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Due to its superb seeing conditions, the Antarctica plateau is widely considered to be an excellent astronomical site. The long periods of uninterrupted darkness at polar sites such as Dome A provide a possibility of continuous observation for more than three months, which is quite suitable for time-domain astronomy. Since 2008, several wide-field optical photometric telescopes, including Chinese Small Telescope ARray (CSTAR), two of the Three Antarctic Survey Telescopes (AST3), have been deployed on Dome A. Science with these telescopes covers variable stars, supernovas, exoplanets, etc. For the remoteness of the Antarctic plateau, these telescopes are designed to observe autonomously and operate remotely via satellite communication. As for future plan, Kunlun Dark Universe Survey Telescope (KDUST), a 2.5-meter optic/infrared telescope, is being proposed as one of the two major facilities of Chinese Antarctic Observatory. more...

International audience; The CHinense Exoplanet Searching Program from Antarctica is a ground-based wide-field photometric survey using the AST3 and CSTAR telescopes located at Dome A, Antarctica. Blessed with the unparalleled observing conditions on the highest point of the Antarctic plateau, three remotely controlled, fully automatic telescopes (AST3-I, AST3-II, and CSTAR-II) carried out continuous high-precision photometric surveys through the polar nights of 2016 and 2017. During the observing seasons of 2016, a total of 26,578 light curves were obtained for stars within the area of the southern continuous viewing zone of TESS, covering an i-band magnitude range from 7.5 to 15. At m i = 10, photometric precision reaches ∼2 mmag, allowing possible discoveries of sub-Jupiter-size exoplanets. Here we report 20 stellar flares with i-band energies larger than 1034 erg detected in the 2016 data set of AST3-II, all from different sources. We model the stellar flares and calculate the durations, amplitudes, energies, and skewnesses. The flare properties and the stellar properties of their sources are presented in this work. more...

Located at Dome A, the highest point of the Antarctic plateau, the Chinese Kunlun station is considered to be one of the best ground-based photometric sites because of its extremely cold, dry, and stable atmosphere(Saunders et al. 2009). A target can be monitored from there for over 40 days without diurnal interruption during a polar winter. This makes Kunlun station a perfect site to search for short-period transiting exoplanets. Since 2008, an observatory has been built at Kunlun station and three telescopes are working there. Using these telescopes, the AST3 project has been carried out over the last six years with a search for transiting exoplanets as one of its key programs (CHESPA). In the austral winters of 2016 and 2017, a set of target fields in the Southern CVZ of TESS (Ricker et al. 2009) were monitored by the AST3-II telescope. In this paper, we introduce the CHESPA and present the first data release containing photometry of 26,578 bright stars (m_i < 15). The best photometric precision at the optimum magnitude for the survey is around 2 mmag. To demonstrate the data quality, we also present a catalog of 221 variables with a brightness variation greater than 5 mmag from the 2016 data. Among these variables, 179 are newly identified periodic variables not listed in the AAVSO databasea), and 67 are listed in the Candidate Target List(Stassun et al. 2017). These variables will require careful attention to avoid false-positive signals when searching for transiting exoplanets. Dozens of new transiting exoplanet candidates will be also released in a subsequent paper(Zhang et al. 2018b)., 42 pages, 23 figures and 4 tables, ApJS accepted more...

We report first results from the CHinese Exoplanet Searching Program from Antarctica (CHESPA)---a wide-field high-resolution photometric survey for transiting exoplanets carried out using telescopes of the AST3 (Antarctic Survey Telescopes times 3) project. There are now three telescopes (AST3-I, AST3-II, and CSTAR-II) operating at Dome A---the highest point on the Antarctic Plateau---in a fully automatic and remote mode to exploit the superb observing conditions of the site, and its long and uninterrupted polar nights. The search for transiting exoplanets is one of the key projects for AST3. During the Austral winters of 2016 and 2017 we used the AST3-II telescope to survey a set of target fields near the southern ecliptic pole, falling within the continuous viewing zone of the TESS mission \citep{Ricker10}. The first data release of the 2016 data, including images, catalogs and lightcurves of 26578 bright stars ($7.5\le i \le15$) was presented in \citet{Zhang18}. The best precision, as measured by the RMS of the lightcurves at the optimum magnitude of the survey ($i=10$), is around 2\,mmag. We detect 222 objects with plausible transit signals from these data, 116 of which are plausible transiting exoplanet candidates according to their stellar properties as given by the TESS Input Catalog \citep{Stassun17}, Gaia DR2 \citep{Gaia18} and TESS-HERMES spectroscopy \citep{Sharma18}. With the first data release from TESS expected in late 2018, this candidate list will be a timely for improving the rejection of potential false positives., 49 pages, 23 figures, 3 tables more...

