Recent content by gloglo

Thank you for answers. I always let the primary mirror cool naturally a couple of hours, before I stow all the parts (Dobsonian) for a short ride to my favourite secret dark observing site, away from street lamps and stray light. A matter of 10 minutes´ride. Then it is assembled, its small fans...

As an amateur astronomer I want my primary mirror (diameter 37 cm) to maintain the same temperature as the air. Small fans on the backside do the job. Only, the air cools quicker during the night than the 1.5 cm thick glass. Do I obtain a slightly lower temperature on the backside by sticking...