Search

The solar corona is the outer layer of the Sun's atmosphere. The brightness of the solar corona is a million times lower than that of the solar disk. The Earth's sky brightness itself is high enough to cover the coronal signal during ground-based observations. For this reason, the study of sky characteristics plays a fundamental role in observing the solar corona. To date, the only place with the sky characteristics that allow continuous coronagraphic measurements from Earth is at the MLO (Mauna Loa Observatory; Hawaii, ≈ 3400 m above sea level). This paper shows the results obtained as part of the "Extreme Solar Coronagraphy Antarctic Program Experiment" (ESCAPE) at Concordia Base, Antarctica (Dome C plateau-coord.: 75∘06′ S, 123∘20′ E, ≈ 3300 m above sea level) during the 37th campaign and gives a summary of all the sky-brightness measurements obtained from this site (34th and 35th campaigns). Dome C is confirmed to be a coronagraphic site with a sky brightness of about 1 × 10 − 6 B ⊙ . For the first time, it was also possible to detect a coronal signal and to compare it with what was measured by the COronal Solar Magnetism Observatory (COSMO) K-coronagraph (K-Cor) at the MLO. All these results were obtained by using a micropolarizer camera mounted within a coronagraph designed for Antarctic environments. [ABSTRACT FROM AUTHOR]

The evaluation of sky characteristics plays a fundamental role for many astrophysical experiments and ground-based observations. In solar physics, the main requirement for such observations is a very low sky brightness value, less than 10 − 6 of the solar disk brightness ( B ⊙ ). Few places match such a requirement for ground-based, out-of-eclipse coronagraphic measurements. One of these places is, for instance, the Mauna Loa Observatory (≈ 3400 m a.s.l.). Another candidate coronagraphic site is the Dome C plateau in Antarctica. In this article, we show the first results of the sky brightness measurements at Dome C with the Extreme Solar Coronagraphy Antarctic Program Experiment (ESCAPE) at the Italian–French Concordia Station, on Dome C, Antarctica (≈ 3300 m a.s.l.) during the 34th and 35th summer Campaigns of the Italian Piano Nazionale Ricerche Antartiche (PNRA). The sky brightness measurements were carried out with the internally occulted Antarctic coronagraph AntarctiCor. In optimal atmospheric conditions the sky brightness of Dome C has reached values of the order of 1.0 – 0.7 × 10 − 6 B ⊙ . [ABSTRACT FROM AUTHOR]