E. Bondoux

ASTEP South: an Antarctic Search for Transiting ExoPlanets around the celestial south pole

Context. The Concordia base in Dome C, Antarctica, is an extremely promising site for photometric astronomy due to the 3-month long night during the Antarctic winter, favorable weather conditions, and low scintillation. Aims. The ASTEP project (Antarctic Search for Transiting ExoPlanets) is a pilot project to discover transiting planets and understand the limits of visible photometry from the Concordia site. Methods. ASTEP South is the first phase of the ASTEP project. The instrument is a fixed 10 cm refractor with a 4k × 4k CCD camera in a thermalized box, pointing continuously a 3.88 × 3.88° 2 field of view centered on the celestial south pole. We describe the project and report results of a preliminary data analysis. Results. ASTEP South became fully functional in June 2008 and obtained 1592 hours of data during the 2008 Antarctic winter. The data are of good quality but the analysis has to account for changes in the PSF (point spread function) due to rapid ground seeing variations and instrumental effects. The pointing direction is stable within 10 arcsec on a daily timescale and drifts by only 34 arcsec in 50 days. A truly continuous photometry of bright stars is possible in June (the noon sky background peaks at a magnitude R ≈ 15 arcsec -2 on June 22), but becomes challenging in July (the noon sky background magnitude is R ≈ 12.5 arcsec -2 on July 20). The weather conditions are estimated from the number of stars detected in the field. For the 2008 winter, the statistics are between 56.3% and 68.4% of excellent weather, 17.9% to 30% of veiled weather (when the probable presence of thin clouds implies a lower number of detected stars) and 13.7% of bad weather. Using these results in a probabilistic analysis of transit detection, we show that the detection efficiency of transiting exoplanets in one given field is improved at Dome C compared to a temperate site such as La Silla. For example we estimate that a year-long campaign of 10 cm refractor could reach an efficiency of 69% at Dome C versus 45% at La Silla for detecting 2-day period giant planets around target stars from magnitude 10 to 15. The detection efficiency decreases for planets with longer orbital periods, but in relative sense it is even more favorable to Dome C. Conclusions. This shows the high potential of Dome C for photometry and future planet discoveries.

ASTEP 400: a telescope designed for exoplanet transit detection from Dome C, Antarctica

The Concordia Base in Dome C, Antarctica, is an extremely promising site for photometric astronomy due to the 3- month long night during the Antarctic winter, favorable weather conditions, and low scintillation. The ASTEP project (Antarctic Search for Transiting ExoPlanets) is a pilot project which seeks to identify transiting planets and understand the limits of visible photometry from this site. ASTEP 400 is an optical 40cm telescope with a field of view of 1° x 1°. The expected photometric sensitivity is 1E-3, per hour for at least 1,000 stars. The optical design guarantees high homogeneity of the PSF sizes in the field of view. The use of carbon fibers in the telescope structure guarantees high stability. The focal optics and the detectors are enclosed in a thermally regulated box which withstands extremely low temperatures. The telescope designed to run at -80°C (-110°F) was set up at Dome C during the southern summer 2009- 2010. It began its nightly observations in March 2010.

ASTEP South: An Antarctic Search for Transiting Planets around the celestial South pole

ASTEP South is the first phase of the ASTEP project (Antarctic Search for Transiting ExoPlanets). The instrument is a fixed 10 cm refractor with a 4kx4k CCD camera in a thermalized box, pointing continuously a 3.88° x 3.88° field of view centered on the celestial South pole. ASTEP South became fully functional in June 2008 and obtained 1592 hours of data during the 2008 Antarctic winter. The data are of good quality but the analysis has to account for changes in the point spread function due to rapid ground seeing variations and instrumental effects. The pointing direction is stable within 10 arcseconds on a daily timescale and drifts by only 34 arcseconds in 50 days. A truly continuous photometry of bright stars is possible in June (the noon sky background peaks at a magnitude R=15 arcsec-2 on June 22), but becomes challenging in July (the noon sky background magnitude is R=12.5 arcsec−2 on July 20). The weather conditions are estimated from the number of stars detected in the field. For the 2008 winter, the statistics are between 56.3 % and 68.4 % of excellent weather, 17.9 % to 30 % of veiled weather and 13.7 % of bad weather. Using these results in a probabilistic analysis of transit detection, we show that the detection efficiency of transiting exoplanets in one given field is improved at Dome C compared to a temperate site such as La Silla. For example we estimate that a year-long campaign of 10 cm refractor could reach an efficiency of 69 % at Dome C versus 45 % at La Silla for detecting 2-day period giant planets around target stars from magnitude 10 to 15. This shows the high potential of Dome C for photometry and future planet discoveries. [Short abstract]

