NavList:

Bob B., in your post on Sept 3 you describe seeing Venn-like images of the sun when viewing through the horizon mirror to measure the lunar distance. You were asking if I was experiencing the same phenomenom with my Davis 25. I'm not sure what I was seeing. First off, when shooting a lunar, I view the sun through the index mirror with all 4 shades deployed and I have an additional shade made from disposable dark glasses I was given after a dilated eye exam that is double-stick taped to the front of the shade stack. I also was wearing sunglasses (medium tinted I would say). With these 6 shades in place, the disc of the sun was very sharp and comfortable to look at. I don't deploy any of the horizon shades so as to get the brightest image of the moon (sun glasses on still). To look at the sun through the horizon mirror I deploy the 3 shades in front of the horizon mirror in addition to the taped-on shade described previously and my sun glasses. The sun was quite bright and the best I can describe the image of the sun is that there was a little rim of green beneath the sun and a red rim above. I'm not sure if this was glare due to the brightness of the image or something to do with refraction of different wave lengths of light or imperfections in the plastic lenses in the telescope or not viewing through the center of the lenses. Anyway, that was what I saw. Maybe others would know what was causing the image you saw.

Yesterday , today and for the next 2-3 days, lunars will be "near limb". Beyond that, only a small portion of the moon will be illuminated by the sun, making it hard to do a lunar. I shot a single lunar today and my error, according to Frank's app, was -1.2'. Just lucky.

I, too, am not clear on how to get a lonigitude after having determined GMT from a lunar distance measurement. Frank gave a clue at the end of the Lunars class but it passed me by. I'll have to work on it.

Homer