Robotic
telescope
A robotic telescope is an astronomical telescope
and detector system that makes observations without the
intervention of a human. In astronomical disciplines, a telescope
qualifies as robotic if it makes those observations without being
operated by a human, even if a human has to initiate the
observations at the beginning of the night, or end them in the
morning. A robotic telescope is distinct from a remote telescope,
though an instrument can be both robotic and remote.
Design
Robotic telescopes are complex systems that typically incorporate a
number of subsystems. These subsystems include devices that provide
telescope pointing capability, operation of the detector (typically
a CCD camera), control of the dome or telescope enclosure, control
over the telescope's focuser, detection of weather conditions, and
other capabilities. Frequently these varying subsystems are
presided over by a master control system, which is almost always a
software component.
Robotic telescopes operate under closed loop or open loop
principles. In an open loop system, a robotic telescope system
points itself and collects its data without inspecting the results
of its operations to insure it is operating properly. An open loop
telescope is sometimes said to be operating on faith, in that if
something goes wrong, there is no way for the control system to
detect it and compensate.
A closed loop system has the capability to evaluate its operations
through redundant inputs to detect errors. A common such input
would be position encoders on the telescope's axes of motion, or
the capability of evaluating the system's images to insure it was
pointed at the correct field of view when they were exposed.
Most robotic telescopes are small telescopes. While large
observatory instruments may be highly automated, few are operated
without attendants.
History of professional robotic telescopes
Robotic telescopes were first developed by astronomers after
electromechanical interfaces to computers became common at
observatories. Early examples were expensive, had limited
capabilities, and included a large number of unique subsystems,
both in hardware and software. This contributed to a lack of
progress in the development of robotic telescopes early in their
history.
By the early 1980s, with the availability of cheap computers,
several viable robotic telescope projects were conceived, and a few
were developed. The 1985 book, Microcomputer Control of Telescopes,
by Russel M. Genet and Mark Trueblood, was a landmark engineering
study in the field. One of this book's achievements was pointing
out many reasons, some quite subtle, why telescopes could not be
reliably pointed using only basic astronomical calculations. The
concepts explored in this book later became fully articulated in
the telescope mount error modeling software called Tpoint.
Since the late 1980s, the University of Iowa has been in the
forefront of robotic telescope development on the professional
side. The Automated Telescope Facility (ATF), developed in the
early 1990s, was located on the roof of the physics building at the
University of Iowa in Iowa City. They went on to complete the Iowa
Robotic Observatory, a robotic and remote telescope at the private
Winer Observatory in 1997. This system successfully observed
variable stars and contributed observations to dozens of scientific
papers. In May 2002, they completed the Rigel Telescope. Each of
these was a progression toward a more automated and utilitarian
observatory.
The Lincoln Near-Earth Asteroid Research (LINEAR) Project is
another example of a professional robotic telescope. LINEAR's
competitors, the Lowell Observatory Near-Earth-Object Search,
Catalina Sky Survey, Spacewatch, and others, have also developed
varying levels of automation.
In 2004, professional robotic telescopes were characterized by a
lack of design creativity and a reliance on closed source and
proprietary software. The software is usually unique to the
telescope it was designed for and cannot be used on any other
system. Often, robotic telescope software becomes impossible to
maintain and ultimately obsolete because the graduate students who
wrote it move on to new positions, and their institutions lose
their knowledge. On the other hand, professional systems generally
feature very high observing efficiency and reliability. There is
also an increasing tendency to adopt ASCOM technology at
professional facilities.
History of amateur robotic telescopes
In 2004, most robotic telescopes are in the hands of amateur
astronomers. A prerequisite for the explosion of amateur robotic
telescopes was the availability of relatively inexpensive CCD
cameras, which appeared on the commercial market in the early
1990s. These cameras not only allowed amateur astronomers to make
pleasing images of the night sky, but also encouraged more
sophisticated amateurs to pursue research projects in cooperation
with professional astronomers. The main motive behind the
development of amateur robotic telescopes has been the tedium of
making research-oriented astronomical observations, such as taking
endlessly repetitive images of a variable star.
In 1998, Bob Denny conceived of a software interface standard for
astronomical equipment, based on Microsoft's Component Object
Model, which he called the Astronomy Common Object Model (ASCOM).
He also wrote and published the first examples of this standard, in
the form of commercial telescope control and image analysis
programs, and several freeware components. He also convinced Doug
George to incorporate ASCOM capability into a commercial camera
control software program. Through this technology, a master control
system that integrated these applications could easily be written
in perl, VBScript, or JavaScript. A sample script of that nature
was provided by Denny.
Following coverage of ASCOM in Sky & Telescope magazine several
months later, ASCOM architects such as Bob Denny, Doug George, Tim
Long, and others later influenced ASCOM into becoming a set of
codified interface standards for freeware device drivers for
telescopes, CCD cameras, telescope focusers, and astronomical
observatory domes. As a result amateur robotic telescopes have
become increasingly more sophisticated and reliable, while software
costs have plunged. ASCOM has also been adopted for some
professional robotic telescopes.
Meanwhile, ASCOM users designed ever more capable master control
systems. Papers presented at the Minor Planet Amateur-Professional
Workshops (MPAPW) in 1999, 2000, and 2001 and the International
Amateur-Professional Photoelectric Photometry Conferences of 1998,
1999, 2000, 2001, 2002, and 2003 documented increasingly
sophisticated master control systems. Some of the capabilities of
these systems included automatic selection of observing targets,
the ability to interrupt observing or rearrange observing schedules
for targets of opportunity, automatic selection of guide stars, and
sophisticated error detection and correction algorithms. None of
these were features of any documented robotic telescope,
professional or amateur, prior to 1999.
Significance
By 2004, robotic observations accounted for an overwhelming
percentage of the published scientific information on asteroid
orbits and discoveries, variable star studies, supernova light
curves and discoveries, and comet orbits.
Issue #94
