Almagest study

[Guest guest]

Julia wrote:

 

" Taking a moment to post, as I've just completed setup on an

Excel sheet to plot sidereal longitudes and latitues for all

1026 unique stars catalogued in Ptolemy's " Almagest " and

computing position errors for various epochs, enabling many

kinds of tests. I can use the date of the whole catalogue or

select stars for different criteria of precision in

positioning them. "

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has been having problems of late so that sometimes a message appears

multiple times in mailboxes, and some messages simply disappear. Julia,

your message was one that never made its way to my mailbox, so I saw it

accidentally only this evening (December 4), and copied it to my mail program.

 

You wrote:

" ...As error tolerance is reduced by the trade-off of discarding

progressively more data, that reference date slides forward

within the same decade, but 52 - 54 CE looks fairly

reasonable, consistent with his placement of Aldebaran and

Antares at 12º40' of their respective signs, rather than the

15º typically cited.

 

" Ernie Wright developed a nice little graphic freeware

program called " Almagest Stars " , which incorporates some of

Grasshoff's work ... I'm hoping to acquire the text you

mentioned... "

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I think you'll want that book, Julia, for the work you're doing. If you

can't find a copy, perhaps I can lend you mine. I bought the book in

Berkeley, CA, some years ago. Pricy: reduced from $74 to $50. I think I

must have bought it for the star tables which list all of Ptolemy's stars

and compares them to true positions in -128. All Ptolemy's errors are

listed. Grasshoff notes:

 

" Because of the systematic error in longitude along with the possible older

origin of the Almagest coordinates, the positions of the stars are not

recalculated for the epoch of Ptolemy (+137), but rather for the epoch

-128. (The year of many Hipparchan observations reported in the Almagest)

 

You wrote:

" It's just a delight working with the data, even

if I don't get around to doing everything I'd like. At least

it's a handy list of so many noteworthy stars, about 400 of

which have been named by various cultures over time... "

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This is pure Mercury, so certainly reflects Mercury dasa. And wonderful

retirement is following.

 

Blessings,

Therese