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Fig. 8

image

Optical variability: combined optical spectra of PG 0043+039 taken with the HET and SALT telescopes in 2013, an optical spectrum taken with the KPNO in 1990, as well as the difference between the spectra taken in 2013 and 1990 (additionally shifted by 0.6). A horizontal line is added to the difference spectrum to guide the eye.

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