Thread: list of 173 'navigational' stars?
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John Nagelson John Nagelson is offline
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First recorded activity by BoatBanter: Apr 2007
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Default list of 173 'navigational' stars?
On Apr 9, 7:30 am, (Eugene Griessel) wrote:
"John Nagelson" wrote:

Does the ordering in the Nautical Almanac have a name?
I mean with Sirius at no.18, etc.
And could someone please enlighten me on the origin of the numbering.

Many thanks.

Look up the life of John Flamsteed, Astronomer Royal.

If I might answer my own question (!)...
The Nautical Almanac numbers the 57 navigational stars
simply in decreasing order of SHA.

Thus number 1 is Alpheratz, SHA 358 deg
number 2 is Ankaa, SHA 354 deg...
number 18 is Sirius, SHA 259 deg...
number 57 is Markab, SHA 14 deg

I should have spotted this!

Flamsteed numbered stars within each constellation,
in increasing order of RA, e.g. Sirius is 9 Canis Majoris.
With some the Flamsteed numbering is now out of sync though.

No such problem with the 57.
I wonder what system was used for numbering the others that make
up the Nautical Almanac 173.

John

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