PPT in the News… Again

It was a last minute request. OK, not actually the last minute, but two days is not much lead time to plan a public outreach event.

Fortunately there was not much to arrange, a single solar telescope and the standard table setup we keep packed and ready to go, all we had to do was show up. Drive up to the Pōhakuloa Training Area to join in their Earth Day events. There would be several hundred students from local schools, tables and displays from other organizations, a good outreach opportunity.

Pōhakuloa Solar Telescope
A solar telescope set up at Pōhakuloa Training Area for Earth Day.
In ten years of driving past the front gates of PTA, I had never been inside. Why not, just an easy drive from Waikoloa, and I have a telescope that will do the job perfectly.

It seems odd that a military base would celebrate Earth Day. What do attack helicopters, live munitions, and troops have to do with the environment? The answer should not be that surprising… Military bases are often large effective nature reserves.

Large areas of land, much of which sits unused and undisturbed, are closed to public access. An active range needs huge safety and buffer zones around the firing ranges. Of the 133,000 acres that makes up PTA, only a small percentage is directly impacted by the training activities. The rest is home to a endemic and endangered species, closed to any activity that can disturb the land.

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The Purple Refractor

Apparently the purple refractor was quite the hit on yesterday’s webcast. Not only did it provide beautiful imagery of the Transit of Venus for everyone to enjoy, but caught the attention of many viewers. There we many comments… “Where can I get one?”, “How much?”, and my favorite… “…paint Keck purple!”

Violet Haze really is a great telescope, an entirely hand-made instrument, with the exception of the focuser. The lens set is a full apochromatic triplet by Roger Ceragioli, a true expert in refractor design and manufacture. The purple optical tube is my own machine work. The result is a truly unique telescope that is a joy to use.

Imaging Venus in the Daytime
Imaging Venus in the daytime a mere 12°44' from the Sun.

Violet Haze, A 90mm f/13 Apochromat

Violet Haze
Violet Haze, a 90mm f/13 apochromatic telescope
I had wanted a high quality APO refractor for some time. Mostly for photographic use. Opportunity presented itself when Roger Ceragioli offered me a 90mm telescope he had finished the year before and was willing to sell. Working for the Steward Mirror Lab, Roger normally grinds very large optics, things like secondaries for six to eight meter telescopes. But as a hobby he makes somewhat smaller telescopes. This particular lens set had won him a merit award at RTMC in 2002. I had previously seen this telescope and after some negotiation we settled on a price.

The lens triplet is exquisite, providing absolutely perfect airy disks at high power. The photo below shows an example of the out of focus image of Antares taken with the telescope. Pulling out my copy of Suiter’s Star Testing Astronomical Telescopes shows nearly identical images for the ideal diffraction pattern. No wonder the ‘scope won a RTMC merit award.

Photographically it has proven to be almost perfectly free of color, corrected across the spectrum. There do not seem to be any detectable UV or IR halos around bright stars. This is partly a result of good design, and aided by the long focal length of f/13. No field flattener is required, with pinpoint stars across the focal plane.

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