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[OM] Astrofest

Subject: [OM] Astrofest
From: "Terry and Tracey" <foxcroft@xxxxxxxxxxxxxxxxxxxxxx>
Date: Tue, 9 Nov 1999 20:18:23 +1100
The eldest some (aged 7 Kyle) and I went to an astronomy festival at
Coonabarabran last weekend. I'll start with some photography stuff, then
astro stuff, so delete as appropriate.

Some of you may have seen the excellent deep sky photos made by David Malin.
He takes 3 photos for each one, using 10" or 14" square glass plates,
depending upon the telescope.

First he takes an exposure with a blue filter, then a new plate with a green
filter, then a new plate with a red filter. The plates are black and white.
Then he copies the plate to negative emulsion (probably a positive if I
think about it. He just said a film emulsion), and prints them by putting
blue light through the blue negative, then putting in the green negative
with genn light onto the same paper, then red. The results are fantanstic.
The human eye will interpret all low light levels as black and white, and
film colour response is different to the eyes, so this is the only way to
see what the colours really are.

Unfortunately, Kodak will no longer make the photo plates he needs. He is
the only person on earth using this type of plate, and Kodak have kept the
stuff availalbe as a support to the scientific community. But it's time is
up. So he is going to CCD. I asked him if the quality was as good, he said
nearly.

But lets put this in perspective. He uses a 5" square CCD array with 64
million pixels. And 320 Mb per exposure. A different league to us I think.
He showed some results, but they weren't as good as the film. He said he was
not yet happy with them, and will work at them some more. Still, the
available image is smaller by 1/4 at least.

Astronomy stuff. It rained. We were in the Kombi, and I ws about to go get
two of every animal. Glad I didn't, I had enough trouble cleaning it as it
was. It finally cleared and we sussed out some stars. I was amazed at how
much more light a 8" Newtonian let in than an 8" Cassegrain. Kyle went off,
looking at clusters and galaxies. I can't shut him up now. We need a new
scope. Maybe I can sell some children.....

The next day was fine, with some good stuff. There was a talk in the evening
on gamma ray bursts, red giant, neutron stars and black holes. Great. Before
Kyle would ask "Mum, which planet's moon spins in a retrograde motion?"
(that Magic school bus CD is to blame) I'm glad he asked Mum. Now it's all
about "When will Bettlegueuse form a neutron star?" Great. Kids. ;-)

One bloke put a CCTV chip in a 35mm film container, put it in his eyepiece,
and recorded things on video. Only 500 lines resolution (or whatever PAL
is), but it only cost $100 all up.

Anyway, I've got to sell stuff to get a scope now.

Foxy


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