Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1939-08-19
FATHER.
son, STARGAZERS
DENIS n. O'BRIEN SIR. AND JR.
have BIG TELESCOPE IN
THEIR BACK YARD
After Four Years OF Experimenting
They Nov Use Instrument with s.
Inch Lense which They Ground
Themselves.

Inch Lense which They Ground
Themselves.
Denis H. O'Brien, insurance
agent and director of the Billings
Municipal band, and his 1o-year-
old son, Denis IT,, a sophomore in
mechanical engineering at Montana
State college, are full-fledged
mem bers of T. N. telescope nuts),
term applied to the some 10000
"back yard astronomers" now ac-
tive in the United States.
After four years of experimenting
and work on different type telescopes.
the OBrienS now have scope with a
six-inch lens that is correct to mil
lionth of an inch with which they
scan the heavens from the back yard
of their home. 1t took them IS hours
Of actual work to grind the lens to
its present correctness. All work on the
telescope, from the lens to the five
foot tube, was done by the O,Briens,
elder and junior, because that Is half
the fun Of being T. NJ, they explain.
In addition to the IS hours of work
on the lens, there were many long
hours. but nevertheless interesting
hours. spent in testing the mirror. Pre-
cision instruments cannot measure the
lens, Senior O'Brien says, but 1t must
be tested continually with light rays. |
It's a complicated process to the lay |
man, but an appealing one to the !
OBriens and the several other anna
teur astronomers in Billings.
Work Telescope Overtime
This summer the OBrien telescope |
has been working overtime, because Of |
tl,a r., he a. v1Iu ar
Mars. Each night automatically mind |
ed friends collect in the back yard and /
have turns peering through the in |
strument at the planet some $4,000, 900 !
miles away, the closest it has been to
the earth In the last is years.
The telescope has been attached to
a temporary mount, but soon it will
struction by the father and son, that
will move the scope to compensate with
the earth's rotation and thus keep
right on a star that would otherwise
flash out Of the telescopes field. While
looking at Mars, the instrument has
to be moved slowly. or the planet viii
be lost from view as the earth ro-
tates away from it.
In addition to the large Six-inch
telescope the O'Brien Observatory"
boasts an r. F. T. telescope, so called
because 1t views the sky on a wider
angle and brings In a much larger
field of stars than the big tube. But
the six-inch apparatus is the practical
one, and of the same size that has
been used in making most major dis
eoveries in astronomy. 1t is with this
telescope that the T. Ms spend most
If their time these clear nights. !
The Altitude Helps
Montana is an excellent location for '
according to O'Brien ST.,
because of the altitude, rarified air
md little smoke or fog: He knows Of
,mer, who was bitten by the bug and
ipent some time and many dollars ]
constructing a first-rate telescope. The !
asst O'Brien heard about him he had /
,een waiting four years to get a clear {
light so he could put his instrument
nto operation. The winter, because of
is clear nights, is the ideal time for
targazing, but this summer has been
'Ood, with but a few nights being
poiled by smoke from forest fires.
The telescope cuts through some
moke. but the haze makes the planets
nd stars indistinct. The O'Briens can
airy their scope from 81 to 240 power,
ody that much. Mars, which with the
aked eye looks like a lantern hang
1g in the southeastern sky, Is brought
ut to look like a moon, or some
lockers" say an orange, with a dark
pot visible In the center. At times the
,e cap, which tops the planet, Is
hougat visible through the instru-
lent.
GROUNDWORK" Required
Astronomy is interesting work for
lenis and Denis. But before they ever
tarted grinding a lens they spent
ours studying the subject. 1t takes a
reat deal Of groundwork even to be
T. NJ, they say Now several high
shool students have taken up the
Obby and soon some plan will prob
bly, be made to form an amateur
club. There are many
over the United States.
But it's not all stars and planets
nee not long ago, the elder OBrien
as catching up on his homework one
light, looking at the moon, when he
wv a large bird fly across its surface,
hen another until a whole flock were
inging through the field on his tele- 4
;ope. After a flustered minute, he
saiized that he hadn't discovered any
noon birds" but rather that he was
ewing q flock of geese flying north
svera1 thousand feet high. 4