mainline is right

From where was that Mainline photo taken?

Towards the top of P2 - I fixed and lowered to get the second coming through the roofs.

I will have the picture later, but it may not help much.

What mountain in the Catskills can be seen through the Minnewaska notch looking West from the top of Millbrook?

More to the NW. What appears to be a large peak rising immediately from the Rondout Valley? Ashokan High Point.

I would say "no", i think there is only one mountain you can see thorugh the notch, and I think I have the right answer. Perhaps the best way to go about this this is backwards.

Slide Mountain?

"Guess the route" means someone posts a picture of someone climbing some route in the Gunks and others try to guess the name of the rock climbing route. It's not a thought experiment about vague descriptions of some random nearby hill. It's really not that difficult a concept.

OK, I will take a picture.

That's the first part....but remember the rest:

...of someone climbing some route (climbing, not looking at a mountain) in the Gunks (not the Catskills or anywhere else) and others try to guess the name of the rock climbing route. It's not a thought experiment about vague descriptions of some random nearby hill.

Over 280 pages, thousands of views, and wide participation, you seem to be the only one having difficulty with the concept.

To get back on track, how about this photo from the Mohonk Preserve climbing page:

(even though I don't have a definitive answer)