Kievan Elliptical Halo
|Roman Yagodka's halo is approximately 5.9° x 4° with the moon off centre in the oval - a characteristic elliptical halo shape. Elliptical halos become less oval as the moon or sun increases in altitude. Here the moon was 39° high. The star to the left is Regulus.
The halos might be generated by varieties of the crystallographically rather improbable pyramidal crystal at right.
Several ray paths between its faces can generate oval arcs. However, ray tracing simulations are never fully satisfactory.
Roman used a 1/8s exposure at f/4 and ISO 3200, equivalent 35mm focal length of 75mm.