Condensation on Detector Window

Saturday, February 17, 2018 3:10 PM

Problem(s) Encountered:

The faceplate had condensation on it and I attempted to remove it using dry nitrogen which seemed to help a little bit but the center of the faceplate still seemed out of focus with large out of focus spots despite stars on the outside of the plate being in focus. I pointed the telescope down so that I could see the mirror and it looked fine. I tried to just take some observations to see if the remaining condensation would go down on its own but it never did. Humidity then rose above the limit again and I closed the telescope.


Dry N2 was not run long enough to remove all condensation.  N2 run times can be as long as 20-25 minutes if condensation/humidity is bad enough, although typically ~15 minutes should suffice.  The problem is more pronounced for large-format CCD’s, such as the 4K detectors.