On August 21, 2017 a solar eclipse occurred over
the entire North American continent and parts of South America,
the Pacific and the Atlantic Ocean. I observed the eclipse near
Jackson, WY, in the Grand Teton National Park, Wyoming USA
under optimal conditions. Coordinates: 43.575520° N
-110.731235° W = 43° 34.5312' N, -110° 43.8741' W = 43° 34' 31.87"
N -110° 43' 52.43" W
For the photography I used a 500mm Telephoto lens f/8, a Canon
450D and EclipseDroid. The camera was
oriented so that the north direction is turned by 24° to the
left on the images below.
Click onto the images to enlarge!
In the partial phase it is easy to see
that sunspots are not really black, they are actually brighter
than the dark lunar limb, which is only illuminated only by
the earthshine.The latter, however, is
only appearing on long exposures during totality.
Second contact Corona HDR composite from 23
Prominences at third contact
It was worth to notify, that at third contact there were many
beautiful prominences at the western solar limb, but the eastern
limb at second contact did not show any of them. Longer
exposures reveal the coronal holes around the prominences
(picture lower right, 1/125s, ISO 100, 500mm
Diamond ring at third contact I also used an infrared modified
DSLR, the Canon 650D, with a ProPlanet 742nm Infrared filter to
capture the outer corona. The contrast was enhanced by a
Larson-Sekanina filter (30°, 10 pixels). Relatively strong lens flares were removed manually from the
In the picture on the left the ecliptic is marked by the
diagonal yellow line with marks every two degrees. In the
center there is a HDR image inserted.
You can see the extent of many thin streamers
and the diffuse background in the ecliptic plane.
On the left you see
an overlay image of six images with 1s exposure at ISO 400.
For the image below, four images with ISO 800 were
additionally blended. On the original picture, stars are recognizable
up to the approx. eighth magnitude. Lower, to
the right: A combined image of LASCO/SOHO, same image
section (image source: helioviewer.org).
I also tried a polarimetric
experiment, but some of the photos show in-motion unsharpness, due
to manipulation of the polarizer.
Left a contrast enhanced version of three exposures with 1/30 s
exposure time, f=500 mm f/8.
The color channels (Red, green, blue) are assigned to the three
orientations (0° 60°, 120°) of the polarizer. Colored arrows
indicate the angle of the polarizer (Electric vector).
Click to get a larger image with the original contrast.
Unfortunately, due to the in-motion unsharpness, the inner fine
structures cannot be evaluated.
1/2s exposure, ISO 100.
The polarization extends far into the coronal streamers in three
solar radii from the center. According tho the theory, the
polarization should decrease beyond two solar radii from center,
as the unpolarized light of the K-corona is greater than the
HDR composite of the above two
images with 1/30s and 1/2 s exposure time.
I've also built an
experiment to watch and record the eclipse
shadow bands. The shadow bands could be seen very impressively
on my projection screen.They became visible about three
minutes before the second contact. Unfortunately, one camera did not record the shadow
bands, the second camera has turned off
prematurely appr. 50 seconds before 2nd contact. The projection screen has a diameter of 1.08 m
(3.5 ft), at the lower edge is a calibration board in the
dimensions 20 x 15 cm (7.87 x 5.91 inches).
The image below shows a frame from the YouTube
video, the original image on the left, and the
contrast-enhanced version on the right.
Video of the shadow
bands before the second contact, taken with an LG G4.Split
screen, left side showing the original video (gamma
corrected), right side contrast enhanced by dividing an
average sequence and Gaussian noise reduction. Unfortunately, the video is affected by
vibrations caused by the periodic swaps of the sky light
intensity sensor (SQM).
dramatic changes of the landscape. Left: 19 seconds before the second contact.The lunar shadow is clearly visible above the
mountain range of the Tetons in a distance of 6 miles. Middle: Totality.To the south,
very beautiful the twilight colors could be seen. Right: 6 seconds after the third contact.
Photos: Courtesy Christian Strickling, LG G5
Fisheye photo, Peleng 8mm fisheye
f/5.6, Kodak ColorPlus 200 ISO negative film (Kodak
200-8), 17.5 s exposure at
As expected, the ground temperature is the strongest
as it reacts directly to the heating caused by heat radiation,
which is very variable during the eclipse.
It rose from a minimum of 13.4 ° C 9 minutes after maximum totality to over 36 ° C
after the eclipse. At 1.4 m height, the
excursion is much lower and also somewhat delayed. The minimum of 12.2 ° C was
reached 10 minutes after the middle of the eclipse,
the temperature rose above 25 ° C after the eclipse.
The temperature has already been 20°C before the eclipse. As expected, the relative humidity
changed inversely to the temperature, since a specific influence
of the eclipse on the water content of the air
was not to be expected.
