The site testing shows that Antarctic Dome A is one of the best site on earth for astronomical observations, for wavelength ranging from visible to infrared and sub-millimeter. Continuous observation for nearly four months in polar nights makes Dome A quite suitable for time domain astronomy. In the past decade CCAA already led a series of Antarctic astronomy activities and telescope projects which will be introduced in this paper. The first generation telescope is Chinese Small Telescope Array known as CSTAR, which was composed of four identical telescopes with 145mm entrance pupil, 20 square degrees FOV and different filters, all pointing to the celestial South Point, mainly used for variable stars detection and site testing. The telescope was deployed in Dome A in Jan. 2008, and followed by automatic observations for four consecutive winters. Three Antarctic Survey Telescopes (AST3) is the second generation telescope capable of pointing and tracking in very low temperature, with 500mm entrance pupil, 8.5 square degree FOV. AST3-1 and AST3-2 were respectively mounted on Dome A in Jan. 2012 and 2015, fully remotely controlled for supernovae survey and exoplanets searching. In Aug. 2017, AST3-2 successfully detected the optical counterpart of LIGO Source GW 170817. Now AST3-3 is under development for both optical and near infrared sky survey by matching different cameras. Based on the experience of the above smaller sized optical telescopes, the 2.5m Kunlun Dark Universe Survey Telescope (KDUST) was proposed for high resolution imaging over wide field of view. Currently the KDUST proposal was submitted to the government and waiting for project review.
AST3-NIR is a new infrared camera for deployment with the AST3-3 wide-field survey telescope to Dome A on the Antarctic plateau. This project is designed to take advantage of the low Antarctic infrared sky thermal background (particularly within the K<sub>dark</sub> near infrared atmospheric window at 2.4 μm) and the long Antarctic nights to provide high sensitivity temporal data from astronomical sources. The data collected from the Kunlun Infrared Sky Survey (KISS) will be used to conduct a range of astronomical science cases including the study of supernovae, exo-planets, variable stars, and the cosmic infrared background.
The Antarctic Survey Telescope-AST3 consists of three optical telescopes with 680mm primary mirror and 8 square degree field of view, mainly for observations of supernovas and extrasolar planets searching from Antarctic Dome A. The first two AST3 telescopes (AST3-1 and AST3-2) were successfully installed on Dome A by Chinese expedition team in Jan. 2012 and Jan. 2015 separately. Multi-anti-frost methods were designed for AST3-2 and the automatic observations are keeping on from March 2016. The best limited magnitude is 19.4m with exposure time 60s in G band. The third AST3 will have switchable interface for both optical camera and near infrared camera optimized for k dark band survey. Now the telescope is under development in NIAOT and the K-band camera is under development in AAO.
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 photon transfer curve (PTC, variance vs. signal level) is a commonly used and effective tool in characterizing CCD performance. It is theoretically linear in the range where photon shot noise dominates, and its slope is utilized to derive the gain of the CCD. However, recent researches on different CCDs have revealed that the variance progressively drops at high signal levels, while the linearity shown by signal versus exposure time is still excellent and unaffected. On the other hand, bright stars are found to exhibit fatter point spread function (PSF). Both nonlinear PTC and the brighter-fatter effect are regarded as the result of spreading of charges between pixels, an interaction progress increasing with signal level. In this work we investigate the nonlinear PTC based on the images with a STA1600FT CCD camera, whose PTC starts to become nonlinear at about 1/3 full well. To explain the phenomenon, we present a model to characterize the charge-sharing PSF. This signal-dependent PSF can be derived from flat-field frames, and allow us to quantify the effects on photometry and measured shape of stars. This effect is essentially critical for projects requiring accurate photometry and shape parameters.
We have developed a new method to correct dark current at relatively high temperatures for Charge-Coupled Device (CCD) images when dark frames cannot be obtained on the telescope. For images taken with the Antarctic Survey Telescopes (AST3) in 2012, due to the low cooling efficiency, the median CCD temperature was -46°C, resulting in a high dark current level of about 3e−/pix/sec, even comparable to the sky brightness (10e−/pix/sec). If not corrected, the nonuniformity of the dark current could even overweight the photon noise of the sky background. However, dark frames could not be obtained during the observing season because the camera was operated in frame-transfer mode without a shutter, and the telescope was unattended in winter. Here we present an alternative, but simple and effective method to derive the dark current frame from the scientific images. Then we can scale this dark frame to the temperature at which the scientific images were taken, and apply the dark frame corrections to the scientific images. We have applied this method to the AST3 data, and demonstrated that it can reduce the noise to a level roughly as low as the photon noise of the sky brightness, solving the high noise problem and improving the photometric precision. This method will also be helpful for other projects that suffer from similar issues.
