NavList:

Hi Frank,

Thanks for your helpful responses and tips - very much appreciated!

• Holding the sextant like that makes sense, I have given it a try indoors and it seems far more comfortable. While taking the sights I was wondering how much slower lunars change compared to normal altitudes, and after just a little bit of thought I can see why they would change up to 30 times slower, given the rate at which the moon moves across the celestial sphere.
• I can't remember now where I read about 7x scopes being harder to use, it sounded reasonable to me given the notion of a boat pitching and rolling around in a heavy sea. But I understand that you choose your time, weather conditions and sea state to take good sights (and keep your sextant dry). You can tell that I haven't taken any actual sights at sea yet! But I have plenty of sailing lined up over the spring and summer to practice :)
• I will keep a casual eye out for 7x scopes on ebay, but in the meantime thanks for explaining the statistical difference in sight accuracy. I'll aim for the 4 sight average that you said is best.
• Thank you for confirming that I was imagining things, and that the sights will always be the great circle angle. I think for my next attempt, things will be much easier using the different sextant holding technique you mentioned, and then I will be able to line things up in the centre of the field of view and be happy that I've measured the correct distance.
• I didn't know about this view of Stark's tables when I bought them, at the time they were the only method of clearing lunars that I had managed to find during my fledgling research. But now that I know what you've told me, I am indeed much more interested in something historically accurate like Thompson's tables. I have located the Google Books version and am intrigued to give them a try, and as well as that I'd be very keen to sign on to one of your online lunars courses if I can make the dates work.
• Thank you, I didn't realise index error was the most important thing. I believe I have adjusted my index error out with the mirrors, but perhaps I'm not being precise enough. I will probably try the method of bringing the sun's disk to touch from both directions and averaging the results, to see if I can measure the index error to the nearest 0.1'.

Again, thank you very much for all the help, I'm looking forward even more now to my next lunar session!

Jonny