Stargazing & Bikepacking

Not-so expensive astronomy and some bikepacking stories

Mirror’s back!

Rejoice for I got my primary mirror back! The new coating did not turn out perfectly. #sadpanda Something’s wrong with the coating but what exactly is going on is unknown. It looks like oxidation and I’ve been offered a re-coat for free. But that’s something I won’t do before spring 2019. First I have some observing to do!

The mirror cell also has had some TLC. The base plate has been replaced because it was a bit too large and did not fit nicely fit the tube. Also, one of the holes for the collimation screws was off which resulted in not-so-smooth collimation. Both have been fixed.

The primary mirror itself is glued to the base plate using three dots of silicon glue. I used Plop to determine where to put the dots. Three side supports also have been added using a simple L-shaped piece of steel with cork between the mirror and support. Of course the supports only loosely hold the mirror. And I added a centre dot.

This week I also added a 40mm 12V fan to cool the primary mirror a bit faster.

I was surprised to see it could well take up to over 2 hours to cool this mirror made of 37mm thick borosilica glass. Now it should take half as long or maybe even less, according to some Cruxis tool I found online.

If only those blimmin’ clouds would go away….


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