I finally got around to replacing the primary mirror in my f4.5 16″ telescope. The mirror was damaged by some hard water that corroded the coating. The mirror figuring still seems great, but it needs to be recoated.

I was able to source a replacement f4.5 16″ mirror, so I can then get the original mirror refigured and coated and have a spare.

I still need to do the center marking on the new mirror, as that is really needed to get a good laser collimation. I purchased a really cool template to help with the center location marking. I also took the opportunity to replace the cooling fan under the mirror. The fan is used to cool the mirror down since the mass of the mirror will usually prevent it from cooling down as fast as the surrounding air, and that temperature differential creates tube currents that distort the wavefront.