Crux 1679

[Robert9 (Robert)]

I have just been reading in the current edition of AS&T that in 1679, the french Astronomer Augustin Royer, formally split Crux from Centaurus. In 1679 ACrux sat at a declination of -61deg. (currently -63deg.) thus the furthest north on Earth, one could see Crux just sitting on the southern horizon would be 29deg. For a french astronomer to see this constellation he/she would have to travel due south until arriving somewhere in the middle of Libya or Algeria, or some other country sitting on this latitude.
Does anyone have any information on how/where Royer got to see Crux, or have I got my calculations wrong?
Robert

[sheeny (Al)]

I'd say your calcs are right.

According to this:

http://en.wikipedia.org/wiki/Augustin_Royer

Augustin Royer published a star atlas in 1679 but Crux existed prior to that.

See also here:

http://en.wikipedia.org/wiki/Petrus_Plancius

Al.

[Robert9 (Robert)]

Thanks Al,
Your second link suggests that the observations were in fact made by the Dutch on their voyages to East India. Perhaps Royer just re-worked their sky-maps.
Interesting too that the article suggests that the ancient Greeks also knew Crux, but going back a couple of thousands years Crux may well have been visible further north. I'll check it out.
Robert

[Enchilada]

See my slightly older version article ...
History
http://au.geocities.com/ariane2au/PageSCross002.htm

For visibility, see;
http://au.geocities.com/ariane2au/PageSCross004.htm

and specifically;
http://au.geocities.com/ariane2au/PageSCross005.htm
(Changes by proper motion overtime).

Hope it helps...

[Robert9 (Robert)]

Enchilada, those sites are excellent. Many thanks. I was interested to read the conclusions and references and did try to access Page 7, but the link sent me to page 5.
In regard to the article in AS&T, it appears that Royer was in fact also a sailor and could indeed have both seen and mapped Crux.
All very interesting. Ta muchly,
Robert

[Enchilada]

Originally Posted by Robert9

I have just been reading in the current edition of AS&T that in 1679, the french Astronomer Augustin Royer, formally split Crux from Centaurus.

Robert, who ACTUALLY wrote this in A&ST, please?

I forgot too. Read my very relevant on-line article on this subject;
I think this is absolutely wrong.
"Greek Letter Designations of Southern Stars".

IMO. The Cross as a separate constellation at least 200 years before this!!
If you were to say who the first to list the stars as a separate constellation, I would say it was Nicolas Louis de Lacaillé 1751-52 - but officially it was the IAU in 1930.

See translation "Délimitation Scientifique Des Constellations (Tables et Charts)".

[Robert9 (Robert)]

Andrew, the article was written by the magazine editor, Greg Bryant, with whom it appears, you have had previous, dare I say, literary battles.

I accept your response as to Lacaillé being the first who separated Crux. My original question though was from where was the astronomer observing. Was Lacaillé also a sailor as was Royer?

I was also a little puzzled by the following in your article:
I N T R O D U C T I O N

This now severely modified article was first published in 1998 as a response to an article in the Journal “Universe” of the Astronomical Society of New South Wales Inc. written by Greg Bryant entitled “Stars of the Southern Cross”; Universe, 45, 7 August (1998). Although the original article points out the lack of Greek lettered stars in the constellation of Crux, .........

I recall as a 10 y.o. Cub Scout (1949), that we had to learn about the Southern Cross and we gave Greek alphabet symbols to the stars, particularly remembering how the stars were labelled starting at he bottom with alpha and going clockwise to the little star called Epsilon.

So when were the stars forming Crux assigned their current letters? It appears from your other articles that a few hundred years ago they had Greek letters only were assigned differently. I think I'm now getting a little confused.

Robert

[Enchilada]

Originally Posted by Robert9

Andrew, the article was written by the magazine editor, Greg Bryant, with whom it appears, you have had previous, dare I say, literary battles.

Thanks. I now see the origin of the problem here. Mr. Bryant has made this very same error before. Again he has not gone into the detailed research, as the role of Royer has been perpetuated since Englishman Basil Brown in 1932 ("Astronomical Atlases, Maps and Charts. Pub. Search Publishing (London)" boldly claimed the origin of Crux (actually Crux Australis) was Royer. This is wrong, as there are several source going back into the 13th Century. (English literary sources have traditionally poo-pooed French claims to anything, and many source show significant bias!! (As do French sources - think of the discovery of Neptune, for example.)) It was probably the Spanish in South America!

Originally Posted by Robert9

I accept your response as to Lacaillé being the first who separated Crux. My original question though was from where was the astronomer observing. Was Lacaillé also a sailor as was Royer?

