Queue Scheduled Observing
The HET operates a queue scheduled observing program. Under this system, operation of the telescope,
and the acquisition of targets on the nightly observing list is the primary responsibility of the
Resident Astronomer, who has flexibility to optimize the observing plan. This mode of operations
is particularly well suited to the HET because it makes full use of the entire night for the maximum
scientific output. Optimized scheduling overcomes any drawback from the telescope accessing specific
areas of the sky only in specific windows of time. The observing program functions superbly for
large-scale spectroscopic surveys, rapid follow-up inspections of just discovered, and often short-lived
(explosive), astronomical events, and long-term monitoring by periodically re-observing the evolving
spectra of some kinds of objects.
Queue scheduled observing brings further significant benefits. It largely "immunizes" participating
investigators from bad weather, since the Resident Astronomer has extensive observing time flexibility
unlike the irreplaceable time slot awarded to the traditional visitor-observer. Secondly, the observing
service provided by a resident observer saves on overall expenses and resources, and avoids
equipment-use errors from lack of familiarity on the part of an infrequent visitor-observer.
Many systems of the HET are remarkable for their precision and creatively engineered design. The truss
supporting the primary mirror array fits this category. The truss was made by MERO Industries, in
Wuerzburg, Germany, at extremely low cost. The steel balls shown above were robotically milled into
truss nodes, like the example at left, part of MERO's patented connection technique.
The structure is made from 383 nodes and 1,747 struts. Few of the parts are interchangable. The struts
were manufactured to a precision of 0.0004 inches, about one-tenth the thickness of a human hair. Before
shipment to Texas, the truss was test assembled. Each node in the top surface of the truss was accurate
to its theoretical position to better than 0.08 inches.
At McDonald Observatory, the pieces arrived in a single truckload and were assembled in six weeks by a
MERO crew. Under the dome of the HET, and the 27,000 pound weight of the primary mirror, the truss is
deflected just 2.5 millimeters.
Images and Amazing Truss content courtesy of The West Texas Time
Machine: Creating the Hobby-Eberly Telescope, Little Hands of Concrete Productions, 1998.