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. more...

Transiting extrasolar planets (exoplanets), especially those orbiting bright stars, are desired for study of the diversity of planetary compositions, internal structures and atmospheres beyond our solar system. Dome A at Antarctica is a promising site for planetary transit surveys, where the continuous darkness and the large clear-sky fraction in the winter months greatly enhance the detection efficiency. The Chinese Small Telescope ARray and the Antarctic Survey Telescopes are the first facilities that have been operated at Dome A for use in exoplanet surveys. To increase the sky coverage, a low-temperature-resistant wide-field robotic telescope, named the bright star survey telescope (BSST), has been developed to join the ongoing planetary transit survey in Antarctica. The BSST has an aperture size of 300 mm and is equipped with a large-frame 4k x 4k CCD camera to receive starlight from a 3.degrees 4 x 3.degrees 4 field of view. The BSST was operated at Lijiang observatory in April and May 2015 for a test run. Photometric precision of 3.5 mmag was achieved for stars with V similar to 11 mag using 75 s exposures. The transiting events of two Jupiter-size exoplanets, HAT-P-3b and HAT-P-12b, were observed on May 10 and May 20, 2015, respectively. more...

International audience; From the experiences learned in three decades of exoplanet search, wide-field transit surveys have proven to be one of the most effective ways to detect exoplanets. Wide field of view, however, suffers from high false-positive rates caused by blended eclipsing binaries. The chromaticity in eclipse depth is an effective feature to distinguish low-depth eclipsing binaries from transiting exoplanets, making multiple-band photometry follow-up advantageous before a target is passed onto more expensive spectroscopic follow-up. Moreover, a multiple-band photometric survey is itself a powerful method to find and vet planetary candidates and narrow down the candidate list of high-priority targets. In this work, we report the first results of a dual-band (Sloan-g and -i) wide-field photometry survey—the Chinese Small Telescope ARray II (CSTAR-II), an updated version of the original CSTAR. As a key component of the Chinese Exoplanet Searching Program from Antarctica, CSTAR-II has been tested thoroughly at a remote arctic site near Mohe during the winter of 2014. In total, 13,531 light curves with the best overall photometric precision of ∼3 mmag were extracted from 7721 stars in the Sloan-g and -i bands. Using a robust method, we have detected 63 variables, of which 48 are newly discovered. The dual-band photometric results as well as the stellar properties of the detected sources are provided in this work. more...

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. more...

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. more...

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. more...

The first Three Antarctic Survey Telescope (AST3-1), a 50/68cm Schmidt-like equatorial-mount telescope, is the first automated Chinese telescope operating on the Antarctic plateau. It is planned to be in operations at Dome A, the highest peak on the Antarctic plateau, in 2012. The telescope is unmanned during night-time operations in the Austral winter. The telescope optics and mechanics, as well as the motors and position sensors, are exposed to a very harsh environment. The mechanics is enclosed with a foldable tent-like dome to prevent snow, diamond dust and ice. While the drive boxes, most circuit, power supply and computers are located inside the warm instrumental cabin. This article describes the challenges the telescope control system encountered in night-time operations, such as the power supply limit, the harsh meteorological condition, unattended testing, automatic operation, remote control and telemetry, etc. Some solutions are also discussed in this paper, which are applied on the AST3-1 and waiting for validation. AST3-1 is also an exploration of a larger telescope on the Antarctic. more...