Implications for preferred longitudes in the coronal optical intensities

Abstract From the analysis of the optical intensities of the solar corona in various spectral emissions obtained by the Pic-du-Midi and Kislovodsk observatories has been derived that systematic North-South and East-West asymmetries appear in all the data sets. The combination of these two asymmetries makes the Northeast/Southeast solar quarters to appear brighter than the rest in most of the cases of all the data sets. It is very possible the excess of the Northeast/Southeast solar quarter to coincide with the preferred longitudes effect which has been mentioned by several authors in the past.