The AST3 project consists of three large field of view survey telescopes with 680mm primary mirror, mainly for observations of supernovas and extrasolar planets searching from Antarctic Dome A where is very likely to be the best astronomical site on earth for astronomical observations from optical wavelength to thermal infrared and beyond, according to the four years site testing works by CCAA, UNSW and PRIC. The first AST3 was mounted on Dome A in Jan. 2012 and automatically run from March to May 2012. Based on the onsite winterization performance of the first AST3, some improvements such as the usage of high resolution encoders, defrosting method, better thermal control and easier onsite assembly et al were done for the second one. The winterization observation of AST3-2 in Mohe was carried on from Nov. 2013 to Apr. 2014, where is the most northern and coldest part of China with the lowest temperature around -50°. The technical modifications and testing observation results will be given in this paper. The third AST3 will be optimized from optical to thermal infrared aiming diffraction limited imaging with K band. Thus the whole AST3 project will be a good test bench for the development of future larger aperture optical/infrared Antarctic telescopes such as the proposed 2.5m Kunlun Dark Universe Survey Telescope project.
Chinese Antarctic Observatory has been listed as National large research infrastructure during twelfth five-year plan. Kunlun Dark Universe Survey Telescope, one of two major facility of Chinese Antarctic Observatory, is a 2.5-meter optic/infrared telescope and will be built at the Chinese Antarctic Kunlun Station. It is intended to take advantage of the exceptional seeing conditions, as well as the low temperature reducing background for infrared observations. KDUST will adopt an innovative optical system, which can deliver very good image quality over a 2 square degree flat field of view. All of parts of it have been designed carefully to endure the extremely harsh environment. KDUST will be perched on a 14.5-meter-high tower to lift it above the turbulence layer. In this paper, preliminary design and key technology pre-research of KDUST will be introduced.
A 10k x 10k single-chip CCD camera was installed on the first Antarctic Survey Telescope (AST3-1) at Dome A,
Antarctica in January 2012. The pixel size is 9 μm, corresponding to 1 arcsec on the focal plane. The CCD runs
without shutter but in frame transfer mode, and is cooled by thermoelectric cooler (TEC) to take advantage
of the low air temperature at Dome A. We tested the performance of the camera in detail, including the gain,
linearity, readout noise, dark current, charge transfer efficiency, etc. As this camera is designed to work at Dome
A, where the lowest air temperature could go down to −80°C in winter, we tested to cool not only the CCD
chip but also the controller which usually is operated at normal temperatures for ground-based telescopes. We
found that the performance of the camera changes a little when the controller is cooled.
The preliminary site testing carried out since the beginning of 2008 shows the Antarctic Dome A is very likely to be the
best astronomical site on earth even better than Dome C and suitable for observations ranging from optical wavelength to
infrared and sub-millimeter. After the Chinese Small Telescope Array (CSTAR) which is composed of four small fixed
telescopes with diameter of 145mm and mounted on Dome A in 2008 for site testing and variable star monitor, three
Antarctic Survey Telescopes (AST3) were proposed for observations of supernovas and extrasolar planets searching.
AST3 is composed of 3 large field of view catadioptric telescopes with 500mm entrance diameter and G, R, I filter for
each. The telescopes can point and track autonomously along with a light and foldable dome to keep the snow and icing
build up. A precise auto-focusing mechanism is designed to make the telescope work at the right focus under large
temperature difference. The control and tracking components and assembly were successfully tested at from normal
temperature down to -80 Celsius degree. Testing observations of the first AST3 showed it can deliver good and uniform
images over the field of 8 square degrees. The first telescope was successfully mounted on Dome A in Jan. 2012 and the
automatic observations were started from Mar. 2012.
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.
