomena!
Sharp and Fuzzy Shadow Experiment: In 2019 I reproduced the sharp and fuzzy shadow experiemental model that I first introduced in 2017.
I made improvemets to the model which included; 1. thinner bars creating the shadows to decrease edge difraction effects. 2. keeping the background in the same plane as the progression of the eclipse to decrease shadow angles. 3. mounting a camera within the experiment to take images throughout the first set of partial phases with the exact alignment and field of view.
The 2019 model worked perfectly and confirmed the results form 2017.
Shadows created from the bars that are in-line with the crescent phases have sharp edges. Shadows created from the bars that are perpendicular with the crescent phases have fuzzy edges. The concept being that the crescent phases actually send light rays to Earth that are more linear. So the bars that are perpendicular to the crescent still behave as if the Sun were emitting an extended source of light, the bars that are in-line with the crescent behave with the Sun emitting a linear source of light.
The effect began to be visible just after the 50% crescent phase.
It's amazing that the shape of the Sun 94 million miles away can affect the way shadows are cast on the Earth!!
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