Based on our experiences on developing software for Antarctica Survey Telescope (AST3), we propose a software standard of controlling and operating system for real unattended robotic observatories. Besides automaticity, this standard addresses special issues of high availability, fault-tolerance, power efficiency, etc., which are much less important for matured observatories but become crucial for real unattended observatories, e.g., Antarctica sites or space telescope. Our recommended standard defines sets of common instructions to operate all the facilities of an observatory. For each instruction, the standard specifies its function, how it responses when a hardware or software exception arises and informs users in detail. Then it specifies an application programming interface (API) so that user programs know how to call it to execute a certain operation. Finally, we propose feasible inter process communication protocols for the API implementation as well as managing the special redundant hardware. By calling the universal API users can easily develop their own software to control and operate an astronomical observatory robustly and fully automatically with minimum human intervention, even if their devices are highly customized.
The seeing at Dome A, Antarctica is expected to be similar to the superb seeing at Dome C, a median of about 0:003. However, there has not been direct night seeing measurement yet, because unattended DIMM (Differential Image Motion Monitor) is hard to be operated automatically over the winter at Dome A. To solve this problem, we propose an automatic DIMM for Kunlun Station at Dome A, named KLDIMM. Here we will present the hardware design, software system and results of cold laboratory test. This system will be tested at sites in China and calibrated to other DIMMs, then installed on an 8-m tall customized tower at Dome A in January 2019.
Kunlun Cloud and Aurora Monitor (KLCAM) is an all-sky camera with intensive thermal control designs specifically for the harsh environment at Dome A, Antarctica. The prototype of KLCAM was installed at Kunlun Station, Dome A in early 2017 and has worked under unattended condition non-stop through the polar nights successfully. KLCAM collects data for site testing as well as providing real-time observing conditions for the operation of the Antarctic Survey Telescope (AST3).
We present a new application of frame transfer Charge-Coupled Device (CCD) on measuring astronomical seeing. If a telescope is equipped with a shutterless, frame transfer CCD camera, a bright star will generate a trail during the frame transfer phase. Because the transfer is very fast, the trail is a series of short exposures (about 1 ms) of the target star. Therefore the centroid is jittery due to atmospheric turbulence, and the amplitude can be utilized to derive astronomical seeing. We present the preliminary results from STA1600FT CCD on the second Antarctic Survey Telescope (AST3) tested in China. The trail seeing moderately agrees with the simultaneous DIMM seeing.
We have developed a specialized software package, called ast3suite, to achieve the remote control and automatic sky survey for AST3 (Antarctic Survey Telescope) from scratch. It includes several daemon servers and many basic commands. Each program does only one single task, and they work together to make AST3 a robotic telescope. A survey script calls basic commands to carry out automatic sky survey. Ast3suite was carefully tested in Mohe, China in 2013 and has been used at Dome, Antarctica in 2015 and 2016 with the real hardware for practical sky survey. Both test results and practical using showed that ast3suite had worked very well without any manual auxiliary as we expected.
We have successfully operated the AST3 telescope remotely as well as robotically for time-domain sky survey in 2015 and 2016. We have set up a real-time system to support the operation of the unattended telescope, monitoring the status of all instruments as well as the weather conditions. The weather tower also provides valuable information of the site at the highest plateau in Antarctica, demonstrating the extremely stable atmosphere above the ground and implying excellent seeing at Dome A.
The first of the trio Antarctic Survey Telescopes (AST3) has been deployed to Dome A, Antarctica in January
2012. This largest optical survey telescope in Antarctica is equipped with a 10k × 10k CCD. The huge amount of
data, limited satellite communication bandwidth, low temperature, low pressure and limited energy supply all
place challenges to the control and operation of the telescope. We have developed both the hardware and software
systems to operate the unattended telescope and carry out the survey automatically. Our systems include the
main survey control, data storage, real-time pipeline, and database, for all of which we have dealt with various
technical difficulties. These include developing customized computer systems and data storage arrays working at
the harsh environment, temperature control for the disk arrays, automatic and fast data reduction in real-time,
and building robust database system.
The FPGA with Avalon Bus architecture and Nios soft-core processor developed by Altera Corporation is an advanced embedded solution for control and interface systems. A CCD data acquisition system with an Ethernet terminal port based on the TCP/IP protocol is implemented in NAOC, which is composed of a piece of interface board with an Altera's FPGA, 32MB SDRAM and some other accessory devices integrated on it, and two packages of control software used in the Nios II embedded processor and the remote host PC respectively. The system is used to replace a 7200 series image acquisition card which is inserted in a control and data acquisition PC, and to download commands to an existing CCD camera and collect image data from the camera to the PC. The embedded chip in the system is a Cyclone FPGA with a configurable Nios II soft-core processor. Hardware structure of the system, configuration for the embedded soft-core processor, and peripherals of the processor in the PFGA are described. The C program run in the Nios II embedded system is built in the Nios II IDE kits and the C++ program used in the PC is developed in the Microsoft's Visual C++ environment. Some key techniques in design and implementation of the C and VC++ programs are presented, including the downloading of the camera commands, initialization of the camera, DMA control, TCP/IP communication and UDP data uploading.
KEYWORDS: CCD cameras, Data processing, Cameras, Field programmable gate arrays, Image processing, Data acquisition, Solar telescopes, Astronomy, Magnetism, Solar processes
For astronomical observations, there are many kinds of CCD cameras for different scientific purposes. Sometimes, this even happens in one telescope. Traditionally, a CCD camera has an individual image grabber, data process unit, and corresponding control computer. Consequently, this brings some inconvenience and problems not only to the system management but also to the updating of the system. This paper presents a resolution to this problem for the Multi-Channel Solar Telescope (MCST). All CCD cameras are connected in an Ethernet through an Ethernet interface. A server is needed to send commands to all cameras and transfer data through TCP/IP. Each CCD camera has an embedded system to control the camera, receive commands from the server and signals from the camera, process, and store the data. This paper describes the design of an Ethernet controlled camera. The camera is PULNIX TM1010, which is controlled by an Altera embedded system by Cyclone EP1C20F400C7 FPGA, which embedded with a Nios processor.
The first astronomical space telescope of China, the Space Solar Telescope (SST), of which the main optical telescope's diameter is one meter, is now being built in the National Astronomical Observatories, Chinese Academy of Sciences (NAOC). In order to obtain high precision data of solar magnetic field, long time exposure is required. Therefore, the correlation tracker technology is applied to keep the images stable during the long exposure and to ensure a high spatial resolution. In this paper, we will analyze the accuracy of the correlation tracker of SST by simulating the high-resolution ground-based observations.
By our analyses, it is found that at the spatial scale of 0.1", an accuracy of about 0.3-pixel can be achieved when using cross-correlation method together with 25-point parabolic fitting. The result is better than using only cross-correlation method. And after the quantification effect being computed, Our preliminary result shows that it will get similar result by using either higher or lower level quantification. That is, precision acquired by using 16bit quantification cannot reach much higher than by 1bit in the SST/CT.
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