Royer did not leave France as far as I know, and adapted four celestial maps in 1679 as "Cartes du Ciel Réduites en Quare Tables, Contentes les Constellations" (I saw Map Two in 1998 at a London exhibition in the National Library there.)
He actually never observed Crux at all, and very probably adapted it from a map produced earlier by Edmond Halley from St. Helena in 1669. (who made observations of southern stars mainly to compare these to Ptolemy's positions.) This was published in the same year in London.
Abbe Nicolas Louis de La Caillé (Lacaillé) observed from the Cape of Good Hope using 12mm refractor making a detail southern sky atlas. Lacaillé set most of the order of the Greek letters for the modern southern constellation.

Originally Posted by Robert9

I was also a little puzzled by the following in your article:
I N T R O D U C T I O N

This now severely modified article was first published in 1998 as a response to an article in the Journal “Universe” of the Astronomical Society of New South Wales Inc. written by Greg Bryant entitled “Stars of the Southern Cross”; Universe, 45, 7 August (1998). Although the original article points out the lack of Greek lettered stars in the constellation of Crux, .........

The lack of Greek letters refers to Mr. Bryant's contention of why the Greek letter stopped at mu, and did not continue to omega.

Originally Posted by Robert9

I recall as a 10 y.o. Cub Scout (1949), that we had to learn about the Southern Cross and we gave Greek alphabet symbols to the stars, particularly remembering how the stars were labelled starting at he bottom with alpha and going clockwise to the little star called Epsilon.

So when were the stars forming Crux assigned their current letters? It appears from your other articles that a few hundred years ago they had Greek letters only were assigned differently. I think I'm now getting a little confused.

Greek letter we assigned to stars first by Ptolemy/ (Hipparcos?), a practice used in the northern skies. They also labelled them by features within the constellation - the Crux stars as horse parts, like "Quae ion extremo anterioris dextri pedis" (Alpha cru) or "Quae est in talo ejusdem pedis" (Beta Cru).

In those days, designations appear with the stars within the then 48 constellation. Centaurus was one of them, with Crux being part of Centaurus - an asterism per se.
In fact Bayer draws Crux over the Centaurus stars, but labels then zeta, xi, epsilon and upsilon Centauri (now discarded). Royer allegedly labelled them alpha through zeta, using Halley's brightness in his observations. Neither the order here is used nor some of the assignments match today's I.e. iota Cru is wrong

So when were the stars forming Crux assigned their current letters?

Lacaillé 1751-52

Thanks for your relentless critical quizzing! Useful feedback, Robert! I will update my own article accordingly.

[Enchilada]

Below is a further discussion on Crux before Royer, which is part of a booklet I've been working on for a while. This might give a better perspective to the question here...

******************

A recent found image of the Cross appear on a celestial globe that was engraved by Jodocus Hondius and created from drawings by M. Emerie Mollineux (Molyneux) of Lambeth in 1592 in Tudor England, whose new constellation name was then adopted by Bayer in 1603. This clearly precedes Royer claim. By since this time the stellar name of Crux has been found in several earlier historical references. One of the earliest significant known sources is from a private letter written in 1503 by the Italian navigator, Amerigo Vespucci, who described "four magnificent stars" Another by the sailor Antonio Pigafetta in 1515 said while travelling of the Globe, wrote;

“...a wonderful cross, most glorious of all the constellations in the Heavens.”

Modern historians have more recently have assigned Crux's original derivation to the Italian, Andrea Corsali that was found in an old twenty-page letter and manuscript entitled; "Lettera di Andrea Cosali allo illustrissomo Principe Duca de Medici, venuta Dellindis del mese di October nel XDXVI"; (The original of can be found in the National Library of Australia and is available in the Internet accessible Archives Section.) Here we can clearly see the small drawn figure on the first written page of the manuscript clearly showing Crux and its five principal stars near the zenith, but also seen are the two Small and Large Magellanic Clouds and the position of the South Celestial Pole (polo anlatico). The whole page can be viewed by selecting the thumbnail mentioned in the page above. It seems this document is yet to be properly translated. Corsali wrote in 1516 that Crux was;

"...is so fair and beautiful that no other heavenly sign can compare to it."

One of the first instances of the Southern Cross in the historical literature was by Dante's (1265-1321) in the famous trilogy "Paradisio", "Inferno" and "Purgatoio".

Here in the last book, Purgatio, he describes only the four principle southern stars of the Cross - naming them after the admirable virtues of Justice, Prudence, Temperance and Fortitude. Dante seems once to have seen the Cross low on the southern horizon and likely missed faint Epsilon Crucis in haze or poor seeing.

