Combination of The Astrographic Catalogue With Hipparcos
The vast amount of work invested in the Astrographic Catalogue, taking plates, measuring, and publishing, looked for a long time as giving only a marginal scientific profit. But today, astronomers are very much indebted to this great effort because of the possibility of combining these century-old star positions with the results from ESA's Hipparcos space astrometry satellite, allowing high accuracy proper motions to be derived for 2.5 million stars. Specifically, the Astrographic Catalogue positions were transferred from the decades-old printed catalogues into machine readable form (undertaken at the Sternberg Astronomical Institute in Moscow under the leadership of A. Kuzmin) between 1987–94. The data were then reduced anew (at the US Naval Observatory in Washington under the leadership of Sean Urban), using the reference stars measured by the Hipparcos astrometry satellite. The 120,000 highest accuracy stars from the Hipparcos Catalogue were used to establish a detailed reference framework at the various epochs of the Astrographic Catalogue plates, while the 2.5 million stars in the Tycho-2 Catalogue provided a dense reference framework to allow the plate distortions to be accurately calibrated and corrected. The proper motions of all the Tycho Catalogue stars could then be derived especially thanks to the Astrographic Catalogue, but additionally using star positions from more than 140 other ground-based catalogues. Aside from the 120,000 stars of the Hipparcos Catalogue itself, the resulting Tycho-2 Catalogue (compiled at the Copenhagen University Observatory under the leadership of Erik Høg) is now the largest, most accurate and most complete, star catalogue of the brightest stars on the sky. It is currently the basis for deriving positions for all fainter stars on the sky. Sean Urban of the US Naval Observatory wrote in 1998:
The history of the Astrographic Catalogue endeavour is one of dedicated individuals devoting tedious decades of their careers to a single goal. Some believe it is also the story of how the best European observatories of the 19th century lost their leadership in astronomical research by committing so many resources to this one undertaking. Long portrayed as an object lesson in overambition, the Astrographic Catalogue has more recently turned into a lesson in the way that old data can find new uses.
Read more about this topic: Carte Du Ciel
Famous quotes containing the words combination of the, combination of, combination and/or catalogue:
“By the “mud-sill” theory it is assumed that labor and education are incompatible; and any practical combination of them impossible. According to that theory, a blind horse upon a tread-mill, is a perfect illustration of what a laborer should be—all the better for being blind, that he could not tread out of place, or kick understandingly.... Free labor insists on universal education.”
—Abraham Lincoln (1809–1865)
“[The pleasures of writing] correspond exactly to the pleasures of reading, the bliss, the felicity of a phrase is shared by writer and reader: by the satisfied writer and the grateful reader, or—which is the same thing—by the artist grateful to the unknown force in his mind that has suggested a combination of images and by the artistic reader whom his combination satisfies.”
—Vladimir Nabokov (1899–1977)
“Hats have never at all been one of the vexing problems of my life, but, indifferent as I am, these render me speechless. I should think a well-taught and tasteful American milliner would go mad in England, and eventually hang herself with bolts of green and scarlet ribbon—the favorite colour combination in Liverpool.”
—Willa Cather (1876–1947)
“Ay, in the catalogue ye go for men,
As hounds and greyhounds, mongrels, spaniels, curs,
Shoughs, water-rugs, and demi-wolves, are clept
All by the name of dogs.”
—William Shakespeare (1564–1616)