The post whore thread.

[BuffCyclist]

We clean our mirrors with a CO2 "snow" (liquid CO2 which is passed through a nozzle and expanded rapidly to sublimate into a snowlike form that evaporates after about 18" once it leaves the tube), which knocks a majority of the dust off. The drive surfaces are cleaned/lubricated usually the same time. During the dusty/pollen seasons, they clean those every other day if its bad. When its not the dusty season, they try to clean once every other week. We realuminize our mirror every other year, or strip it down to the glass, then re-apply a 40-60 micron thick layer of aluminum that is the mirror's reflective surface.

Because we are a survey telescope, we clean more regularly than most telescopes, because we want the data throughout the 4-6 year surveys to be taken with nearly identical conditions, meaning a mirror between 0-2 dirty, instead of first year getting that and the dirtiness slowly increasing towards the end of the survey. And that is an arbitrary number.

[OtterbatHellcat]

Wow...now I know.

...and all I had to do, was ask.

[OtterbatHellcat]

In high school, I took an astronomy class...as an after school project, I started the grinding process for a reflector....it was quite a boring undertaking.

He was a cool instructor though, Mr. Nasser. Kinda had that Carl Sagan thing going.

[OtterbatHellcat]

Funny how many folks think Pleiades is the little dipper.

[BuffCyclist]

We have a cloud camera (infrared camera that looks at the sky) so we can monitor cloud conditions in real time. It is a downward pointing camera, and points at a hemispherical mirror, that was polished by hand by someone who used to work here. Another observer has built a 24" telescope. Its quite impressive.

[BuffCyclist]

Funny how many folks think Pleiades is the little dipper.

Random question for you, how many stars are in the Pleiades, and what is another name for it?

[BuffCyclist]

Hint, the number of stars is related to its other name...

[OtterbatHellcat]

I'm gonna say 7, but another name is not coming to mind.

[BuffCyclist]

The other name is the Seven Sisters.

Most people are misled by that because there are actually 9 stars, named after the Seven Sisters of greek mythology, and their two parents.

[BuffCyclist]

And what car company uses the Pleiades constellation in their logo?