NavList:

Alex wrote:
"What is the difference between  this collimation test and the
ordinary one recommended on the book:
"look  at some remote object, first over the sighting vanes
(=Celestaire cylinders)  and then through the telescope.
What is the advantage of the laser beam spot  here?
Why not a remote wire instead."

It's easier and more accurate  though there are plenty of ways to do it with
traditional equipment that will  make the trick more accurate. For example,
when I originally wrote this up on  the list about nine months ago, I suggested
placing a small telescope with  crosshairs on the sighting vanes or Celestaire
cylinders. Then you sight through  the telescope and identify the spot on the
wall that is centered in the  telescope. Maybe you get an assistant to mark
that spot with an "X". Then you  look through the sextant telescope and see if
it's off-center. Using a laser  automatically draws that "X" on the wall. It's
not a big  advantage.

And:
"Another question: Can you (or anyone) tell  me,
which scope of which sextant,
except the astronomical scope of  SNO)
has a collimation adjustment?

I have NEVER seen such scope,  neither on e-bay nor in
the antique shops, not in the catalogs of  modern
production."

You probably have seen them, but not on newer  sextants. I would say that any
sextant manufactured after about 1970 is  collimated by design. If
manufacturing standards are high enough, there is no  reason to adjust sextant
collimation. On the other hand, the majority of  professional sextants I've seen from
before 1970 or so have small adjustment  screws which permit telescope
collimation.

-FER
42.0N 87.7W, or 41.4N  72.1W.
www.HistoricalAtlas.com/lunars 


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