Presentation to visually impaired would-be astronomers.

> is that presentation available or do you have a short summary you
> could post?

It wasn't a really formal presentation, but here's a summary:

My 'audience' were folks attending the 2009 achromatopsia convention. This is a serious and very disabling (but little known) eye condition which causes day blindness, poor visual acuity uncorrectable with glasses, and complete (or nearly complete) lack of color vision. No treatment is available.

First I talked about how telescopes work and explained that when it came to absolute angular resolution, it is the size of the main optical element, not the user's visual acuity, that determines the finest detail visible. I also mentioned the intrinsic limitations of atmospheric seeing. All this came as a surprise to people.

I encouraged my audience NOT to get binoculars contrary to the usual advice to beginners. This is because binoculars simply do not provide enough magnification (only 7x, 10x, etc) to be of much use for astronomy for the visually impaired. Instead I recommended they start with a decent telescope on a good steady mount with slow motion controls.

Then I handed around the S&T pocket sky atlas. They leafed thru it with wonder, having never realized the sky was so rich with items to see.

Next I discussed the sort of objects that could be viewed and the approaches to use given the nature of the disability. For example, I mentioned that they should have no more difficulty in seeing galaxies and nebulae than anyone with normal vision -- but that everyone needed a dark enough sky to really get a good look at those! For other things like the planets, double stars, and moon craters, I suggested using high enough magnification (i.e. 400x, 500x or even 1000x if needed) to be able to actually see and get a good look at the item of interest. Here I again noted the importance of a steady mount preferably with a clock drive for this sort of thing. I had to admit that most would not be able to see any color (star colors, contrasting double stars, blue nebulas, colors of features on planets, etc.) in astronomical objects. Another astronomer present -- who has normal eyesight -- graciously assured people that the colors of these items were for the most part unexciting
 and that they weren't missing out too much in not being able to see them.

Of course, no introductory astronomy presentation can be complete without a discussion of light pollution!! Besides the issue of sky glow, I pointed out how unshielded lights are especially glary and bothersome for people with achromatopsia, for whom nighttime is when they can otherwise see best. I taught everyone the basic ways to help reduce light pollution at their homes and businesses and encouraged them all to spread the word and get involved in light pollution reduction politics.

Next it was time to see some actual stars. :-) We strolled down the street from the hotel. There I pointed out the summer triangle and a couple people were even able to spot gamma Cygni - no mean feat through humid downtown Chicago light pollution. I also had them try to see and split epsilon Lyrae (the main pair, 3.5' apart, not the two close pairs!) using my 8x21 binoculars -- some could, some not. It was difficult since Lyra was near zenith at the time.

Then we strolled down along the river and I showed them Jupiter. I had hoped at least Callisto at 12' separation would be visible to everyone with the 8x binoculars but alas it was not. The sky glow was just too thick or binoculars not powerful enough. Even so, they had no idea that Jupiter itself was so bright and visible and were mightily impressed. (this was Aug. 13 - the night before opposition)

Unfortunately I don't yet have a really portable travel telescope, only my grab and go binoculars. I promised everyone at the next national achromatopsia convention I would definitely bring a telescope and show them much more!

-DG

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