Total lunar eclipse January 2019 spectra

The brightness of the Moon dimmed by 10.75m during umbral eclipse. We found both branches of the O_2_ A-band almost completely saturated as well as a strong increase of H_2_O absorption during totality. A pseudo O_2_ emission feature remained at a wavelength of 7618{AA}, but it is actually only a residual from different P-branch and R-branch absorptions.

It nevertheless traces the eclipse. The deep penumbral spectra show significant excess absorption from the NaI 5890{AA} doublet, the CaII infrared triplet around 8600{AA}, and the KI line at 7699{AA} in addition to several hyper-fine-structure lines of MnI and even from BaII. The detections of the latter two elements are likely due to an untypical solar center-to-limb eect rather than Earth's atmosphere.

The absorption in CaII and KI remained visible throughout umbral eclipse. Our radial velocities trace a wavelength dependent Rossiter-McLaughlin eect of the Earth eclipsing the Sun as seen from the Tycho crater and thereby confirm earlier observations. A small continuum polarization of the O_2_ A-band of 0.12% during umbral eclipse was detected at 6.3.

No line polarization of the O_2_ A-band, or any other spectral-line feature, is detected outside nor inside eclipse. It places an upper limit of 0.2% on the degree of line polarization during transmission through Earth's atmosphere and magnetosphere.