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Total Solar Eclipse of 8 April 2024 USA - Arkansas, Nimrod Lake, +34°57'50.7" N, 93°12'35.8" W, 80 m a.s.l. Local circumstances: C1 17.32.30, C2 18.49.31, max 18.51.39, C3 18.53.47, C4 20.10.24 UT, dur 4m17s by Lorenzo Comolli, Emmanuele Sordini, Alessandro Gambaro |
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Click on the image for high res version. MOUSE OVER for star magnitudes. Look also to the hires with star magnitudes. |
The HDR
corona at large field of view. Image setup piggybacked
on the TEC140 mount. Setup composed of a Canon 100-400
photographic lens set at 150 mm focal length and a
Canon 6D camera with Magic Lantern software onboard
and controlled via an internal eclipse script. Many
stars are visible thanks to the large field of vew.
The center of the image (Moon, prominences and the
very inner corona only) are from the TEC140+ASI6200MM
setup. Canon 100-400 lens set at 150 mm f/5.6, Canon 6D magic lantern, ZWO AM5 mount (setup mounted on the same mount of TEC140, on the counterweight bar, exposures from 8 ms (1/125 s) to 1 s at 1 EV stops at 400 ISO, 244 single RAW images captured during totality. Image processing by Lorenzo Comolli. Image setup controlled by Lorenzo Comolli and prepared by Emmanuele Sordini. This image is a collaboration between Lorenzo Comolli, Emmanuele Sordini and Alessandro Gambaro. |
Click for hires |
The HDR
corona with medium field of view. Obtained with a
"standard" setup, i.e. a Canon reflex camera, while
most of the other images from this expedition where
obtained with astronomical CMOS cameras (like the
ASI6200MM on top). The difference in the noise and
details is quite noticeable. This image was also
penalized by a bad flat field that increased the noise
and reduced the visibility of fine details. With the
same setup we shot also the 2017
and 2019 eclipses. Pentax 75 apochromatic refractor (FL=500 mm, dia 75mm f/6.7), Canon 90D (32 Mpix, RAW files), Kenko NES mount, exposures between 1/250 s and 1 s at 200 ISO, plus 1 s at 400 ISO. 177 total exposures were used. Image processing by Lorenzo Comolli. Image setup controlled by Emmanuele Sordini. This image is a collaboration between Lorenzo Comolli, Emmanuele Sordini and Alessandro Gambaro. |
A solar
eclipse greatly influences the Earth atmospere. The
temperature, relative humidity, luminance data show
typical trends, peculiar to each eclipse and location.
During this eclipse I've used a T/RH datalogger with the sensors positioned at 1 m heigth on a small tree, on the side in shadow from the Sun light. This way data are quite reliable and much less influenced by the ground temperature respect to the measurements I've made in the past eclipses. In this eclipse I've found a 5°C decrease, to be compared to 9°C in 2017 USA Wyoming, to 4°C in 2006 Egypt, to 7°C in 1999 Hungary. A digital luxmeter measured the horizontal luminance: this is a really interesting measurement, that show the tremendous fall of the light, between full Sun at 110000 lux and totality at only 1.8 lux, to be compared to 3.4 lux 2017 USA Wyoming, 4.1 lux 2006 Egypt. The lower value, in my opinion, is due to 2 reasons: first the eclipse was quite long and deep (as confirmed by the SQM reading below), and second the selected location was surrounded by many trees, reducing the ambient light coming from the horizon. During totality I've measured the sky brightness with a SQM-L, obtaining 13.56 mag/arcsec^2, that is equivalent to the twilight sky when the Sun altitude is -6°C, i.e. civil twilight. Do you what to feel how dark is the sky during totality? Wait for the civil twilight, that is about 30 min after sunset! Here are the plots of:
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Click for the PDF presentation |
If
you're interested in processing your HDR corona, I invite
you to follow the tutorial that Lorenzo Comolli prepared
after the USA 2017 eclipse. On 27 January 2018 Lorenzo was
invited by VVS association in Belgium for presenting at
the Astrofotografiedag 2018, a conference about
astrophotography. One of the presentations was on how to
process the great American eclipse. Look
also to the other presentation on the dedicated page. |
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