Used:Cleaning the mirror surface: first blow off the dust that can be blown off with a blown balloon, then use a good quality absorbent cotton to dip the alcohol and gently wipe the mirror.

After drying, look at the light source from the side to see if there is some cotton or Keep the water stains on top, and if necessary, gently wipe them with some good quality mirror cloth (be careful, otherwise it will affect your telescope).