Figure 2. The spectrum of the prominence
We had the opportunity to take spectra of the corona and of one prominence of the sun during the eclipse of 2 of July 2019. We observed the eclipse from the ESO La Silla Observatory in Chile. The results are shown in Figures 1 and 2.
The corona shows the “classical” iron (Fe-XIV and F-X) and H-alpha lines. The He line at 587.6nm is barely visible.
However, in the spectrum of the prominence, we found interesting features: the calcium Ca II were well detected with BACHES. Five Helium lines and the four hydrogen lines (Balmer series) are also well present.
The spectra were recorded with a BACHES spectrograph attached to a 11 inches Celestron telescope as shown in Figure 3.
Figure 3. BACHES spectrograph attached to a 11″ telescope
Telescope: Celestron 11″, F/10, equatorial mount
Spectrograph: BACHES from Baader-Planetarium, F/10, 50 x 125 microns slit (3.7 x 9.2 arcsec sky aperture), Resolving power 11 000, Spectral range: 393 – 707 nm
CCD camera: SBIG ST1603ME. CCD temperature set to -10C,
Calibration unit: RCU from Baader-Planetarium, Thorium-Argon hollow cathode and halogen lamps linked with a 300 microns optical fiber for spectral calibration and for order identification respectively.
Before the totality of the eclipse, the telescope was covered with a filter density film (Mylar sheet) with an optical density of OD-5 to protect the instrument and our sight.
In total 13 exposures of 5 seconds, each (plus 3 seconds download) were taken during the totality of the eclipse. The duration of the totality of the eclipse was only 1 minute and 50 seconds!
We placed the slit of BACHES close to the north pole of the Sun. Some pointing adjustments were needed to correct the drift of the telescope due to poor South Pole alignment of the equatorial mount.
3 of these 13 exposures showed partial illumination of the slit of a solar protuberance. The remaining 10 exposures recorded only the much weaker corona spectrum.
Echelle format was composed of 25 orders covering a continuous wavelength range of 393-707 nm. Results of both, protuberance and corona spectra were reduced with ESO-MIDAS software.
European Southern Observatory
“Spectra of solar corona and prominence during July 2nd, 2019 solar eclipse ” by CAOS group is licensed under a Creative Commons Attribution-Non-Commercial-No Derivative Works 3.0 Germany License.
Based on a work at spectroscopy.wordpress.com.