Heikki Kainulainen uploaded this reflection subsun a couple of days ago to the Finnish observation site Taivaanvahti. It was seen in the Muonio region of northern Finland on May 29. The photo was taken through window at 04:41 when the sun was 6.9 degrees above the horizon. In the direction of the sun there is, starting at 11 km distance from the observation site, a 3 km transect of water. This is lake Pallasjärvi, and could be the source of the reflection. It is the only large water body for 140 km in the sun direction.
However, according to Kainulainen, Pallasjärvi was still frozen. So maybe the reflection was from the lake ice, or, as Kainulainen suggest as one possiblity, from the possible flood waters in the bog areas.
As reflection subsuns go, this is a beautiful specimen which shows also the mysterious effects of vertical striation and larger-than-sun width. Below is an usmed close up of the photo above to highlight these features.
Yet one more image is shown, in which a separate photo of the sun has been superposed with the pillar. The width of the brightest part of the pillar is about equal with the sun disk, so this part most likely was located on the solar vertical. The sun reference photo was taken with the smallest aperture of the lens and shortest exposure time, but it may still be overexposed slightly.