See the Getting There section on the main Observatory Rock page.
From the trailhead area which is shown in the signature photo, head north up through the trees. Once in the aspens you will come across the remnants of an old teepee frame and a small wooden paddock. Head up past this neat little area.
There is no trail so a little route finding is needed. The goal is to head up until you reach the ridge a few hundred feet to the west of the summit. This will allow you to avoid the vertical south face of Observatory Rock. Pick a route that feels best for you.
As you head up the south slopes and see the vertical south face of Observatory Rock you may doubt the existence of a non-technical route. Pick your way up to the ridge staying well to the west of the sheer south face.
Once on the ridge you can proceed east towards the summit staying to the north of some very large rock outcroppings. You will eventually come to the bottom of the west summit gulley which is protected by a huge pine tree that seems out of place. The huge trunk is nearly three feet wide and branches into three smaller branches not for above the ground. Pass under one of the branches and up into the gulley. The gulley is mostly Class 2 with the upper portion becoming Class 2+ with a short section that could be considered easy Class 3. Once on top the views are amazing.
Standard hiking gear will for typical conditions. The off-trail scrambling nature of the entire route warrants hiking boots with good ankle support. Bring a camera and binoculars - you will be glad to have them.
If you have information about this route that doesn't pertain to any of the other sections, please add it here.