NGC253 from Astrofest

[Hagar (Doug)]

Very nice Peter, Just what I have come to expect from you. Lovely sharp, clean, noise free and detailed image.

Well done again.

[RobF (Rob)]

Yep - very very nice Peter.....

[peter_4059 (Peter)]

Thanks Paul, Allan, Wes, Doug and Rob.

Originally Posted by Zubenel

From a visual observers perspective ,great to see a a good image taken off mirrors!!

I found the dew quite challenging this year - especially the primary mirror and this shows in a number of the images I took later in the night/early morning unfortunately.

I've seen dew heaters for the secondary but not for primary mirrors - anyone got a way to avoid this problem when imaging?

[jjjnettie (Jeanette)]

Yeah, I hear you Peter.
What a pain!
I just carefully poke the hairdryer between the vanes and blow it away.
Hopefully we won't have to worry about it again for another 9 months.

[AlexN]

I've seen people wrap a long heater band around the tube right at the very bottom to warm the area around the primary. I do not know however how effective that would be... If you're not adverse to pulling the scope apart, you could always fit a heater band to the mirror itself and have the cable for it coming out either through the tube or something like that.. The problem would be internal thermal currents then... not to mention that the outer edges of the mirror would be much warmer than the center... Maybe you could make a heat pad that sicks to the bottom of the primary mirror and heats the mirror from the center... This way the temperature would not have to be as high in order to remove dew from the area that your camera sees the most.. it would lessen the internal currents a bit I imagine, but you would still get a boundary layer of warm air on top of the mirror.. Its a tricky prediciment with newts...

Did you have the fan running? I would have thought the fan would create enough positive pressure into the tube to stop the ingress of dew?

[peter_4059 (Peter)]

I tried with and without the fan but same problem. I think with the fan you are still drawing in wet air and it's going to condense on the mirror. I thought about heater pads on the mirror but you don't see them commercially available - I guess for a good reason. I also tried heating the air going into the fan in an attempt to warm the mirror and remove the dew but the hair drier didn't have enough power to raise the mirror temperature enough.

[AlexN]

Hmmm.. a difficult situation indeed... Hope you figure something out!! Dew is indeed the enemy...

I've just organised a pair of heater bands for my refractors and a controller... I believe I've now vanquished my main enemy... Now.. How to remove clouds and destroy the moon in one fell swoop..

[Octane (Humayun)]

Peter,

Wow, lots of dark dusty detail there.

I'd make a suggestion to brighten the image up a little, but, that's a personal preference.

Regards,
Humayun