plato operation and dome a site propertiesaag.bao.ac.cn/academic/xian/ppt/8.18am/ashley.pdf ·...
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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
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
Collaborators
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
Two major problems:
(1) turbulence
(2) absorption
Traditional choices include the west coast of Chile
and Mauna Kea Observatory, Hawaii
Both these sites have relatively smooth airflow and
excellent “seeing”, but can we do better?
+ Dome
F
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
Cumulative seeing
probability
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
Dome
F
So, where is the best site in Antarctica?
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)
Pre-HEAT
Gattini SBC
Gattini all-sky
Iridium antennas webcams
Instrument module
spare
ports
CSTAR, SNODAR, Sonics located
externally on snow surface
The 2009 Chinese traverse
570 tonnes
Dome A traverse 2008
Dome C
Dome A
11 Jan 2008
Polar Research Institute of China tractor traverse 2008:
18 expedition members
2 astronomers: Zhou Xu (NAOC), Zhenxi Zhu (PMO)
Images courtesy Li Yuansheng, PRIC
Zhongshan
23 Dec 2007
PLATO on its two week trip to Dome A, December 2007
PLATO at Dome A, January 2010
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 2008. •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.
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 (low-
resolution (2.5nm) 300-900nm); 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
CSTAR: four co-mounted Schmidt telescopes
- 145mm aperture, f/1.2
- 4.5 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 2009
- three papers published in 2010
Pre-HEAT 20cm off-axis parabola
661GHz (450 micron) Schottky diode heterodyne
receiver
Measures sub-mm sky transparency, and hence PWV
(Precipitable Water Vapour)
Gattini wide-field multi-filter
optical camera
PI: Anna Moore, Caltech
> 1.2TB of images have been
obtained in 2009/2010.
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.
Nigel’s “bob”
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.
Gattini-Nigel: a bright aurora
SNODAR
Snodar data; each plot 24 hours;
0-120metres
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
respectively.
Cumulative histogram of the boundary layer height
Dome A comparison with Dome C
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)
Webca
ms Moonrise at Dome A April 2008
HRCAM all-sky image, showing
the traverse leaving Dome A,
January 2010
HRCAM images 2010
HRCAM images taken last night, showing the coronal mass
ejection of 2 August 2010 reaching the earth
Where the power came from
Where the power went
Fuel consumption
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 (low-
resolution (2.5nm) 300-900nm); 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