I tried to send the following message with a 40K diagram attached but it bounced, so I'm re-sending it without the diagram. I thought the limit was 50K? Brad
On Wed, Jan 26, 2011 at 4:54 PM, Brad Lufkin <[email protected]>wrote: > Here's a diagram of an orthographic projection centered at Rio at the time > in question. It's clear that this diagram does not match the flag of Brazil. > While the north-south arm of Crux is indeed at the longitude of Rio, the arm > itself can never be truly north-south, as the two stars have slightly > different hour angles. Also, and far more importantly, Crux is too far north > on the flag, being nearly at the same latitude as Rio (the center of the > map). In fact, the declination of Crux is around -60 degrees, whereas Rio, > as we know, is nearly on the Tropic of Capricorn. > To find Crux in the diagram, look about two-thirds of the way down. It's > the constellation containing Mimosa. > I can't think of any projection, other than an artistic one, that would put > the stars in these relative positions. > Brad > > > On Wed, Jan 26, 2011 at 2:11 PM, James E. Morrison < > [email protected]> wrote: > >> Frank, >> >> It would take some effort to make a conclusive argument as to the >> projection used on Brazil's flag, but the description on Widipedia says it >> is an orthographic projection (the projection origin is at infinity). The >> date and time when Crux (the Southern Cross) was on the meridian are correct >> in the Widipedia article. I'll look at in more detail as time permits. >> >> Best regards, >> >> Jim >> >> James E. Morrison >> [email protected] >> Astrolabe web site at http://astrolabes.org >> >> Jan 26, 2011 05:21:44 AM, [email protected] wrote: >> >> Dear Roger (with a question for James Morrison), >> >> You prompt an interesting side-track in your >> observation that... >> >> > The national flag for Brazil also incorporates >> > an armillary sphere... >> >> It seems that you are living just a bit in the past >> here. Aren't we all? The flag of Brazil incorporated >> an armillary sphere until 1816 when it was largely >> covered up and in 1826 it disappeared from the flag >> altogether. See: >> >> http://en.wikipedia.org/wiki/Flag_of_Brazil >> >> This article describes the current flag in great >> detail. It is dominated by a representation of >> the night sky over Rio de Janeiro at 08:37 on >> the morning of 15 November 1889. >> >> In an intriguing note, the article explains that >> the positions of the stars were altered slightly >> in 1992 to account for proper motion since 1889. >> >> The Brazilians are to be commended for their >> insistence on precision but this alteration means >> that the flag no longer represents the night sky >> in November 1889. As such the current flag is >> a bit of an iconoclast. >> >> I do hope that "Instruction on the Design of the >> National Flag" is in the school curriculum in >> Brazil. No wonder the country is doing well! >> >> The only detail that I would like explained is >> just what projection is used. >> >> Can James Morrison comment please? >> >> Frank King >> Cambridge, UK. >> >> --------------------------------------------------- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> --------------------------------------------------- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> >
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