Sun's Corona in High-Dynamic Range from La Silla's Observatory - TSE 2019

On July 2, 2019, a Total Solar Eclipse occurred over South America, plunging professional observatories across Chile into darkness for up to 2 minutes 30 seconds. The path of the moon's shadow just passed over the ESO's La Silla ESO Observatory: a unique event which is not about to happen until 212 years! AstroSpace was part of the MeetESO team who observed the eclipse from this historical place. Find below a selection of our best images.

Sun's Corona in High Dynamic Range

This picture taken by Guillaume Doyen (the writer) highlights both the new Moon's Earthshine and the filament-like structure of the highest layer of Sun's atmosphere called corona. Composed of ionized gas (plasma), the corona is about 10 million times less dense than the sun's surface, making it too faint to be observed for Earth observers except when Sunlight is directly blocked, that is to say during a solar eclipse.
As it is made of charged particles (protons and electrons), the corona interacts with the strong magnetic field produced by the Sun and moves along the magnetic field lines.
Even during an eclipse, capturing the details visible from the inner to the outer corona remains a tough challenge since the brightness of the corona varies with respect to its distance from the surface.

Technique and equipment

Image n'ayant gardée que les détails de la couronne solaire.

To obtain this result, a specific software processing imagined by american scientist Fred Espenak was followed and applied. It combines two methods: the standard High Dynamic Range (HDR) technique we use regularly in photography and a dedicated technique for improving details within the corona by using a radial blur filter.

Guillaume captured a series of 10 images taken during totality with different exposure times, ranging from 1/4000 th second to 1,3 seconds with a ISO 200 sensitivity.
A Canon EOS 700D camera and a Sigma 120-300 mm F/2.8 HSM lens stopped to F/4 @300 mm were used and mounted on a standard tripod.

As no tracking mount was used, the alignment of each frame was manually performed, with a required accuracy of one pixel !

HDR image with natural rendering.

Real-time 4K footage of the Total Solar Eclipse

Evolution of the Moon's shadow over La Silla Observatory

This wide angle image sequel was taken before, during and after the totality period using a Canon EOS 6D camera and a Sigma Art 14 mm F/1.8 lens. The final video time lapse is visible here.