Water, Water, Everywhere

As I am located in the New Forest, you can imagine that for some months of the year, particularly from late September until late November, condensation is a major problem in the dome. 

I have always used a product called “Water Eaters” from Lakeland Plastics [I prefer the name “Water Snake” but I guess the marketing people at Lakeland didn’t] around the gap where the dome rotates.  This product is basically a sausage-shaped piece of fabric filled with some water absorbing substance [possibly silica-gel]. 

I always place these in the gap around the dome edge [on the inside of the dome] after an imaging session and they keep the ingress of water vapour right down.  Unfortunately, on their own they are still not enough! 

I had a problem with the Hyperstar a couple of years back where halos started appearing around bright stars after about half an hour or so of imaging.  At first I thought this was atmospheric water vapour.  After quite a bit of investigation I found out it was actually water vapour in the Hyperstar itself – not good! 

I got rid of the trapped water vapour by placing the Hyperstar in an oven at 40C for about an hour, but I clearly needed to also do something about protecting the observatory. 

To this end I bought a dehumidifier which now runs full-time in the dome.  I typically need to empty the water container every three days [roughly a gallon I suspect] throughout the year. 

I also have a thermostatically controlled greenhouse heater in the dome which is used to keep the dome temperature a few degrees above freezing during the winter months.

So far, these precautions seem to be working – I’ll find out this coming winter  🙂

Have you had similar problems?  If so, how have you deal with them.  Drop me a line and let me know.

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2 Responses to Water, Water, Everywhere

  1. Torcuill says:

    Aberdeen Astronomical Society has a 10ft steel container at our dark sky site, and it used to get terrible condensation like you describe until we increased through ventilation. This might save you some leccy!

  2. Greg Parker says:

    Thank you for the suggestion. There was plenty of ventilation in the fibreglass dome – there is a 2″ gap all around the dome edge where the runners lie. It’s just the humidity in the New Forest that causes the problem. With water absorbers running around the dome edge the dehumidifier doesn’t have to work too hard to keep the air bone dry.

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