Opening a new window on the southern stars for less money: PAIX the first Antarctica polar mission photometer

In this invited paper, we implement a new way to study the stellar oscillations, pulsations and their evolutionary properties with long uninterrupted and continuous precision observations over 150 days from the ground, and without the regular interruptions imposed by the earth rotation. PAIX–First Robotic Antarctica Polar Mission– gives a new insight to cope with unresolved stellar enigma and stellar oscillation challenges and offers a great opportunity to benefit from an access to the best astronomical site on Earth –DomeC–. The project is made of low cost commercial components, and achieves astrophysical measurement time-series of stellar physics fields, challenging photometry from space that shows large gaps in terms of flexibility during the observing runs, the choice of targets, the repair of failures and the inexorable high costs. PAIX has yet more advantages than space missions in observing in UBV RI bands and then collecting unprecedented simultaneous multicolor light curves of several targets. We give a brief history of the Astronomy in Antarctica and describe the first polar robotized mission PAIX and the outcome of stellar physics from the heart of Antarctica during several polar nights. We briefly discuss our first results and perspectives on the pulsating stars and its evolution from Antarctica, especially the connection between temporal hydrodynamic phenomena and cyclic modulations. Finally, we highlight the impact of PAIX on the stellar physics study and the remaining challenges to successfully accomplish the Universe explorations under extreme conditions.

ASTEP South: A first photometric analysis

The ASTEP project aims at detecting and characterizing transiting planets from Dome C, Antarctica, and qualifying this site for photometry in the visible. The first phase of the project, ASTEP South, is a fixed 10 cm diameter instrument pointing continuously towards the celestial South pole. Observations were made almost continuously during 4 winters, from 2008 to 2011. The point-to-point RMS of 1-day photometric lightcurves can be explained by a combination of expected statistical noises, dominated by the photon noise up to magnitude 14. This RMS is large, from 2.5 mmag at R=8 to 6% at R=14, because of the small size of ASTEP South and the short exposure time (30 s). Statistical noises should be considerably reduced using the large amount of collected data. A 9.9-day period eclipsing binary is detected, with a magnitude R=9.85. The 2-season lightcurve folded in phase and binned into 1000 points has a RMS of 1.09 mmag, for an expected photon noise of 0.29 mmag. The use of the 4 seasons of data with a better detrending algorithm should yield a sub-millimagnitude precision for this folded lightcurve. Radial velocity follow-up observations are conducted and reveal a F-M binary system. The detection of this 9.9-day period system with a small instrument such as ASTEP South and the precision of the folded lightcurve show the quality of Dome C for continuous photometric observations, and its potential for the detection of planets with orbital period longer than those usually detected from the ground.

Four winters of photometry with ASTEP South at Dome C, Antarctica

Dome C in Antarctica is a promising site for photometric observations thanks to the continuous night during the Antarctic winter and favorable weather conditions. We developed instruments to assess the quality of this site for photometry in the visible and to detect and characterize variable objects through the Antarctic Search for Transiting ExoPlanets (ASTEP) project. We present the full analysis of four winters of data collected with ASTEP South, a 10 cm refractor pointing continuously toward the celestial south pole. We improved the instrument over the years and developed specific data reduction methods. We achieved nearly continuous observations over the winters. We measure an average sky background of 20 mag arcsec

Six winters of photometry from Dome C, Antarctica: challenges, improvements, and results from the ASTEP experiment

^{-2}

The LUCAS program: detecting vegetation and traces of life in the Earthshine

in the 579-642 nm bandpass. We built the lightcurves of 6000 stars and developed a model to infer the photometric quality of Dome C from the lightcurves themselves. The weather is photometric

Photometric quality of Dome C for the winter 2008 from ASTEP South

67.1\pm4.2

The LUCAS experiment: Spectroscopy of Earthshine in Antarctica for detection of life

% of the time and veiled