Daily independent. [volume] (Elko, Nev.) 188?-1915, 1891-04-29
PHOTOGRAPHERS STARS.

York the other evening upon astronom-
ical photography. He said, observes
Pittsburgh Dispatch writer, that as
Economical photography presented few
difficulties, and that more knowledge
of astronomy was required than of
photography by the observer; in other
words, that the ratio between the two
was about three parts of astronomy to
one part Of photography.
If, however, n photographer should
attempt to photograph star he would
find that his image would be blurred,
owing to the movement of the object
during the exposure; therefore it was
necessary that the instrument must be
kept in motion in keeping with the mo-
ton Of the star, and the apparatus for
photographing stars, therefore, adjusted
to meet these difficulties. The usual
method of keeping the star on the plate
in photographing was by moving the
telescope, but owing to the size of the
instrument ut the Lick Observatory this
was impossible, as the telescope weighed
seven tons. The plan adopted, there
fore, was to make the plate movable by
means of turning screws.
When the photographer wished to do
done was to move the big telescope so
that lens could be capped over the
end. 1t is necessary to put on
different lens for Photographic
purposes, and it happens that
n different focus is obtained in
the big telescope. The dry plate
is therefore placed in the tube nine
feet from the eye piece, a hole having
been cut in it for that purpose. A. seed
twenty-siX-plate is used, and for develop
ment an ordinary pyro and potash. The
developer is used very weak and plenty
of time given to bring out the image.
When the plate is developed the opera
tor has to go at it in blind sort of fash
ion, as the smaller star images will
not appear till the developing work is
done.
The photographs of the planets are
more difficult to secure, owing to the
refraction in the atmosphere. Some
fairly good pictures have, however, been
made of Jupiter and Saturn, and pic
lures of Mars will be taken. Prof.
Keller showed pictures of the planets
and the moon, us we'll as drawings to
illustrate the difference between the
two. The outer ring of Saturn, which
was not discovered till the big Lick tel
escope was turned on the planet, does
not show in the photograph. The pic
lures of the Milky Way which Prof.
Neeler has in his collection of lantern
slides are most excellent, and are the
best ever taken. The hundreds of stars
shown on the picture are none of them
visible to the naked eve.
The photographs of the planet Jupiter
showed plainly the different positions of
the spots and bands on the surface of
the planet, which demonstrate that they
are constantly changing, and that prob
ably the surface of Jupiter is a mass of
changing matter.
1t is IL well-llnown fact that better
photos are obtained through the smaller
telescopes than through the big ones.
Photographing the stars, especially the
small ones, is tedious work, as III some
cases the exposure must last for several
hours. Diving al that time the plate
nr tclcscug aust be moved so that the
image o. TIA. star will continue in one
place. The exposure for star of the
sixteenth magnitude is two hours, and
only one at a time can be secured I'M
less the stars happen to be of the same
magnitude, SO that getting clusters is
particularly long and tedious in IL pc
Yution.
In procuring the Photographic star
pictures, Otter what is known as the
trailing process !. 'ilowed-that is, the
plate is exposed t. - star, and then no
attempt is mndc to fix the image in one
place, but IL .'.55es along over the plate,
making IL tran. 4 number of trails Gun,
OF course, be go6 On one plate, and then
studied ont and measured aftcrward
The exposures for planets arc short
thnt OF sun spot taken in Paris was
shout as lightning-lil1e as possible, the
shutter being attached to the strongest
kind Of a Spring. The exposure for the
MOON takes about quarter of IL second,
and that for Jupiter about four seconds.
People who visit the Lick Observatory
often ask very remarkable questions in
regard TO tho telescope us well rs to the