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Mars Image Showing the High Resolution Camera’s “Occulting Mask”

Mars Image Showing the High Resolution Camera's "Occulting Mask"
The Advanced Camera for Surveys on Hubble Space Telescope includes two cameras, the Wide Field Channel (WFC) and the High Resolution Channel (HRC). Images from the WFC are roughly 4,000 pixels square with a scale of roughly 0.05 arcseconds per pixel. Images from the HRC are smaller in pixel size, 1,000 pixels square, but have a finer resolution, 0.025 arcseconds per pixel. The HRC is preferred for images of planets, or objects appearing smaller on the sky, where higher resolution outweighs larger field of view. The HRC also has two occulting masks that can block starlight from bright sources, and allow fainter objects nearby that are otherwise lost in the glare of the brighter object to be visible. One of the masks can be removed, but the other mask, seen in this Mars image at the lower left corner, can not be moved out of the light path. This "occulting finger" blocked a small portion of the light from Mars. The small amount of missing data in the final color composite of Mars was corrected by filling with nearby sections of the image of similar color and texture. This is a method commonly used in digital photography to remove blemishes, but is not used with data published in scientific papers.

About the Object

  • Distance
    DistanceThe physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.
    The semi-major axis of Mars' orbit about the sun is 1.52 Astronomical Units (A.U.) or 142 million miles (228 million km).

About the Data

  • Data Description
    Data DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
    Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.
    This image was created from HST proposal 10770: K. Noll (The Hubble Heritage Team, STScI), J. Bell (Cornell Univ.), M. Wolff (Space Science Inst.), H. Bond, C. Christian, L. Frattare, F. Hamilton, W. Januszewski, Z. Levay, M. Mutchler, and T. Royle (The Hubble Heritage Team, STScI).
  • Instrument
    InstrumentThe science instrument used to produce the data.
    HST>ACS/HRC
  • Exposure Dates
    Exposure DatesThe date(s) that the telescope made its observations and the total exposure time.
    October 28, 2005
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    Mars
  • Object Description
    Object DescriptionThe type of astronomical object.
    Planet
  • Release Date
    November 3, 2005
  • Science Release
    Mars Kicks Up the Dust as it Makes Closest Approach to Earth
  • Credit
    NASA, ESA, and Z. Levay (STScI)

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Details

Last Updated
Mar 28, 2025
Contact
Media

Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov