We present the design, commissioning, and initial results of the Green Bank Earth Station (GBES), a RadioAstron data downlink station located at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia. The GBES uses the modernized and refurbished NRAO 140ft telescope. Antenna optics were refurbished with new motors and drives fitted to the secondary mirror positioning system, and the deformable subreflector was refurbished with a new digital controller and new actuators. A new monitor and control system was developed for the 140ft and is based on that of the Green Bank Telescope (GBT), allowing satellite tracking via a simple scheduling block. Tools were developed to automate antenna pointing during tracking. Data from the antenna control systems and logs are retained and delivered with the science and telemetry data for processing at the Astro Space Center (ASC) of the Lebedev Physical Institute (LPI) of the Russian Academy of Sciences and the mission control centre, Lavochkin Association.
The National Radio Astronomy Observatory Green Bank Telescope (GBT), the world's largest fully steerable telescope, is now undergoing commissioning and early scientific operation. The GBT has many innovative design features that advance imaging quality, sensitivity, and versatility. These include an unblocked aperture, an active surface, and a six-degree of freedom Gregorian subreflector. The GBT has an advanced laser rangefinder metrology system, which will measure the position of the active surface panels, and also guide the precision pointing of the telescope. Early commissioning results have confirmed the performance of the telescope, and exciting scientific discoveries are already being made. This paper describes the various features of the telescope in more detail, and presents the latest results.
The NRAO-Green Bank Telescope, the world's largest, fully steerable radio telescope, is now in routine use by visiting astronomers. The telescope is unique because of its offset optical design and its complex suite of state-of-the-art instruments. To exploit the full powers of the system, observers and staff members require intuitive user interfaces. We will demonstrate one of the various graphical user interfaces that have been built for the telescope. The interface, written in Tcl/Tk and used predominately by staff engineers, telescope operators, and programmers, is designed for very detailed monitoring and debugging of telescope components. The interface lies on top of an object-oriented control system that provides the GUI builder a set of software methods that is the same for every GBT device, from receivers to detectors. The uniform set of methods reduces the work normally needed in creating a high-level user interface and allows for the creation of interfaces in a range of programming languages.