Wow! You haven't gotten much serious advice, have you? Who knew
the pooch could bring out such...passionate...responses.

If you have an "interior," room in your house, place the dog in that
room, with their bed. By interior, I mean no outside walls, and no
windows. They should not be able to hear outside (i.e., the owl)
noise from this room.

If being away from you will result in barking, try putting the dog
where it normally sleeps, but put a portable fan near it. This will
create white noise, preventing the dog from hearing the owl. Fan
should not oscillate, as that affects the noise it produces. Needs to
be high speed and steady (pointed away from the dog of course).

Finally, as a training method to stop barking, fill an empty, clean
spray bottle with water. Whenever the dog barks, say "NO" in a low,
firm voice and spray the dog in the face. It has to be a new spray
bottle (reused is too risky because you might not get it clean
enough). This was recommended to us in obedience school. Sounds
mean, but our Labradoodle learned very quickly. ‘Course, our Lhasa
Apso was another story...god help you if you have one of those!
(laugh)

Good luck.