38 AUSTRALIAN SKY & TELESCOPE APRIL 2016
Lowell Observatory has a long tradition of
designing and fabricating instruments and telescope
modifications,andithasalwaysretainedacadreof
specialistsandfacilitiestothatend.Thissavedmoney
andprovidedthein-houseexpertisetodothebest
possible restoration job without cutting corners. For
example,coauthorRalphNye,DirectorofTechnical
Services,hasworkedatLowellsince19 7 6.He’sin
charge of mechanical engineering and maintains
the Clark and eight other telescopes, including
instrumentation for the observatory’s new 4 .3-metre
Discovery Channel Telescope.
No documentation exists for how the telescope
wasoriginallyputinplace.SoNye’srestoration
plan centred on taking the instrument apart safely
(photographing all parts and their locations),
designingandfabricatingcustomarrangementsto
process some seven tonnes of parts, and restoring the
wooden dome without damaging it.
Theundertakinginvolvedseveralkeysteps.First,
we locked down the telescope’s9.7-metre-long tube
paralleltothegroundusingtwospecialfixturesthat
bolted to existing holes on the cast iron centre section
of the tube, then attached these to the mount pedestal
using specially designed turnbuckles reminiscent of a
truckdriveshaft.Asimilarbracewasusedtosupport
the five 19 0-kg right-ascension counterweights.
Wecarefullyremovedseveraltreesnearthe
dome to allow room for a50-metre crane to remove
large components through the dome’s shutters. To
facilitate this, we stripped the telescope of all small
parts, along with its 1 0- and30-cm Alvan Clark and
Sons finder telescopes.
The priceless 6 1-cm Clark lens assembly was next
inlineforremoval,butthisposedaproblem.SinceDON’T
SCRATCH
Left:The 6 1-cm
objective lens
after removal of
the lens cap and
the adjustable-
aperture iris
diaphragm that
early observers
sometimes used.
Despite a coating
of dust and
pollen, the lens
was otherwise
in good shape.
Right:Ralph
Nye(left)and
Peter Rosenthal
carefully clean the
rear, flint-glass
elementofthe
disassembled
61-cm objective. LOWELL OBSERVATORY(2)the telescope was now locked in place horizontally,
the dome could not be rotated freely to allow access to
the lens through the dome shutter. We cut a hole in
the dome ceiling and lowered a 12-metre strap to lift
off the 1 0 5-kg lens cell! Before that, however, we had
to remove two of the counterweights to balance out
the expected weight loss due to removal of the lens
assembly and, later, the upper and lower tube sections.
Prior to removing the 3 9 0-kg front tube section, we
braced a massive wooden beam between the floor and
the back section of the tube for added safety and to
minimise stress on the temporary support rods.
Since the mount’s polar axis is aimed 35° above
horizontal (Flagstaff’s latitude), and the 435-kg polar
shaft would be extremely difficult to remove at such an
angle, Nye designed an I-beam support structure set at
–35°, to tilt the whole mounting at an unnatural angle.
This allowed removal and reinstallation of the polar
shaft with a horizontal pull or push.
The telescope had last been serviced several
decades before, and at that time many of its parts were
treated with lead-based paint to minimise corrosion.
To address the lead-paint toxicity problem, we built
a wooden fixture allowing the two telescope tube
sections to be rolled and treated with a lead-paint
stripper and neutraliser. We refinished the tube and
many other large parts with a silver-grey powder
coating. All other parts and accessories were cleaned
and restored to the point where we could do nothing
more to make them work or look any better.
By far the most delicate and precious components
of this classic telescope were the irreplaceable 30-cm
and 61-cm Clark objective lenses. The fronts of both
objectives were covered with years of dust, pine pollen
and contaminants, but were otherwise unharmed.Restoring a classic