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Dear Fank,
You wrote:

> Assuming that the 'Frank' you reference in your comment is me, I'll say that 
this doesn't sound like something I have said! No worries if you're 
remembering 
> someone else. I just want to clarify that I don't think that was me. :) In 
fact, star-to-star distances can be used to test arc error, but lunars are 
better. And I agree 
> with Modris Fersters that, with some effort and repetition and, of course, 
care in observation, a fairly good sextant calibration can be re-created 
using home 
> observations.

I meant you, of course, but if you did not write this, I apologize. Perhaps 
someone else wrote this, or I read this in some book.
This was very long ago, probably more than 20 years ago, when I was trying to 
test my new SNO-T with star-to star distances, and
we discussed this on the list.

I agree that Lunars, especially daytime Lunars are be a better way to test the 
error than star distances (and I did this as well).

> Maybe it's just a matter of "degree" (or actually seconds) that we're 
talking about. With lunars, a reasonable expectation of home certification 
would be +/-0.2' 
> which of course is +/-12 seconds of arc. 

I am a bit more pessimistic on that, but anyway I did not mean sextants with 2 
minutes arc error. There is no doubt that errors of 0.3'-0.5' can
be reliably detected by repeated careful observations of Sun-to-Moon distances.

Alex.

  

   

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