I've been in New Zealand for a week now, staying in the town of Alexandra in the Central Otago district, South Island. I've been very warmly hosted by the Central Otago Astronomers (CAO), who have a rather unique observatory located at the local (very little used) airport.
The observatory was originally built by a gentleman named Graeme Long, who lived 20 or so miles from Alexandra. Unfortunately, he died before the telescope was ocmplete. The CAO purchased the observatory and telescope from his estate with a grant of public funds for NZ$7,000. The observatory contains a 21" f/5 Newtonian reflector.
The observatory building is made of corrugated metal on a wood frame sunk in a concrete base. The building is about 15' x 15' x 20' high. It sits on 4 casters which run along a circular rail. There is a retractable slit in the roof. The entire building must be rotated to point the telescope, using a metal pipe about 3.5" in diameter as a lever. In the center of the building is a (fixed) concrete tube about 18" in diameter and about 12 feet long sunk into the ground; about 18" protrudes. The building rotates around the tube, in which the massive telescope mount is set. The bearings are massive, there's no counterweight, and the steel fork arms are huge. The telescope sits is a box frame to allow the telescope tube to be rotated. There is a remp running around the inside of the building, about 7 or 8 feet high, with stairs and a small observation area.
My primary contact, Alan Thomas, has told me that they could only view a few objects each night; I now understand why.
There is a drive for tracking. The 21" mirror was coated in Australia, and is quite thin, maybe an inch to an inch and a half. I'd say it's good to about 1/4 to 1/6 wave, judging from medium power views.
Friday night, I checked the collimation with my holographic laser collimator, and found the telescope was badly out of collimation. Saturday night, several of the astromoners gethered to collimate the telescope. First, I centered the secondary, then centered the holographic pattern on the primary with the (4) adjusting screws on the secondary holder (much easier with three screws, I believe) and finally adjusted the primary using the collimation bolts. The best we could do was to get the return red dot about 2 millimeters from the laser exit.
Last night, Alan came out at about 1:30 a.m., when the sky had cleared - I was waiting at the airport for this to happen - and we viewed the Tarantula Nebula. Alan said that the images were much improved. They only have some 1.25" eyepieces (Plossls or Vixen Lanthanums) so I bought over my 13mm Nagler. Detail was quite impressive. I tried a 19mm Russell, and again, the image was excellent. But when I tried to use my 30mm Widescan II, it had dewed up as it was in the focuser of my 13". By this time, Alan had to leave as he had to work the next morning. I stayed for another hour, but packed up at 4 as my car windows had frosted over and my secondary had dewed up. Of course when I got to my motel at 4:30 the sky had turned crystal clear...
I have some photos of the observatory and telescope - and plan to take some more.
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|---|---|
| 1 | First Exposure |
| 2 | First Light |
| 3 | Unique Observtory in New Zealand and Collimating the 21" |
| 4 | Observations 5/22 |
| 5 | Observations 5/23 |
| 6 | Observations 5/24 |