echt wel erg zeldzaam: eerste beschrijving is van 1987

"In December 1987 two Finnish amateur astronomers observed and photographed a peculiar vertically elliptical ring surrounding the moon. A literature study carried out soon after this first observation brought to light ten reported historical cases of this type of rare halo phenomenon. It was found out that the existence of these elliptical halos has been uncertain to date due to a lack of photographic evidence. One indication of this is that none of the major modern works on halos mentions such phenomena. During 1988 three more elliptical halos were seen by the Finnish halo observing network. Observations and photographs taken of these phenomena seem to indicate that at least two types of elliptical halo exist. The smaller one was first reported by US astronomer Frank Schlesinger in 1908 and its vertical axis has in all four possible cases been about 7°. No name has been suggested for this halo. The larger one seems to have a vertical axis of about 10° and it has been called the 'halo of Hissink' by Dutch halo observers. Outside the Netherlands this rare halo has received little attention."

(Hakumaki, J., and Pekkola, M.; "Rare Vertically Elliptical Halos," Weather, 44: 466, 1989.)