When I gave the sun another look 6 days later, the group went westwards (upper right) following the 27 day (earth-centered) solar rotation. I thought the sun spot group had faded by then, but to my surprise this solar activity hot spot even grew in both size and complexity.

The reason for the upward rotation is the fact that I oriented the frame along the earth axis (north is up), which is tilted at some 23 degrees against the solar north pole. Only at the solstices the sun's and the earth's north poles are apparently aligned.

Again, I observed from my balcony in Vienna. On both mornings I took a series of frames with my 80/600 mm refractor extended to 1280 mm focal length.