Observing out in the cold

[Nimrodel]

Hi all! Just wondering about if there is any problems using the telescope out in the cold - I am talking about when it is around -15 to -20 celsius? Live in Norway and sometimes it gets very cold where I live. I've got a SW Explorer 250pds on a NEQ6 goto mount.

[mikeDnight]

When the outside temperature is very low, it will take longer for a scope to reach thermal stability. Optics may also freeze over on some scopes. I doubt you'll do any damage to any telescope by observing in extreme low temperatures. Just remember not to cap the scope if the optics are fogged over or there's ice on the lens or mirror! Leave them uncapped in the house until they have cleared naturally.

Mike

[BGazing]

Well, I imagine at -20 at least the air will be nice and dry and clear. 

Batteries' will be draining really fast. My Evo battery is basically halved at -4, I imagine at -15 it would be really taxing on it. Never used it at -15 and -20 so I have no idea whether it would be feasible at all. Check the Goto manual.

Possible dewing on the EPs, frost on mirror. Follow the advice above.

In winter, always dress 20 deg lower than the actual temperature.

I am sure others will have better advice than I do.

[MarkyD]

Any grease that isn't rated for low temps in the mount gears/bearings will thicken and could put strain on the steppers and running gear.  Wrap the mount in a thermal liner to keep some heat in

[Nimrodel]

Thanks Fingers crossed it will not be as cold this winter, today it's only -5 celsius. Hopefully clear skies tonight...