Goto Optical Coelostat
Posted 18 September 2012 - 09:09 PM
Posted 18 September 2012 - 09:10 PM
Almost 40 years old and it is basically perfect. Not even a scratch on the wood
Posted 18 September 2012 - 09:11 PM
Posted 18 September 2012 - 09:16 PM
Posted 18 September 2012 - 09:18 PM
Posted 18 September 2012 - 09:22 PM
Posted 18 September 2012 - 09:27 PM
One, the only missing piece is the focus tube to ocular holder adapter. I have tons of Goto parts, but not this one. I even have a very nice homemade adapter machined from aluminum...but the output is 1.25".
Two, the seller said it came with instructions. The instructions are on how to use the 80mm f15 scope for astronomical use on an EQ mount. No instructions for the Coelostat. I have only intuition to go on and I sure could use some help intuitizing Here is an article to get started.. Coelostat
Posted 18 September 2012 - 10:14 PM
Keep us posted on how
Never seen one in person.
Posted 18 September 2012 - 10:34 PM
Posted 18 September 2012 - 10:38 PM
Posted 19 September 2012 - 12:05 AM
Have you cleaned/de-fungused the objective yet?
Posted 19 September 2012 - 12:11 AM
I fixed the link. If you click on "print this page", it brings up a pdf that is easier to read.
Posted 19 September 2012 - 04:40 AM
Posted 19 September 2012 - 07:58 AM
Posted 19 September 2012 - 08:32 AM
Posted 19 September 2012 - 09:36 AM
Great find. You now need to find the GOTO prominence attachment to go with it.
A couple of tips since I'm restoring a Hale spectrohelioscope that will soon be installed at Stellafane and (See ATM-1 for the design) it uses the same Coelostat configuration. First the flats need to be very good optically and at least 1/10 wave or better or they will introduce astigmatism into the image.
The rail system for the second mirror which reflects the light into the telescope is used to compensate for the changing DEC of the Sun through the year, so every few days you'll need to adjust it either closer to or farther away from the objective depending on the time of year. Also there needs to be a way to relocate the tracking mirror from the East side of the bracket to the West side or you won't be able to track the Sun after it passes thru the meridian at Noon In the morning the tracking mirror is on the West side and in the afternoon it is moved to the East side. The tracking motor is turning at 1 rev in 48 hours. The system is aligned North/South with the eyepiece located at the northern end and polar axis of the tracking mirror is polar aligned.
You said the motors work. Are they DC or AC ? If AC are they for 60HZ and 120 Volts operation ?
Posted 19 September 2012 - 12:22 PM
Very helpful. Thank you! The Coelostat does the ability to move the mirror to the other side to compensate meridian crossing. I suspect the mirrors will easily be 1/10 wave based on what I have seen from Goto in the past. The motors are AC and run on 125v (yes, that is what they say) 60 hz.
I wrote to my contact at Goto last night at 11pm and got an immediate response. They are so awesome! The contact had never seen one of these before. They are looking for a manual. I am also going to see if they have the solar prominence viewer, projection attachment, and my little missing piece.
Posted 19 September 2012 - 01:31 PM
The beauty of this system would be to use it with a modern day H-alpha filter, either Lunt or a Daystar.
If you can find a GOTO prominence viewer, the issue will be the narrow band interference filter since the odds are very good that it will be bad. The technology used to make them back 15 years caused them to have a useful life of no more then 10 years. The good news is that you can get replacements. If you want to build your own, here is a link to instructions for an unit I designed and built. http://www.considine...oski/promscope/
I also understand the GOTO made a solar spectrum projector which projected the solar spectrum onto a screen. That would also be a neat accessory to have.
Posted 19 September 2012 - 04:09 PM
Posted 19 September 2012 - 04:13 PM
Posted 19 September 2012 - 04:59 PM
Since the flats are coated, there is nothing stoping you from using it at night to observe the Moon and the planets since they are on the ecliptic as well as the Sun. Along with viewing the Moon with an eyepiece it will also project onto the screen pretty well especially when it is near full. You can also look at a bright star at high mag. and see how round it is, since that is great test of the quality of the flats.
Posted 19 September 2012 - 05:24 PM
I'm not sure there would be a benefit for the intended solar use but is the lens cell marked semi-apo? The OTA and focuser look identical to my 80mm fl 1000mm Goto semi-apo
Posted 20 September 2012 - 12:47 AM
I do intend to try it out on the moon and planets. Thanks for the tip about checking the flats. I will try it on a star, and then on the moon this weekend.
Rob, the scope is an achromat. Not a semi apo .