INAF-OATo Eclipse Expedition, 11th July 2010

Solar physicists of the Turin Astronomical Observatory of the National Institute for Astrophysics (INAF) have successfully observed the total solar eclipse(Fig. 1), on July 11th, 2010, from Tatakoto, an atoll of the French Polynesia (Fig. 2). The INAF-Turin team has organized the Italian expedition that included physicists from the Val d’Aosta Observatory and the University of Florence. The expedition was part of an international program involving the University of Hawaii and NASA Goddard Space Flight Center.

 

 

The main experiment of the expedition was the observation of the spectrum and polarization of the coronal “Green Line”, emitted by 13-times ionized iron atoms, at the wavelength of 530.3 nm. Silvano Fineschi, expedition leader of the INAF-Turin team, together with Giuseppe Massone, Gerardo Capobianco and Carlo Benna, have developed the spectro-polarimeter based on a novel electro-optical filter with liquid crystals that was successfully tested during the eclipse (Fig. 3). Marco Romoli, Lapo Casetti (University of Florence) and Paolo Calcidese (Val d’Aosta Observatory) provided important context observations of the visible-light corona.

 

 

  Figure 4
“Green Line” of the INAF-Turin instrument (green shades), and those
in broad-band visible-light camera of the Univ. of Florence (grey shades)
bridge the gap between the field-of-view of the space-based coronagraph
LASCO-C2 (red shades) and the extreme-UV disk-imager EIT
(orange shades) onboard of SOHO.

 

The INAF-Turin, liquid-crystal filter tested in this eclipse is a prototype of the instrument for the coronagraph ASPIICS selected by the European Space Agency (ESA) for the Proba-3 formation-flying mission, scheduled for launch in 2014 (http://www.esa.int/SPECIALS/Proba/SEMJQC0OWUF_0.html ).
The 150-m separation of the two Proba-3 spacecrafts will create an artificial eclipse when the occulter on one of the spacecrafts will cast its shadow on the other spacecraft with the ASPIICS coronagraph onboard, allowing in this way eclipse-like observations of the corona (http://www.esa.int/SPECIALS/Proba/SEMTA27JT2G_0.html ). 
The July 11th eclipse provided the INAF-Turin team with the opportunity of testing also a liquid-crystal, broad-band polarimeter that is part of an ESA program for space-validation of liquid-crystal electro-optics.
The liquid-crystal polarimeter is part of METIS, the Italian coronagraph selected by ESA for Solar Orbiter mission, scheduled for launch in 2017 (http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=40396). Ester Antonucci of INAF-Turin is the METIS Principal Investigator.