Nigel is a fiber-fed UV/visible grating spectrograph with a thermoelectrically-cooled 256×1024 pixel CCD camera,
designed to measure the twilight and night sky brightness from 300nm to 850 nm. Nigel has three pairs of fibers,
each with a field-of-view with an angular diameter of 25 degrees, pointing in three fixed positions towards the
sky. The bare fibers are exposed to the sky with no additional optics. The instrument was deployed at Dome A,
Antarctica in January 2009 as part of the PLATO (PLATeau Observatory) robotic observatory. During the 2009
winter, Nigel made approximately six months of continuous observations of the sky, with typically 104 deadtime
between exposures. The resulting spectra provide quantitative information on the sky brightness, the auroral
contribution, and the water vapour content of the atmosphere. We present details of the design, construction
and calibration of the Nigel spectrometer, as well some sample spectra from a preliminary analysis.
Prelimenary site testing led by Chinese Center of Antarctic Astronomy (CCAA) shows that the highest point of the
Antarctic Plateau Dome A has very clear sky, good seeing, slow wind, low boundary layer and very low precipitable
water vapour which make it the best site on earth for optical/IR and sub-mm observations. Chinese Small Telescope
ARray (CSTAR) was installed at Dome A in 2008 and have automatically observed for about 3 antarctic winters. The
three Antarctic Schmidt telescopes(AST3) with entrance pupil diameter 500mm are the second antarctic project
proposed by CCAA and the first AST are being constructed in NIAOT now which is planned to be mounted on Dome A
at the beginning of 2011. All the tracking components were tested in the low temperature chamber and an adaptive
defrosting method is designed to prevent the frost building up on the schmidt plate.
Snodar is a high resolution acoustic radar designed specifically for profiling the atmospheric boundary layer on the high
Antarctic plateau. Snodar profiles the atmospheric temperature structure function constant to a vertical resolution of 1 m
or better with a minimum sample height of 8 m. The maximum sampling height is dependent on atmospheric conditions
but is typically at least 100 m. Snodar uses a unique in-situ intensity calibration method that allows the instrument to be
autonomously recalibrated throughout the year. The instrument is initially intensity calibrated against tower-mounted
differential microthermal sensors. A calibration sphere is located in the near-field of the antenna to provide a fixed echo
of known intensity, allowing the instrument to be continuously re-calibrated once deployed. This allows snow
accumulation, transducer wear and system changes due to temperature to be monitored. Year-round power and
communications are provided by the PLATO facility. This allows processed data to be downloaded every 6 hours while
raw data is stored on-site for collection the following summer. Over 4 million processed samples have been downloaded
through PLATO to date. We present signal attenuation from accumulation of snow and ice on Snodar's parabolic
reflector during the 2009 at Dome A.
The high altitude Antarctic sites of Dome A and the South Pole offer intriguing locations for future large scale optical
astronomical Observatories. The Gattini project was created to measure the optical sky brightness, large area cloud cover
and aurora of the winter-time sky above such high altitude Antarctic sites. The Gattini- DomeA camera was installed on
the PLATO instrument module as part of the Chinese-led traverse to the highest point on the Antarctic plateau in January
2008. This single automated wide field camera contains a suite of Bessel photometric filters (B, V, R) and a long-pass
red filter for the detection and monitoring of OH emission. We have in hand one complete winter-time dataset (2009)
from the camera that was recently returned in April 2010.
The Gattini-South Pole UV camera is a wide-field optical camera that in 2011 will measure for the first time the UV
properties of the winter-time sky above the South Pole dark sector. This unique dataset will consist of frequent images
taken in both broadband U and B filters in addition to high resolution (R~5000) long slit spectroscopy over a narrow
bandwidth of the central field. The camera is a proof of concept for the 2m-class Antarctic Cosmic Web Imager
telescope, a dedicated experiment to directly detect and map the redshifted lyman alpha fluorescence or Cosmic Web
emission we believe possible due to the unique geographical qualities of the site.
We present the current status of both projects.
For continuous observation at locations that are inhospitable for humans, the desirability of autonomous observatories is
self evident. PLATO, the 'PLATeau Observatory' was designed to host an easily configurable instrument suite in the
extremely cold conditions on the Antarctic plateau, and can provide up to 1 kW of power for the instruments. Powered
by jet fuel and the Sun, PLATO and its instruments have been taking nearly uninterrupted astronomical science and sitetesting
data at Dome A, the coldest, highest and driest location<sup>1</sup> on the Antarctic Plateau, since their deployment by the
24th Chinese expedition team in January 2008. At the time of writing, PLATO has delivered a total uptime of 730 days.
