86
5 Nearly Half a Million Stars
similar telescopes from the Anglo-Australian Observatory in Australia, and the
European Southern Observatory (ESO) in Chile. The results of these surveys
are now publicly available electronically as the Digital Sky Survey [52] More
recently this has been replaced by the Sloan Digital Sky Survey [53], which goes
deeper but covers only a limited part of the sky.
Kapteyn actively participated in the Carte du Ciel, partly because he was
(after some time) elected to the Permanent Committee. He tried to convince
the leadership of the project to adopt his parallactic method for measuring
the plates. The project actually did allocate funds to him to build a prototype to be used in the production of the Carte du Ciel, but eventually the
method was rejected. The procedure of rectangular coordinates chosen by the
Committee was indeed potentially more accurate, but if—as happened—the
measurements are not reduced to celestial coordinates, it is not a very useful
approach. Kapteyn also suggested carrying out the observational procedure in
such a way that parallaxes and proper motions could be determined on a large
scale. He proposed to do the exposures of each field three times on the same
photographic plate, but contrary to the adopted procedure with six months
intervals. In principle, you can then measure the parallax and proper motion
from the displacement of the stars between those three times. But then you
twice have to leave the plate half a year undeveloped and only develop it when
the third exposure was done. This proposal of Kapteyn was not accepted either.
Eventually Kapteyn stopped his activities for the Carte du Ciel. Figure 5.11
shows Kapteyn during the times when all this was happening.
The Carte du Ciel also became a threat to the CPD; this was mainly the result
of some animosity between David Gill and William Mahoney Christie (1845–
1922), Astronomer Royal and director of the Royal Greenwich Observatory
(see Fig. 5.10). Christie was jealous of Gill and convinced the Royal Society to
stop subsidies to Gill for the CPD in 1887. Among other things, he claimed
that far fewer stars appeared on the plates than was expected. That was pure
nonsense, as the final total number of almost half a million illustrates. When
other countries offered to support Gill financially, Christie threatened to stop
the English participation in the Carte du Ciel if these funds were accepted
by Gill. In the end, Gill paid for the project out of his own pocket; his wife
gave up her carriage and Gill even stopped smoking cigars! ‘We will somehow
manage it together even if I have to give up tobacco,—which God forbids’,
Gill wrote to Kapteyn. In the end, Christie’s misconduct was exposed and he
was deprived of his previous authority to advise on the Cape Observatory. Gill
suffered financially, but Christie suffered in terms of reputation. By way of
illustration: two important prizes in astronomy were (and are) the Gold Medal
of the Royal Astronomical Society and the Catherine Wolfe Bruce Gold Medal
5 Nearly Half a Million Stars
similar telescopes from the Anglo-Australian Observatory in Australia, and the
European Southern Observatory (ESO) in Chile. The results of these surveys
are now publicly available electronically as the Digital Sky Survey [52] More
recently this has been replaced by the Sloan Digital Sky Survey [53], which goes
deeper but covers only a limited part of the sky.
Kapteyn actively participated in the Carte du Ciel, partly because he was
(after some time) elected to the Permanent Committee. He tried to convince
the leadership of the project to adopt his parallactic method for measuring
the plates. The project actually did allocate funds to him to build a prototype to be used in the production of the Carte du Ciel, but eventually the
method was rejected. The procedure of rectangular coordinates chosen by the
Committee was indeed potentially more accurate, but if—as happened—the
measurements are not reduced to celestial coordinates, it is not a very useful
approach. Kapteyn also suggested carrying out the observational procedure in
such a way that parallaxes and proper motions could be determined on a large
scale. He proposed to do the exposures of each field three times on the same
photographic plate, but contrary to the adopted procedure with six months
intervals. In principle, you can then measure the parallax and proper motion
from the displacement of the stars between those three times. But then you
twice have to leave the plate half a year undeveloped and only develop it when
the third exposure was done. This proposal of Kapteyn was not accepted either.
Eventually Kapteyn stopped his activities for the Carte du Ciel. Figure 5.11
shows Kapteyn during the times when all this was happening.
The Carte du Ciel also became a threat to the CPD; this was mainly the result
of some animosity between David Gill and William Mahoney Christie (1845–
1922), Astronomer Royal and director of the Royal Greenwich Observatory
(see Fig. 5.10). Christie was jealous of Gill and convinced the Royal Society to
stop subsidies to Gill for the CPD in 1887. Among other things, he claimed
that far fewer stars appeared on the plates than was expected. That was pure
nonsense, as the final total number of almost half a million illustrates. When
other countries offered to support Gill financially, Christie threatened to stop
the English participation in the Carte du Ciel if these funds were accepted
by Gill. In the end, Gill paid for the project out of his own pocket; his wife
gave up her carriage and Gill even stopped smoking cigars! ‘We will somehow
manage it together even if I have to give up tobacco,—which God forbids’,
Gill wrote to Kapteyn. In the end, Christie’s misconduct was exposed and he
was deprived of his previous authority to advise on the Cape Observatory. Gill
suffered financially, but Christie suffered in terms of reputation. By way of
illustration: two important prizes in astronomy were (and are) the Gold Medal
of the Royal Astronomical Society and the Catherine Wolfe Bruce Gold Medal