SkyView: The Internets Virtual Telescope http:skyview'gsfc'nasa'gov

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SkyViewThe Internets Virtual
Telescopehttp//skyview.gsfc.nasa.gov

• Reg White
• Jaime Thompson
• Chris Hurley

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What does SkyView Do?

• Allows users to generate images of any portion of
  the sky at wavelengths in all regimes from radio
  to gamma-rays.
• Intended for celestial objects outside the solar
  system
• Basic purpose is to make available to users
  images of the sky captured at different
  wavelengths

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Domain and Scope

• Site is
• Amateur and Scholarly
• Scientific
• Professional
• Surveys
• Each survey has special properties
• Data is collected from all over the world
• Wavelengths

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Domain and Scope

• Type of System
• SDI (Selective Dissemination of Information)
• Data from all Astronomical Regimes
• Emphasize data from high-energy astrophysics
  satellites
• Open Archives Policy
• Anyone can browse the system
• Part of HEASARC

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Information Items

• Images represented as GIF or FITS (Flexible Image
  Transport System)
• Can also display TIFF
• Users can save any annotations or overlays added
• Many images are false color

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Attributes Fields

• Indexed Fields
• Source Coordinates
• Source Name
• Other Parameters
• Sub-fields or Sub-categories that can only be
  searched on when a specific object has been
  selected

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Search Operators

• No Default Search Operator No Boolean Searching
  Available
• Surveys
• Data collected from orbiting satellite or
  Earth-based telescope observations during a
  specific period of time
• Wavelengths
• Different characteristics of images can be seen
  with different wavelengthsOptical, X-Ray, Radio,
  Gamma-ray, Infrared, EUVE

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Wavelengths Cassiopeia
?Gamma-ray Optical?
?Infrared Radio?
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Access Methods

• In order to see something in SkyView
• Need to know where to look (e.g. an items
  position coordinates or name
• Need to know what wavelength to view the item in
• Interfaces
• Non-Astronomer
• Basic
• Advanced
• Java
• Customized

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Search Interfaces

• Non-Astronomer Interface
• Quick access to SkyView
• Users needs little or no astronomical knowledge
• Only provides false color images
• Basic Interface
• More options but still simple
• User has choice of surveys, area, and image size
• Only provides false color images

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Search Interfaces

• Advanced Interface
• User has even more control over image size and
  resolution
• Allows user to combine data from multiple images
  and to overlay images
• Provides true color images

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Search Interfaces

• Java Interface
• Interactive
• For those with a java compatible browser
• Provides 3-D Images
• Customized Interface
• As much information as the Advanced Interface
• Users can choose and save search options

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Searching

• Required Parameters
• Name or Coordinates
• Wavelength
• Optional Parameters
• Coordinate System
• Projection
• Brightness Scaling
• Image Size
• Grid
• Equinox

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Access Methods

• Only available online
• No password required
• No login ID required
• Available for free to all
• Constraints
• Need a Java-capable browser to view Java
  Interface
• Need a browser that can view images

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Similarity/Relevance Estimation

• Little Query Structure
• Check boxes or choose options
• Not Content-based Retrieval
• Precision and Recall
• Either 1 or 0 (either you retrieve an image or
  you do not)
• Documents are not related
• No relevance feedback

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Search Results
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System Usability

• Excellent help pages
• Non-Astronomer interface very easy to use not
  too technical
• Some Very Technical Interfaces
• Multiple Required and Optional Parameters
• At least ½ billion objects cataloged
• As non-astronomers, cannot really rate the
  usability of the more technical interfaces

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Critical Analysis Strengths

• Large number of images available in various
  wavelengths
• Ease of use, Simple design
• Various search interfaces based on level of
  astronomical expertise
• Excellent help documentation
• Images available to anyone for free
• Encourages user feedback

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Critical Analysis Weaknesses

• No relevance formula either you retrieve an
  image or you do not
• Cannot compare images
• Cannot cluster results
• No available information on specific celestial
  objectshave to go elsewhere to find star
  names/coordinates
• Independent database

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Recommendationsfor System Improvement

• List of, or links to, common star names and
  coordinates
• Add searches for types of objects e.g. black
  holes or nebulae

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Additional Comments

• Searching is very complex due to the scientific
  nature of the data housed here
• Some weaknesses may not be weaknesses, except in
  the mind of a user who prefers specific features
  in any IR system

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Questions?