Yesterday in the early morning I observed this galaxy with my 20" Dobsonian at 256x magnification. It was a tough object. With averted vision I intermittently saw a faint and diffuse patch at the right position. The fascinating aspect is that it is located just beyond the local group rather than next to NGC 4866.
Please find attached my sketch.

Clear skies

Robin

UGC8091NGC4866Robin.jpg