The wind blew very weakly
on the eclipse day, with no appreciable gusts. An eclipse wind could not be measured during
this eclipse as well as in my other
eclipses. In the diagram below, there was
added a constant value of 10 m/s to the wind speed. Download my values here as csv file.
of the temperature and illumination during the central phase of
the eclipse. The minimum illuminance was almost 6 lux in the
center of the totality, slightly more than during the eclipse of
2016 in Indonesia (5 Lux there). This corresponded to the
illumination, which I could measure at a solar depression of -5°
34' below the horizon, just 29 minutes after sunset on August,
The air pressure
during the eclipse, as was measured by
three different Android smartphones (Samsung Galaxy S4, Galaxy
S5 and LG G4).The eclipse contacts are
marked in the graphic by thin vertical lines.Apart from the general trend of decreasing pressure on
eclipse day, there is no specific influence of the eclipse to
the air pressure recognizable.
To adjust the devices to each other a constant value of 2.0 mbar
was added to the values of th Galaxy S5.
With the help of a
sky brightness meter using the same sensor as the
well-known SQM, I measured and recorded the brightness in
different directions of the sky. It was measured in zenith (90 ° elevation), 15 ° and 45 °
elevation in all four main directions.
At the zenith, a
minimal brightness of 12.85 mag/arcsec2
was achieved during the totality.This corresponds
to the zenith brightness approximately 30 minutes after sunset
or before sunrise with a solar depression of -5.78 °. This is a
little bit lighter than my recording at the eclipse
flight 2015 or the eclipse 2012 in
Wuhan, China. The sensor in the 45° southern direction shows the
strongest rising and quickly saturates, since the sensor was
exposed to direct sunlight.Its value is therefore
only limited comparable to the other measurements.
For comparison (picture right): The curve of the
clear night in the Teton National Park from 08/18 to 08/19/2017.Magenta-colored vertical lines mark the twilight
times (civil, nautical and astronomical twilight). At 3 AM local
time (UTC -6h) I recorded 21.46 mag/arcsec2
as the darkest value. Download my values here as csv file.
To the left:
Graphic in higher temporal resolution of the central 6 minutes.
Details of the Eclipse
Details of the eclipse at my
location at Grand Teton National Park, as calculated by EclipseDroid: Mon, 2017 - 08 - 21 total solar eclipse
Jackson, +43.575520° -110.731235°
Altitude: 2000 m
Timezone: UTC +0,0 h, DeltaUTC = 68,95 s
Rise Azim Culm.
12:35 73° 19:26
Duration : 02:19,8
Magnitude : 1,0138 (101,4 % Diam.)
Coverage : 100,0 % (area)
Size Ratio : 1,0287 (Ø Moon/Ø Sun)
UmbralDepth: 95,8 %
Distance to centerline:
Distance to central limit: 50 km
Shadow speed and direction: 2961 km/h, 102°
Shad. Bands C2: 180°, C3: 175°
Global Events:Total solar eclipse
Maximum eclipse: 2017-08-21 18:25:31
dur.: 02:40,2 | +36.97°, 272.33°
P1: 15:46:51 U1: 16:48:36
U4: 20:02:34 P4: 21:04:23
Saros 145, gamma: 0,4367
RA: 10.066h DE: +11.87°
For details on this eclipse, the circumstances,
tips how and where to observe have a look at the Android App Eclipse
2017. For calculation of other eclipses you can use AstroWin for Windows or EclipseDroid for Android. The latter
is also good for controlling cameras and it is supporting
sophisticated observation programs.
The Great Eclipse 2017 is part of the Saros-Period 145,
which lasts from the year 1639 and will end with its eclipse number
73 in 3009. In a Saros period there will occur every 18 years and 11
1/3 days an eclipse. Depending on the number of leap years and after
a date line transgression the value may vary from 18 years and 10 to
12 days. It is containing 34 partial eclipses. The other 43 ones are
annular, hybrid or total, with durations between 00:50 minutes up to
7:12 in the year 2522. The image right is showing a Saros-snail,
indicating how the lunar shadow hits the earth at the maximum of
each eclipse. Click into the image to enlarge. It was created with
my Windows-software Sarosportrait.
There are always several Saros
cycles active, for example cycle
139 includes the coming total solar eclipse of 2024-04-08
in the USA and Canada. Their predecessor was the
eclipse in the Mediterranean of 2006-03-20.
The graphic on the left shows the eclipses over the years with
their appearance during the seasons.The eclipses are crossing once
in 19 years all the seasons, because the slightly inclined lunar
orbital plane is spinning once in this time. In
addition to the Saros cycle, the Metonic cycle is also shown.In this cycle the eclipses occur after 19 years on the same
date or with one day offset.However, the cycle
runs only briefly, after 38 years the series breaks off.It can also be seen that at least one lunar eclipse belongs
to every solar eclipse, occurring two weeks before or after the solar
one.However, this can
be one of the nearly invisible penumbral eclipses.