PLATO operation and Dome A site properties. Michael Ashley / University of New South Wales

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1 PLATO operation and Dome A site properties Michael Ashley / University of New South Wales Image: The Galactic Centre and aurora from the South Pole, Daniel Luong-Van, 2010

2 Collaborators Anna Moore, Tony Travouillon California Institute of Technology, USA Jingyao Hu, Zhaoji Jiang, Xu Zhou National Astronomical Observatory of China, China Xiangqun Cui, Xuefei Gong, Xiangyan Yuan Nanjing Institute of Astronomical Optics Technology, China Longlong Feng, Zhenxi Zhu, Ji Yang, Xu-Guo Zhang, Jun Yan Purple Mountain Observatory, China Yuansheng Li, Weijia Qin, Bo Sun, Huigen Yang, Zhanhai Zhang Polar Research Institute of China, China Michael Ashley, Colin Bonner, Jon Everett, Shane Hengst, Daniel Luong-Van, John Storey University of New South Wales, Australia John Lawrence Macquarie University and the Australian Astronomical Observatory Graham Allen Solar Mobility, Australia Nicholas Suntzeff, Lifan Wang Texas A&M University, USA Reed Riddle Thirty Meter Telescope Project, USA Zhaohui Shang Tianjin Normal University, China Craig Kulesa, Chris Walker University of Arizona, USA Stuart Bradley University of Auckland, NZ Donald York University of Chicago, USA Carlton Pennypacker University of California at Berkeley, USA Nick Tothill, Mark McCaughrean University of Exeter, UK

3 This talk... Why Antarctica? What is PLATO? PLATO performance Results from Dome A Altitude: 4093m Typical wintertime temperature: -70C Average wind speed: 2.5m/s

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5 Two major problems: (1) turbulence (2) absorption

6 Traditional choices include the west coast of Chile

7 and Mauna Kea Observatory, Hawaii Both these sites have relatively smooth airflow and excellent seeing, but can we do better?

8 + Dome F

9 Observations with a Multi-Aperture Scintillation Sensor and a SODAR at Dome C showed that the free atmosphere starts at ~30m, and the seeing is exceptional; confirmed by DIMM and radiosonde

10 Cumulative seeing probability

11 PILOT telescope overview 2.5 metre optical/infrared telescope Dual role: pathfinder and unique science International project Sited at Concordia Station, Dome C, Antarctica Image: Andrew McGrath

12 So, where is the best site in Antarctica? Dome F

13 PLATO leaving UNSW, Sydney, Australia, November 2007 Green the Engine Module (6 diesel engines, 4000 litres Jet-A1) Yellow the Instrument Module (experiments that need to be warm)

14 Instrument module webcams Iridium antennas Gattini all-sky spare ports Gattini SBC Pre-HEAT CSTAR, SNODAR, Sonics located externally on snow surface

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17 The 2009 Chinese traverse 570 tonnes

18 Dome A traverse 2008 Polar Research Institute of China tractor traverse 2008: 18 expedition members 2 astronomers: Zhou Xu (NAOC), Zhenxi Zhu (PMO) Dome C Dome A 11 Jan 2008 Zhongshan 23 Dec 2007 Images courtesy Li Yuansheng, PRIC

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20 PLATO on its two week trip to Dome A, December 2007

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23 PLATO at Dome A, January 2010

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26 Things that have gone wrong In the first year (2008), we stopped after 204 days due to an exhaust leak. A solar panel power converter failed in Three DC-DC converters have failed. Various temperature and voltage sensors have failed. Several alternators have failed catastrophically due to design faults. The Iridium satellite system is unreliable (typical downtime of 30 minutes/month, with one outage of two days). Some experiments have had trouble with icing.

