Guang-yu Zhang

An autonomous observation and control system based on EPICS and RTS2 for Antarctic telescopes

For an unattended telescopes in Antarctic, the remote operation, autonomous observation and control are essential. An EPICS (Experimental Physics and Industrial Control System) and RTS2(Remote Telescope System, 2nd Version) based autonomous observation and control system with remoted operation is introduced in this paper. EPICS is a set of Open Source software tools, libraries and applications developed collaboratively and used worldwide to create distributed soft real-time control systems for scientific instruments while RTS2 is an open source environment for control of a fully autonomous observatory. Using the advantage of EPICS and RTS2 respectively, a combined integrated software framework for autonomous observation and control is established that use RTS2 to fulfill the function of astronomical observation and use EPICS to fulfill the device control of telescope. A command and status interface for EPICS and RTS2 is designed to make the EPICS IOC (Input/Output Controller) components integrate to RTS2 directly. For the specification and requirement of control system of telescope in Antarctic, core components named Executor and Auto-focus for autonomous observation is designed and implemented with remote operation user interface based on Browser-Server mode. The whole system including the telescope is tested in Lijiang Observatory in Yunnan Province for practical observation to complete the autonomous observation and control, including telescope control, camera control, dome control, weather information acquisition with the local and remote operation.

A Study on Generic Models of Control Systems of Large Astronomical Telescopes

The control system is an essential and important part of an astronomical telescope. For large telescopes, an efficient control system is vital for successful observations. In this paper, an exhaustive study of generic models of control systems for large telescopes and a wide range of their common requirements are presented. This paper also discusses a basic hierarchical structure, workflow model, and telescope control model based on object-oriented analysis, as well as the main data flow model of a general purpose telescope. After analysis of these models, a layered and orthogonal architecture, which has a wide range of adaptability, is proposed. The design of a concrete architecture based on the message bus, which is used in the LAMOST (Large Sky Area Multi-Object Fiber Spectroscopy Telescope) project and FAST (The Five-Hundred-Meter Aperture Spherical Radio Telescope) project, is discussed. The design of the control systems proposed in this paper can serve as a useful reference in the construction of large telescopes.

A guiding system of astronomical imaging system for a 1.2-meter-aperture telescope

A guiding system is designed, implemented and tested for our 1.2-meter Quantum-Teleportation Telescope Imaging System, due to the lack of accuracy of its own star tracking function. This paper at first introduces some key technologies of the system including star extraction, offset computation, star tracking, offset conversion and exception handling. The guiding system is implemented as a RTS2 device, and interacts with a guiding CCD and telescope. The workflow control of the guiding process is pushed forward by a finite-state machine. The system is tested in Delingha, Qinghai province. In cloudless condition, the guiding system can work for 15 min continuously, and long-exposure images produced by main CCDs can meet scientific requirements.

Design of observational and control system of imaging system of a 1.2-meter-aperture telescope

The 1.2m Quantum Teleportation Telescope imaging system is a multi-band imaging system with dual channels called ‘red end’ and ‘blue end’. Each channel includes a CCD camera and a filter wheel system, and the blue end contains a focusing system. In order to improve the tracking accuracy, the guiding CCD is designed and deployed. The imaging system studies the mass of the black hole and the structure of AGN by observing the variation of AGN spectral line. In order to improve the observation efficiency, we design and implement a multi-level remote unattended observation and control system. The system adopts the framework of combining RTS2 and EPICS. EPICS is used to realize the individual control of each device. We defined status code and split device properties for debugging purpose or high-level invocating purpose. The EPICS Channel Access is integrated into the RTS2 software and a set of configurations in XML format is designed so that the RTS2 module can find the EPICS application. In the RTS2 layer, we developed a module for the coordinated control of the equipment. The module is responsible for sending instructions to the telescope and the guiding module according to the pre-defined list of observation plans, switching to the corresponding filter, and performing exposure operations. Finally, we developed web service and used web pages as user interface, which makes it convenient for users to control the telescope remotely and complete the observation task.

Scientific CCD camera for CSTAR telescope in Antarctica

A 1K*1K CCD camera is designed, implemented and tested for CSTAR telescope in Antarctica, including its mechanics, CCD controller, power and temperature controller unit. Mechanical and electronic design for low temperature environment is taken into consideration fully. The camera has reliable mechanics and stable electronics performance. The readout noise is as low as 3.99݁ି when the CCD readout speed is 100kpixs/s. We fully tested every part of the camera in a Cryogenic refrigerator (-86 degree centigrade) and proved that our camera has the ability to work in Antarctica for a long term. Finally, the camera was tested on the CSTAR telescopes to take observations and the imaging quality meets requirement.

Electronic control design of a two-channel imaging system of a 1.2-meter-aperture telescope

The Astronomical Imaging System of a 1.2-meter-aperture Telescope is a multi-band imaging system with red and blue channels. The mass and structure of AGN central black hole are studied by observing the change of AGN spectral line. We designed an optical system with dual channels, changing the focal length ratio of telescope from f/8.429 to f/5 through the lens, and divide the optical path into red and blue channels through the beam splitter. The red waveband is 650nm1000nm and the blue waveband is 400nm-650nm. Each channel has a CCD camera. We set up focusing lens before the camera of blue channel to compensate the difference focusing length between red and blue channel after the red channel being focused by adjusting the telescope. For the realization of three groups of broadband photometry and twenty-four groups of narrowband photometry, an automatic filter wheel system is designed to switch the filter. At the same time, in order to reduce the influence of temperature drift of the filter, a constant temperature adjusting system for filter wheel box is carried out. In order to overcome the issue that the telescope itself does not have enough tracking accuracy, a guiding system for the imaging system is designed and implemented. Finally, we designed and implemented a multi-level software control system so that the users can remotely control the telescope.

Automatic focusing system of BSST in Antarctic

Automatic focusing (AF) technology plays an important role in modern astronomical telescopes. Based on the focusing requirement of BSST (Bright Star Survey Telescope) in Antarctic, an AF system is set up. In this design, functions in OpenCV is used to find stars, the algorithm of area, HFD or FWHM are used to degree the focus metric by choosing. Curve fitting method is used to find focus position as the method of camera moving. All these design are suitable for unattended small telescope.

Study on fault diagnose expert system for large astronomy telescope

The development of astronomical techniques and telescopes currently entered a new vigorous period. The telescopes have trends of the giant, complex, diversity of equipment and wide span of control despite of optical, radio space telescopes. That means, for telescope observatory, the control system must have these specifications: flexibility, scalability, distributive, cross-platform and real-time, especially the fault locating and fault processing is more important when fault or exception arise. Through the analysis of the structure of large telescopes, fault diagnosis expert system of large telescope based on the fault tree and distributed log service is given.