Observations of Zodiacal Dust

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?????Observations of Zodiacal Dust

• Munetaka UENO (U Tokyo)
• Masateru ISHIGURO (UH), Fumihiko USUI
  (ISAS/JAXA),
• Suk-Minn KWON (Kwanwon U), Tadashi MUKAI (Kobe U)
• Kazuhiro SEKIGUCHI, Akihiko MIYASHITA, Masao
  NAKAGIRI
• Takafumi OOTSUBO (NAOJ) and WIZARD Team

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Introduction--- What is zodiacal light? ---

• Scattered light by interplanetary dust
• Zodiacal light
• Leading / Trailing side
• The gegenschein
• a faint spot of light in the sky, diametrically
  opposite Sun (backscattering)
• Interplanetary dust cannot stay long under
  Poynting-Robertson Drag
• It requires continuous supplies of the
  interplanetary dust
• Very basic studies for future observations
• Recent possibility to observe zodiacal light of
  extra-solar planetary system
• To know Star Planets Dust clouds -- system

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Introduction--- Zodiacal light observations
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• Zodiacal light is VERY extended and very FAINT
• Hard to observe precisely
• Influences of atmospheric scattered light,
  airglow, star light and etc. make data reduction
  very hard and comprehensive
• Waiting for the NEW instrument which gives us a
  break-through of ZL observations
• ---gt WIZARD

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Development of WIZARD--- What's new? ---
 

• Large FOV and good spatial resolution
• To cover the ZL and dark sky simultaneously
• High spatial resolution to remove the star light
• Very high sensitivity
• Excellent image quality
• Stability of DC level (zero level)
• Airglow suppression filter

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WIZARD overview
camera
optics
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WIZARD overview 2
control
mounting
misc.
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WIZARD
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WIZARD Optics
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Airglow suppression filter
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Control system
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Observations at MaunaKea

• Date
• Feb. 18-26, 2001 (RD and Final check)
• Mar. 19-28, 2001 (First light and test
  observations)
• Mar. 8-18, 2002 (Observations)
• Feb. 28 - Mar. 3, 2003 (Observations)
• Aug. 21-28, 2003 (Observations)
• Oct. 25-28, 2003 (Bad weather)
• Site
• SUBARU site (near the large entrance) - Mar. 2003
• Backyard of IRTF Aug. 2003 -

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Milky way
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Observation coverage
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Data reduction
Raw data
Dark, flat operation Vignetting, Point source
reject
Integrated flux of stars by Pioneer 10/11
Uncalibrated Data
Photometric calibrations using the point
sources Extinction for extended source
Zodiacal Light flux
Airglow subtraction
Calibrated data
Star light subtraction
Zodiacal light subtraction Using 3D zodiacal
light model
iteration
Airglow flux
Airglow
Fitting operation of night light and
atmospheric scattered light using Van Rhjin model
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Brightness Distributionalong the ecliptic
longitude
Below the horizon
Galactic plane
Anti-solar point
Intensity (S10)
l- lsun ()
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Kelsall model (i2.03, O77.7) Hongs
scattering function
i4.0, O77.7 modified scattering function
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Scattering phase function derived by our
data with numerical model (Hong 1985)
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Summary

• Coherent back-scattering of the dust surface must
  be a dominant mechanism for the bright spot of
  the gegenschein (suggesting large and fractal
  dust is leading the opposition effect)
• Symmetric plane of the zodiacal dust cloud is
  different from 3D model derived by COBE data
  (suggesting distribution of smaller dusts are
  different from the large one)
• Lots of fine structure (Dust bands of asteroids)
  in zodiacal light are detected