Showing posts with label Bayer. Show all posts
Showing posts with label Bayer. Show all posts

Tuesday, August 24, 2010

Where did all Bayer's letters go?

Johann Bayer published his celebrated Uranometria atlas in 1603, and it's from there that we get many of the Greek designations, such as Alpha Centauri. But did you know that, when he'd exhausted all 24 letters of the Greek alphabet, he assigned stars Roman letters?

He started with A (because a could easily be confused with α), and the proceeded from b, down the lower-case alphabet, only ocasionally getting into the 2nd half of the alphabet. It's where we get names such as h Persei, p Eridani and so on.

But have you noticed that they've been disappearing over the past thirty years?

In 1979, Dorrit Hoffleit (astronomer at Yale University) in her paper, "Discordances in Star Designations", pleaded that all roman letters, other than that for Variable stars, be excluded from future catalogues. When she released the 5th edition of the Bright Star Catalogue, that's exactly what she did. The letters were gone. In the popular Sky Catalogue 2000.0 (1982), all but a few Bayer letters were expunged.

But not everyone wants to lose these designations and be forced to use cumbersome catalogue numbers for these stars. Atlases continue to use them, and Morgan Wagman, in his book Lost Stars, goes as far as saying that this practice is patently unfair and discriminatory against stars with Roman letters.

I have sympathies both ways. Without roman letters, many stars remain unlettered, and we're forced to use long catalogue numbers. This is particularly so in the Southern Hemisphere (until we make better use of Gould Numbers). We need further simple designations to use. But I also understand the other side of the argument. Many of the lower-case Roman letters are frequently confused with the Greek ones, meaning that most atlases and catalogues over the past fifty years have multiple errors.

What's the solution? Should we restore them or not? Or should we make some sort of compromise?

Wednesday, August 4, 2010

A History of Modern Star Designations

(condensed, with tongue slightly in cheek)

In the 1603, Bayer assigned Greek letters to stars in each constellation, but some were so badly drawn, you couldn’t tell what star he meant. Flamsteed tried to fix things up, but he was missing the catalogue that went with the atlas, and he only made things worse.

Then Lacaille mapped the southern constellations and used so many letters, people couldn’t discriminate the ο with the o, the χ with the x, and atlases still get them confused (I kid you not!). Bode added some designations, but people forgot most of them. Baily spent considerable effort tracking down Flamsteed's errors, but not everyone listened to him. Argelander reckoned if he couldn’t see a star, it didn’t deserve a designation--so he removed it, no matter what Baily said. Heis had better eyesight, but he sided with his buddy anyway. Gould then removed some more designations, and re-added others had deleted...

Finally, in 1930, the IAU stepped in and defined the Constellation boundaries once and for all. But they didn't think to standardize the nomenclature of stars at the same time, so we're left with a mess where stars designated Norma are in Scorpio, stars designated as being in Orion are in Monoceros. Astronomers and cartographers follow whatever convention they see fit to. And they call astronomy a science! ☺