Young's Photo Gallery
James W. Young,
Photographic History of Table Mountain
Part 6: Larger Optical Telescopes,
Optical Programs Expand
By James W. Young
retired astronomer from Table Mountain Observatory
The Cloudcroft, New Mexico 48-inch f6.5 Newtonian/Cassegrain used
Telescope was acquired and brought to Table Mountain Observatory,
and housed in Building number TM-27.
Another new telescope building was constructed to house a 1.2
telescope once used by the U.S. Military to image Earth orbiting
satellites during the cold
war. JPL's only initial expence was $72,000 in shipping
charges. This newly constructed
building to house the telescope, telescope control room, electronics
shop, and utility room
for the vacuum chamber room (to coat the entire observatory's telescope
mirrors) was an
additional $250,000. Construction was started in the Summer of
Foundation for the 48-inch
telescope building - June 1988
The foundation, including the
center telescope pier - July 1988
Watching the new building
take shape; (R to L) Ed Tyson, the original engineer in charge of
the 48-inch telescope when it was used in Cloudcroft in the 1960s,
Kevin Hernandez, a new
JPL employee to oversee the eventual 48-inch telescope operations, and
the observatory site facility secretary. Tyson, with his wife
Roberta (far left), came to
Table Mountain to supervise the specific concrete pier foundation and
The telescope base mounting plate
- August 1988
The round dome-shaped building
part continues to grow with the outside walls taking shape
(the last two images taken from the site's 90-foot telphone pole) -
The top of the dome wall section
being prepared for the new 30-foot Ash Dome ledge ring.
The other portion of the
building starting to take shape - September 1988
Control room, electronics
shop, and utility room almost finished - September 1988
The 30-foot Ash Dome was
constructed on the ground next to the building...
A crane lifted the finished dome,
and placed it on the round dome building section.
The finishing touches of the entire
building exterior in early October 1988
One last look from the 90-foot
pole - October 1988
Last minute exterior
The outside of TM-27 is
A view of TM-27 taken several
years later showing the AC units (lower right center), to be
described later - Summer 1998
The two central piers to hold the 'track' axis for the alt-alt-azimuth
Tyson preparing to hoist the track and cross-track center hub onto the
The twin piers and center hub ready for the long telescope tube assembly
The center section of the telecope tube has a new off-axis Cassegrain
f/29 focus hole and
bracket assembly prepared by our facility's machinist, Bruce Williamson.
The entire telescope tube, with its new Cassegrain round mounting plate
attached, is swung
into the dome and attached to the track and cross-track axis mounting
The completed tube assembly and pier section painted, ready for
operation in 1989
A second view of the telescope assembly
A visitor from Australia, Ken Stevens, gives a good size comparison of
this large telescope
in late 1989.
The 48-inch telescope's dedication in 1989 had (L to R) Mustafa
Chahine, Dan Sidwell, and
Jack Tallon in attendance.
During the telescope dedication, visitors included Marjorie and Aden
Meinel (the former
director of the Kitt Peak National Observatory in Arizona) standing
with Dan Sidwell (Table
Mountain's site manager) 1989.
By 1990, Kevin Hernandez was moved to another JPL position, and Karl
Klett assumed the
new position for the 48-inch telescope operations.
After considerable discussions on the seeing characteristics at Table
Mountain, a study of
the seeing conditions revealed the need to 'air condition' the dome
interior during the day
in preparation for the night-time temperatures. Both TM-12 and
TM-27 domes were then
insulated using three-inch thick irregular shaped panels and bolted to
the interior dome skin
curved walls...a very tedious task in 1992. Two large air
conditioning units were installed
inside this dome, whereas only one unit was needed in the 24-inch
Attaching the insulation panels at the top of the 48-inch telescope
interior dome skin...
Karl Klett at the control room console in 1993. The Control
software for the telescope was
still in the making by a new sub-contractor from Colorado, Gary
Time to try out the vacuum chamber, under the direction of Tyson
(left), with onlookers,
Don Young (right), and Klett. The author was being trained to do
this process under the
watchful eyes of Tyson (this, his second trip to the observatory to
assist for the new
The vacuum chamber, with its roughing pump in the foreground, its
cryo-pump to the right
with the blue label, and the associated electronics to the left.
The chamber's gases were
pumped out and up the black ABS vertical pipe through a ceiling vent
and hood on the roof.
A new hoist to lift the mirror using the mirror's collar to swing it in
place onto the vacuum
chamber's internal bracket support. See the next image. The
mirror was cleaned of its
prior silver coating using chemicals, room ventilation, and PPEs for
safety purposes. The
seemingly visual mirror imperfections seen here, are actually bubbles
and holes inside and
on the back of the un-silvered mirror.
The final cleaning and preparation of the mirror for coating in the
chamber by the author.
The finished product, the first test, was done in May 1993.
Aluminum was used, as silver
coating was extremely toxic. TM-27 was never set up to do silver
coating, so aluminum was
the easiest choice. Here, Klett is admiring our first results.
The second coating operation was done a week later, and the final
results were superior to
the first one. Here the author shows his satisfaction to the
Under very careful scrutiny, the mirror could be washed of dirt and
grime while still in the
mirror cell and telescope. The excess distilled water was
vacuumed off the surface, and a
small amount of ethyl alcohol was used to help remove the excess water
drops. With three
people, the entire operation of removing the mirror, cleaning it,
coating in the chamber, and
returning to the telescope was four total days.
After Karl Klett resigned so he could return to assist his ailing
parents in Pennsylvania, JPL
hired Steve Gillam to take over the 48-inch operations. A good move,
since Gillam had been
a student of Gary Grasdalen in Wyoming many years earlier.
Here, Grasdalen is seen here working on the software to control the
48-inch telescope. He
wrote a completely new telescope control program, using Borland C++.
Grasdalen made several 'clients' to operate the various telescope and
dome functions into a
MS Windows platform for a single computer. Despite many years of
program was never able to completely control the telescope, especially
under windy weather
conditions. The telescope would occasionally 'get away', and
crash into the dome wall edge.
Although some science was done with this instrument by Padma
Yanamandra-Fisher in 1994.
the telescope was never really used for any in-depth astronomy
science. It was eventually
removed after being sold to an outside group.
The author visited the Lowell Observatory to see an old 1-meter
telescope they had for
possible sale to replace the 48-inch at Table Mountain. This
instrument, seen here in
storage, was purchased after the author retired from JPL.
Here is the restored 1-meter Lowell telescope now in the 30-foot dome
that used to house
the Cloudcroft 48-inch telescope. It has been in operation to
this day (2020).
End of Part 6B
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