This turns out to be a challenging target for me. I get internal optical train reflections (I believe from Alnitak being so bright). As a result longer exposure times make the reflections obvious, and I'm not sure how to remove the reflections with my equipment.
Only ~35 minutes of exposure time before freezing fog rolled in.
EdgeHD8" w/0.7x focal reducer
Orion Atlas w/Polemaster unguided
Ha modified Canon T2i
16x 120sec exposures