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The KPNO 1.3-m Telescope---A Retrospective  (1Jun95)
(from KPNO, NOAO Newsletter No. 42, June 1995)

Budget constraints and the need to reduce operating costs have resulted in the
closing of the 1.3-m telescope as an observatory facility, with the last such
scheduled night on 11 April 1995. This telescope had been in service on Kitt
Peak for nearly 30 years, and a brief review of its history seems appropriate.

The telescope was originally proposed by the Space Sciences Division at
KPNO as the Remote Control Telescope System (RTCS) to be an engineering
research platform for the development of remote control protocols for
envisioned orbital telescopes. The telescope, to be located on Kitt Peak, would
be operated from Tucson, using commercial telephone lines for control and
data transmission. By the end of 1963, the telescope mount was installed at the
downtown office for testing of the communications system and control
console. The telescope was moved to its present location in 1965 and the
50-inch metal mirror was installed by the end of that year. By that time, the
goal was a fully automated remote-control telescope for ground-based
astronomy. This was a conceptual precursor of today's robotic telescopes,
somewhat disadvantaged by the computer hardware available at that time. The
control electronics occupied five large racks which almost filled the
present-day telescope assistant electronics lab.

By 1969, the telescope was transferred to the Stellar Division, to be operated
in manual mode, in part to reduce operating costs. The present observing floor
was installed, and the 50-inch became a full-time visitor facility in April of
that year. Shortly thereafter, the metal optics were replaced by the present
Cer-Vit optics, and the telescope entered the role of optical and infrared
photometry, which continued for 25 years. Refinements such as the chopping
secondary, observing room (built in part to escape the noise made by the first
chopping secondary), TV guiding, and computerization made the operation
more comfortable and efficient.

This telescope has played a pivotal role in the development of infrared arrays
for astronomical applications, as well as the IR instrumentation (IRIM, CRSP,
SQIID, COB) used on the Kitt Peak telescopes. By using the 1.3-m telescope
as a test and engineering facility for new, complex instrumentation, the need
for significant engineering time when using these instruments on the 2.1-m and
4-m telescopes was virtually eliminated. Finally, the observing record of IRIM
(eight years) and SQIID (four years) points out the scientific value of a modest
aperture, wide field telescope for infrared surveys and imaging of spatially
extended regions. We expect that the forthcoming 1024 X� 1024 ALADDIN InSb
arrays will help retain this valuable capability.

Dick Joyce

                               [Photo not included]

        The 50-inch RCT after its 1965 installation on Kitt Peak. During its
        service with the metal primary mirror, the telescope was stowed
        pointing at the nadir, with heat lamps to prevent condensation on the
        optics.

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