University of Wyoming 2.3-meter Telescope (WIRO)
The University of Wyomings 2.3-meter telescope is located at the Wyoming
Infrared Observatory (WIRO) about 25 miles southwest of Laramie, WY on the
summit of Jelm Mt. and at an altitude of 9656 ft. (2943m). This site
was chosen because: (1) the dryness of the air, an important consideration
for infrared astronomy since moisture strongly absorbs infrared radiation,
(2) comparatively low turbulence in the air above the mountain, (3) a dark
night sky, (4) close proximity to the University of Wyoming, and (5) pre-existing
road, electricity and phone lines since Jelm was formerly used by the US Forest
Service and BLM as a fire lookout station.
The planning for WIRO began in the early 1970s. Funding for the facility
was obtained in 1975 from the Wyoming State Legislature (contributing 60%)
and from the National Science Foundation (40%). The total construction
costs were nearly two million dollars. WIRO became operational in September
of 1977 and it still ranks as one of the premier infrared observatories in
the world.
The weather on Jelm can be extreme Winter temperatures can drop below
-40 F and wind speeds can occationally exceed 100 mph. Snow covers
the road from October until May and can limit travel on the mountain to Sno-Cats
and ATVs. In the spring and summer, lightning is a serious threat to
the sensitive electronics at the observatory requiring extensive efforts to
isolate and protect this equipment.
Optical Design
The design of the WIRO 2.3 meter telescope is a classical Cassegrain (see
right-hand figure below). This includes a large, concave primary mirror
with a paraboloic surface and a smaller, concave seconday mirror with a hyperbolic
shape. This allows for two optical configurations. At the prime
focus the light from a distant object is brought to a focus about 5 meters
above the primary mirror's surface. This is the location for the main
imaging cameras for WIRO as it provides the largest field of view.
In the Cassegrain configuration an 8" diameter convex secondary mirror is
placed in the converging beam to intercept the light before it reaches the
prime focus and send it back down the length of the telescope and through
a hole in the primary mirror to form a secondary image about 1 meter behind
the primary mirror (see left-hand figure below). This configuration
provides a smaller field of view but a better imaging scale for smaller astronomical
objects. In addition, the location of this secondary image allows for
much larger instruments to be placed behind the primary mirror on the rear
surface of the telescope structure. The secondary mirror can be "chopped"
or wobbled under computer control to allow for rapid, alternating sampling
of an astronomical object and the nearby, blank sky. This enables the most
accurate measurements at mid-infrared wavelengths since at this wavelength
the "dark" night sky is actually quite bright and variable.
Telescope Structure and Dome Enclosure
The telescope needs to be precisely pointed and must track across the sky
to follow the apparant motion of an object from East to West as the Earth
rotates. The telescope mount was manufactured by L&F Industries
of Huntington Park, CA at an origninal cost of nearly $700,000. The
combined weight of the telescope and its mount is about 110,000 lbs.
Of this, 60,000 lbs moves when the telescope is operated. However, the
precise balancing of the telescope means that the 30 tons of moving mass
can be moved with a 1/10 horsepower electric motor. The drive gears
are machined to very close tolerances and are capable of positioning the
telescope with an accuracy of 1/10 arcsecond (1/36,000 of a degree).
The telescope is operated under computer control in order to model and correct
for the flexture of the telescope structure as it is pointed toward different
positions on the sky.
The hemispherical dome, which shelters the telescope and its instrumentation,
is 45 feet in diameter. The dome was designed and constructed by Observa-Dome
Laboratories of Jackson, Mississippi. It features a 10-foot wide "slit"
which can be opened for observations and rests on 18 rollers such that it
can be driven by three 1 horsepower motors to follow the telescope as it
points to various objects and tracks them across the sky. The telscope
and instrument control room is located in an adjacent building to the telescope
dome. This building also contains a small laboratory for instrument
preparation and repair. The lab features a selection of tools and a
turbofan vacuum pump for dewer and instrument maintainence. A small
machine shop is also available for more serious repairs!
Living Facilities
Observers at the 2.3-meter telescope usually stay at WIRO while observing.
The living facilites includes six dorm rooms, a full-function kitchen, a
bathroom, and a living room. The living room includes comfy chairs,
and an entertainment center with a broad collection of VHS tapes. No
satellite dish or DVD player is currently available but they're on the list
of must haves!
Observing at WIRO
Observing time is allocated on a quarterly basis to the faculty and students
of the Department of Physics and Astronomy. Interested visitors from
outside the deparment are encouraged to apply for time on the WIRO 2.3 meter.
The schedule for the Fourth quarter of 2004
shows the research programs currently scheduled on the telescope.
Scientists interested in obtaining observing time in the next quarter should
submit a one-page proposal to the the WIRO director using the one-line request
form by the appropriate deadline. The scheduling periods and deadlines are:
Deadline
Period
December 1
January-March
March 1
April-June
June 1
July-September
September 1
October-December
Current Instruments
WIRO-Prime:
the prime-focus imaging camera for the WIRO 2.3 meter telescope.
Currently limited to optical wavelengths (400 - 1000 nm).
WIRO-Spec:
the integral-field, holographic spectrograph for the WIRO 2.3 meter
telescope. Currently limited to optical wavelengths (400 - 1000 nm).
Goddard Infrared Camera:
256x256 InSb camera (Gold IR Dewar).
Instruments Under Development
WWF-Cam:
the new wide-field, near-infrared imaging camera for the WIRO 2.3 meter telescope.
Designed for large, near-infrared surveys at wavelengths (0.9 - 2.4 um).
Observing Proposals
A latex form and style file are available for observing proposals: