Les Dalrymple
Contributing Editor:
Sky & Telescope Magazine and
Oz Sky & Telescope

(18" Discovery mirror)

First light was at two successive 'Open Nights' at Sydney Observatory last Friday and Saturday night when we had over 400 members of the public through each evening.
 
Installation was straightforward -- the telescope had to be lengthened about 15mm which was fairly easy to accomplish by fabricating some new, slightly longer joining brackets at the top end which join the top girder to the truss poles -- very straight forward.  Checked the mirror at effectively F 9.6 using a barlowed 'easytester' (null ronchi) on Spica  -  5 ruler-straight evenly spaced lines .  Star test at x317 with a 7mm T1 Nagler -- can't see anything wrong at all -- No sign of any errors.
 
On Friday night open night, I spent the first couple of hours on a couple of open clusters around Crux/Eta Carinae.  At 8.30pm I swapped to Jupiter and popped a 12mm T2 Nagler in for x185. After focusing (admittedly the seeing was unusually good for inner Sydney -- we overlook the Harbour). The view was simply unforgetable. I watched a transit of Europa I think (piecemeal - in between members of the public), where I could see the bright disc of of the Moon crossing the whole of the planet, followed 1/2 hour later by the shadow. All four Moons were distinguishable and identifiable by sizes of the disc and colour.
 
A nearby (only 10m -- no seeing excuses here) 8" LX200 had trouble detecting the shadow of Europa believe it or not.  The swirls, knots, ropey stuff and brownish blobs in the southern and northern polar areas were too bizzare and detailed to describle, plus the detail following the GRS within the SEB looked like a Voyager pic.
 
After just 10 mins on Jupiter (enough time for word to get around) I had a queue of 60 - 70 members of the public behind me.  Almost everyone, once they looked, said words to the effect "I just spent an hour in a queue to see Jupiter upstairs (16" LX200 GPS in the main dome) and it is nothing at all like this -- this is AWESOME".  There were gasps of astonishment galore. 
 
At the end of the night (11pm), I and the other guides had a 20 minute Jupiter drool fest with a 9mm T1 Nagler at x247.  Two other guides asked "Can you build another one -- just like this one for me?"
 
Just thought you'd like to know it all worked out well.
 
Can't wait for that blasted Moon to get out of the way now!!
 
Seriously, one or two two of my fellow guides at the Obs (both amateurs) have said that they are "hooked" and will approach you for a mirror (Gary Mitchell -- my observing buddy and fellow telescope builder -- and I will probably build the 'scopes when the time comes)  -- you get my recommendation without hesitation. 
 
Thanks for a great service.
 
 

David purchased a Discovery 6" primary mirror for his "homemade strut type" telescope.

"Tested it tonight on Saturn... beat the pants off my 4" APO... Cassini division all the way around with surface showing cloud bands!!!

"Best optics I have ever owned (including an 8" and 9.25" Cat)."

J. M. from San Diego, CA - Designed and built his trussed, alt-azimuth telescope and installed a Discovery 24", f/4.5 primary mirror and diagonal.

"...and the compliments from the awesome views just keep coming."

"I have to hand it to you guys, you always deliver for me."

K. Merkley, 17.5" Truss Design (first light)

Starting with the Andromeda Galaxy... I turned the focus knob and that fuzzy patch came into view. Geeez, I thought it would be brighter, bigger and better than the view in my 10" Dob but it wasn't. Then I moved the scope slightly and saw the glow of M31. I was initially viewing one of the 2 companion galaxies and didn't know it.The views were breathtaking..."