Following a servicing mission by the 25th Chinese expedition team in 2008-9, PLATO has achieved 100% up-time (520
days) and has been in continuous contact with the rest of the world via its Iridium satellite modems. This paper discusses
the performance of the observatory itself, assesses the sources of energy and dissects how the energy is divided between
the core observatory functions of instrument power, heating, control and communication.
Pre-HEAT is a 20 cm aperture submillimeter-wave telescope with a 660 GHz (450 micron) Schottky diode heterodyne
receiver and digital FFT spectrometer for the Plateau Observatory (PLATO) developed by the University of New South
Wales. In January 2008 it was deployed to Dome A, the summit of the Antarctic plateau, as part of a scientific traverse
led by the Polar Research Institute of China and the Chinese Academy of Sciences. Dome A may be one of the best sites
in the world for ground based Terahertz astronomy, based on the exceptionally cold, dry and stable conditions which
prevail there. Pre-HEAT is measuring the 450 micron sky opacity at Dome A and mapping the Galactic Plane in the
<sup>13</sup>CO J=6-5 line, constituting the first submillimeter measurements from Dome A. It is field-testing many of the key
technologies for its namesake -- a successor mission called HEAT: the High Elevation Antarctic Terahertz telescope.
Exciting prospects for submillimeter astronomy from Dome A and the status of Pre-HEAT will be presented.
Over a decade of site testing in Antarctica has shown that both South Pole and Dome C are exceptional sites for
astronomy, with certain atmospheric conditions superior to those at existing mid-latitude sites. However, the highest
point on the Antarctic plateau, Dome A, is expected to experience colder atmospheric temperatures, lower wind speeds,
and a turbulent boundary layer that is confined closer to the ground. The Polar Research Institute of China, who were the
first to visit the Dome A site in January 2005, plan to establish a permanently manned station there within the next
decade. As part of this process they conducted a second expedition to Dome A, arriving via overland traverse in January
2008. This traverse involved the delivery and installation of the PLATeau Observatory (PLATO). PLATO is an
automated self-powered astrophysical site testing observatory, developed by the University of New South Wales. A
number of international institutions have contributed site testing instruments measuring turbulence, optical sky
background, and sub-millimetre transparency. In addition, a set of science instruments are providing wide-field high time
resolution optical photometry and terahertz imaging of the Galaxy. We present here an overview of the PLATO system
design and instrumentation suite.
Chinese first arrived in Antarctic Dome A in Jan. 2005 where is widely predicted to be a better astronomical site than
Dome C where have a median seeing of 0.27arcsec above 30m from the ground. This paper introduces the first Chinese
Antarctic telescope for Dome A (CSTAR) which is composed of four identical telescopes, with entrance pupil 145 mm,
20 square degree FOV and four different filters g, r, i and open band. CSTAR is mainly used for variable stars detection,
measurement of atmosphere extinction, sky background and cloud coverage. Now CSTAR has been successfully
deployed on Antarctic Dome A by the 24th Chinese expedition team in Jan. 2008. It has started automatic observation
since March 20, 2008 and will continuously observe the south area for the whole winter time. The limited magnitude
observed is about 16.5<sup>m</sup> with 20 seconds exposure time. CSTARS's success is a treasurable experience and we can
benefit a lot for our big telescope plans, including our three ongoing 500mm Antarctic Schmidt telescopes (AST3).
We present the Gattini project: a multisite campaign to measure the optical sky properties above the two high altitude
Antarctic astronomical sites of Dome C and Dome A. The Gattini-DomeC project, part of the IRAIT site testing
campaign and ongoing since January 2006, consists of two cameras for the measurement of optical sky brightness, large
area cloud cover and auroral detection above the DomeC site, home of the French-Italian Concordia station. The cameras
are transit in nature and are virtually identical except for the nature of the lenses. The cameras have operated
successfully throughout the past two Antarctic winter seasons and here we present the first results obtained from the
returned 2006 dataset. The Gattini-DomeA project will place a similar site testing facility at the highest point on the
Antarctic plateau, Dome A, with observations commencing in 2008. The project forms a small part of a much larger
venture coordinated by the Polar Research Institute of China as part of the International Polar Year whereby an
automated site testing facility called PLATO will be traversed into the DomeA site. The status of this exciting and
ambitious project with regards to the Gattini-DomeA cameras will be presented.