1 Aapril 2009

The first of April, some do say, Is set apart for All Fools' Day. But why the people call it so Nor I, nor they themselves do know. Anonymous

When you read the books they tell you that the Bayer designations for the stars of a constellation are assigned in descending order of magnitude with α being assigned to the brightest star, the lucida, β to the next brightest, γ to the third brightest and so on. This is illustrated by the constellation Ursa Minor:

Bayer	Proper Name	Mag.
α	Polaris	2.02
β	Kocab	2.08
γ	Pherkad	3.05

But my experience in documenting my observations and in creating my own naked-eye star atlas is that this is rarely the case. A case in point is Gemini:

Bayer	Proper Name	Mag.
β	Pollux	1.14
γ	Alhena	1.93
α	Castor	1.98

So I decided to use the Cambridge Photographic Star Atlas to validate my observations.

The first thing I found was that most of the literature only lists the brightest stars in any constellation down to mag. 4. So sometimes only the lucida is listed and 12 constellations don't have any stars bright enough for even the lucida to be listed. I had to go to the Web to flesh out my data since I wanted to determine the order of Bayer designations for the three brightest stars.

My quickly formed impression was that modern constellations were more likely to follow the rule than were ancient constellations so I soreted the constellations and compiled statistics that way as well as en toto.

Constellation	Order of Brightest Stars	Number	Percent
All	α	56	64%
	α and β	41	47%
	α β and γ	15	17%
	lucida other than α	32	36%
Ancient	α	26	57%
	α and β	20	43%
	α, β and γ	6	13%
	lucida other than α	20	43%
Modern	α	30	71%
	α and β	21	50%
	α, β and γ	9	21%
	lucida other than αr	12	29%

As long as I had the data in Excel I sorted it by the magnitude of the lucida to see how many constellations are of each order.

Lucida	Number	Percent
brighter than 0 order	4	5%
of the 0 order	8	9%
of the 1st order	13	15%
of the 2nd order	25	28%
of the 3rd order	26	30%
of the 4th order	11	13%
of the 5th order	1	1%

The faintest constellation is Mensa with a lucida of only mag. 5.1.
The lucida of Leo Minor doesn't even rate a Bayer designation although it does have a propper name.

Bayer	Proper Name	Mag.
46 LMi	Praecipea	3.83

. . . at the heart of science is an essential balance between two seemingly contradictory attitudes -- an openness to new ideas, no matter how bizarre or counterintuitive, and the most ruthlessly sceptical scrutiny of all ideas, old and new. This is how deep thoughts are winnowed from deep nonsense. Carl Sagan