Yet of all of these claims it remains quite uncertain if these individuals had any influence with its popularist name of today. In my own opinion the true derivation of Crux's name and origin will likely to remain forever unknown to us.

[Robert9 (Robert)]

Andrew,

Thank you for your interesting and exceptionally detailed reply. It is quite obviously a study of much passion. What started as an innocent question from my wife at breakfast when I showed her the article, has ended up as a fascinating lesson in astronomy history.



Robert

[sheeny (Al)]

I second that.

Thanks for an interesting dialogue!

Al.

[Wavytone]

Another reference to an atlas from 1594 showing Crux as a separate constellation (top of p. 216)
http://articles.adsabs.harvard.edu/f...00215.000.html

and the Hondius globe of 1600 is mentioned on page 219

[Enchilada]

Originally Posted by Wavytone

Another reference to an atlas from 1594 showing Crux as a separate constellation (top of p. 216)
http://articles.adsabs.harvard.edu/f...00215.000.html

and the Hondius globe of 1600 is mentioned on page 219

Thanks Wavytone.
More 'classically' definitive was E.B. Knobel's "On Frederick de Houtman's catalogue of southern stars, and the origin of the southern constellations"
MNRAS., 77, 414-432 ( See http://adsabs.harvard.edu/abs/1917MNRAS..77..414K )

The central source of some modern data and historically discussion, here.

Crux's origin, however, probably even predates de Houtman's works !!

Make a better future AS&T article methinks than the current one first described here !!

(What do you reckon Greg Bryant? Happy to write it for the magazine if you want me too.)

[Wavytone]

If you want to try a long shot it's even possible Crux appears in Ptolemy's list of bright stars, I'd look except I've loaned my copy to someone for a while and it's not in ADS.

[Enchilada]

Originally Posted by Wavytone

If you want to try a long shot it's even possible Crux appears in Ptolemy's list of bright stars, I'd look except I've loaned my copy to someone for a while and it's not in ADS.

Descriptions
Ptolemy Name
No No Description
965 31. Quae est in poplite pedis dextri...... gamma Cru
966 32. Quae est in talo ejusdem pedis........ beta Cru
967 33. Quae sub poplite sinistri pedis...... delta Cru
968 34. Quae in sura ejusdem pedis............ alpha Cru
969 35. Quae ion extremo anterioris dextri pedis...... alpha Cen
970 36. Quae in genu sinistri pedis........... beta Cen
971 37. Quae est extra sub dextro posteriore mu Cru

Current Data
Ptolemy Name
No No Long Lat m V R.A. 1900.0 Dec. PMRA PMDec No.
965 190 00 -51 10 2 +1.63 12 25 37.0 -56 33 12 +0.029 -0.267 4763 gamma Cru
966 195 20 -51 40 2 +1.25 12 41 52.5 -59 08 31 -0.038 -0.017 4853 beta Cru
967 186 20 -55 10 4 +2.80 12 09 49.9 -58 11 33 -0.038 -0.010 4656 delta Cru
968 191 10 -55 20 2 +0.79 12 21 02.2 -62 32 42 -0.027 -0.015 4730/1 alpha Cru
969 218 20*-44 10 1 -0.29 14 32 48.3 -60 25 22 -3.608 +0.712 5459/0 alpha Cen
970 204 10 -45 20 2 +0.61 13 56 45.8 -59 53 26 -0.020 -0.023 5267 beta Cen
971 194 40 -49 10 4 +3.70 12 48 43.4 -56 37 48 -0.030 -0.008 4898/9 mu Cru

[Enchilada]

Originally Posted by Enchilada

Thanks. I now see the origin of the problem here. Mr. Bryant has made this very same error before. Again he has not gone into the detailed research, as the role of Royer has been perpetuated since Englishman Basil Brown in 1932 ("Astronomical Atlases, Maps and Charts. Pub. Search Publishing (London)" boldly claimed the origin of Crux (actually Crux Australis) was Royer.

I've recently read Greg's article in question appearing in the current issue of AS&T. Considering the single page article, I would honestly now concede his comment was reasonable in its context. If any slight criticism were to be made, then the words "probably" or "likely" would have been preferable rather than speaking in absolute terms.
The true origin of the constellation of Crux is certainly an interesting one, and its debate will likely continue into the future. At least here, southern hemisphere knowledge is important to spread the word. Greg Bryant, overall, does a pretty good job in AS&T doing this kind of general education. I'd encourage him to do more...

[Robert9 (Robert)]

Thanks for the post script Andrew.

Robert