27 Atmospheric turbulence (Snodar x 2 in 2009; Snodar x1 in 2010; Shabar) Boundary layer height, distribution and variability. Sky emission and transparency (CSTAR, Gattini, Nigel, HRCAM) Visible sky background (BVR and OH filters) versus sun/moon elevation; auroral intensity and distribution; spectra of the sky background (lowresolution (2.5nm) nm); all-sky colour images. Precision, continuous, optical photometry (CSTAR) THz sky opacity (Pre-HEAT (2008), FTS (2010)) Transparency and noise in the terahertz region. Cloud (Gattini, CSTAR, HRCAM, webcams) Cloud cover statistics and distribution. PLATO science

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29 CSTAR: four co-mounted Schmidt telescopes - 145mm aperture, f/ x 4.5 degree field of view - g, r, i, and open, filters - 1K x 1K CCDs - pointing at the South Celestial Pole, no tracking - 360GB of data obtained during 2008; over 700GB during three papers published in 2010

30 Pre-HEAT 20cm off-axis parabola 661GHz (450 micron) Schottky diode heterodyne receiver Measures sub-mm sky transparency, and hence PWV (Precipitable Water Vapour)

31 Gattini wide-field multi-filter optical camera PI: Anna Moore, Caltech > 1.2TB of images have been obtained in 2009/2010.

32 Gattini thumbnails The raw images from the Gattini camera are 2048x2048 pixels (8MB). We transfer 256x256 thumbnails (50KB) of occasional images. We send back all the pixels within small apertures around 40 stars.

33 igel s bob

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36 Typical spectrum of the twilight sky from Dome A, with approximate flux calibration. A number of absorption bands are visible: A (759.4 nm) and B (686.7 nm) due to molecular oxygen, C (656.3 nm) due to hydrogen, and G (430.8 nm) from iron. It is noteworthy that the water vapour absorption features at 730 and 820 nm normally quite deep at temperate-latitude observatories are almost entirely absent at Dome A, due to the exceedingly low water vapour content of the atmosphere.

37 Gattini-Nigel: a bright aurora

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42 SNODAR

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44 Snodar data; each plot 24 hours; 0-120metres

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46 Cumulative histogram of the boundary layer height Dome A comparison with Dome C Cumulative probability distributions of the boundary layer height over Dome A during 2009 (solid line), and Dome C during 2005 (dashed line). Data for Dome C are from [10]. Median boundary layer heights for Dome A and Dome C are 13.9 m and 33 m

47 FTS (Fourier Transform Spectrometer) Measures the atmospheric transmission from 0.75 to 15 THz, i.e., from 20 microns to 400 microns. Uses ambient temperature DLATGS (deuterated L-anine doped triglycene suplhate) pyroelectric detectors. Sheng-Cai Shi, Q. J. Yao, X. X. Li, X. G., Zhang, Z. H. Lin, K. M. Zhou, Q. G. Huang, J. Yang (PMO); Scott Paine, Q. Z. Zhang (SAO); H. Matsuo (NAOJ)

48 Moonrise at Dome A April 2008 Webca ms

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54 HRCAM all-sky image, showing the traverse leaving Dome A, January 2010

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56 HRCAM images 2010

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58 HRCAM images taken last night, showing the coronal mass ejection of 2 August 2010 reaching the earth

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61 Where the power came from

62 Where the power went

63 Fuel consumption

64 Atmospheric turbulence (Snodar x 2 in 2009; Snodar x1 in 2010; Shabar) Boundary layer height, distribution and variability. Sky emission and transparency (CSTAR, Gattini, Nigel, HRCAM) Visible sky background (BVR and OH filters) versus sun/moon elevation; auroral intensity and distribution; spectra of the sky background (lowresolution (2.5nm) nm); all-sky colour images. Precision, continuous, optical photometry (CSTAR) THz sky opacity (Pre-HEAT (2008), FTS (2010)) Transparency and noise in the terahertz region. Cloud (Gattini, CSTAR, HRCAM, webcams) Cloud cover statistics and distribution. PLATO science