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Disassembling the ASH 17" classical Cassegrain

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#1 Dave Mitsky

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Posted 08 January 2019 - 08:40 PM

These are some of the photos that I took when fellow ASH members and I disassembled our 17" f/15 classical Cassegrain last month in order to recoat the primary and secondary mirrors and refurbish the OTA.

Dave Mitsky

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#2 Jim Waters

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Posted 08 January 2019 - 08:46 PM

Nice weekend project...  I wish I could have been there to help.  Thanks for posting.



#3 Tyson M

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Posted 08 January 2019 - 10:00 PM

What a cool scope!  It would be a pleasure to use that under the stars! 



#4 Dave Mitsky

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Posted 08 January 2019 - 11:45 PM

Unfortunately, the skies at our observatory have been steadily degrading since the early 1990s and at even greater rate in recent years.


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#5 Starman27

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Posted 09 January 2019 - 02:59 PM

I thought I had problems disassembling my 10 inch classical cass. You did good. Sorry to hear about your skies.



#6 macdonjh

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Posted 10 January 2019 - 11:57 AM

You mount looks so lonely.  I hope the mirrors are done soon so you can put the scope back.  What are your plans for the OTA?

 

That primary baffle tube is so short!

 

Sorry to hear about your skies, too.  I hope you can at least get good planetary views.  If your skies are at least steady (even if plagued by light pollution), I'm sure that scope is a monster on planets and the moon.  Your club's observatory is so clean and uncluttered.  Lots of room for walking around the scope.



#7 Dana in Philly

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Posted 10 January 2019 - 12:08 PM

How often have you had to recoat the mirrors and do this refurbishment?



#8 Dave Mitsky

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Posted 10 January 2019 - 02:14 PM

That primary baffle tube is so short!

That's not the baffle tube.  It's where the baffle tube is attached.  

 

The baffle tube is shown in this photo.

The OTA is being repainted inside and out.

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#9 Dave Mitsky

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Posted 10 January 2019 - 02:19 PM

Sorry to hear about your skies, too.  I hope you can at least get good planetary views.

The observatory lies in an orange zone.  The summer Milky Way is visible but not prominent on transparent nights (SQM readings around 20.4) and I can still see M33 with binoculars so the skies aren't completely hopeless for DSO observing.  Back in the early 1990s, the Pipe Nebula was visible with binoculars on very good nights but those days (nights?) are long gone.
  

I observed over half of the Herschel 400 list with the 17" classical Cassegrain during the late 1990s and early 2000s.  Star-hopping with a telescope that has a focal length of 6477mm and a minimum magnification of 116x is a lot of fun. wink.gif

 

The planetary views can be quite good when the seeing cooperates.


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#10 Dave Mitsky

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Posted 10 January 2019 - 02:27 PM

How often have you had to recoat the mirrors and do this refurbishment?

This is the first time since 1995 or so to the best of my knowledge.




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