AST Heater for glued Newtonian secondary mirrors with holder D=50 mm

AST Optics Heating Sleeve for glued secondary mirrors

The heater solves the problem of dew-covered secondary mirrors by moderate heating of the back. Rising the temperature by only a few degrees prevents dew formation of the mirror surface and extends the oberving or astrophotography session.

How is the heating sleeve attached:

The sleeve is wrapped around the shaft to which the secondary is glued, black side outwards. With the flexible Velcro tape, the sleeve is well secured. Then, the cable is led to the outside along one spider vane.

The heater is suitable for the following telescopes:

Optimal for attaching are telescopes with glued secondaries with a shaft diameter of 2" or 50 mm. The sleeve is rather flexible, though, so a bit larger or smaller holders can be used. The heater is well suited for GSO Newtonian telescopes, but also for UNC and larger ONTC Newtonians.

Practical tip from TS for using the heating sleeve:

We recommend a low setting at the controller for producing minimum heat. Indeed, the heat is transferred well targeted to the secondary mirror by the holder, but too much heating would result in air turbulence and cause tube seeing.

But if the secondary is covered with dew, then only maximum heating power helps to get rid of it. According to the motto: better slightly thicker stars than no stars at all. After the secondary is clear again, you can reduce the heating power.