Digital Sky Virtual Observatory Prototype


Apply High Performance Computing and Communications technology to visualize and analyze the Digital Sky datasets, both imagery and catalog data from DPOSS, 2MASS, etc., at arbitrary resolutions. The end product will be a "virtual observatory" enabling viewing of tens of terabytes of image and catalog data and having functionality illustrated in Figure 1.


Figure 1. Digital Sky Virtual Observatory overall vision


The SGI Visualization and Data Center at JPL is being used as "home base" for this virtual observatory prototype. Most of the functionality is also accessible at the user's desktop with reduced performance.  We are leveraging SGI Electronic Light Table technology and the Image Vision Library to build the main interactive image and catalog viewing application.    Additional technology being developed in conjunction with this task includes large-scale image mosaicking and registration for viewing of multi-spectral data from multiple sources, and large data management tools to download requested data from the Digital Sky archives and discard or offload to a tertiary store the data that is no longer required.


  1. Developed image mosaicking software that can be used to create mosaics of arbitrary size and resolution by reprojecting FITS (the standard image format adopted by the astronomical community)  images into a common projection.  Used this new software to construct the first full resolution all-sky IRAS mosaic from 430 individual patches with 4 bands each and the first cross-survey 2MASS/DPOSS 6 band mosaic covering about 10 x 10 degrees for 2MASS and 2 x 2 degrees for DPOSS.
  1. Expanded the SGI Electronic Light Table into a "virtual observatory" by adding the following features:


    • Multi-screen powerwall display supporting any number of screens and any resolution supported by the hardware,
    • Ability to relate pixel coordinates to sky locations and vice versa,
    • Catalog data viewing in ASCII text format in a scrollable window,
    • Large image navigation improvements including:
      • smooth pan and zoom
      • astronomical coordinate entry,
      • jump to location by clicking in a synoptic map view,
      • jump to location of a celestial object by clicking on the object's catalog entry,
    • Image processing capabilities (e.g. brightness and contrast adjustment),
    • Interactive selection of any 3 bands in a multi-spectral image to be mapped to the red, green, and blue video channels,
    • Support for overlays to draw annotation symbols on top of selected celestial objects,
    • Relation of a location in the image data to catalog entries in the proximity and vice versa.


A slide showing screen captures illustrating the catalog/image search functionality of the Virtual Observatory


It has only been in the last few years that we have entered the era of nearly unlimited scientific information; multi-terabyte databases are suddenly not uncommon.  However, sheer volumes of scientific data, no matter how expensively obtained, are of little value without an effective ability to analyze them quickly and thoroughly, and to distill the essence of scientific knowledge from them.  The technology exemplified by this Virtual Observatory prototype is essential for data management, analysis and visualization of the multiple terabytes of image and catalog data in the Digital Sky surveys.


Future work to be done on this task in the next fiscal year includes the following:  (i) creation of synthetic images from th DPOSS and 2MASS catalog data, (ii) development of large data management tools that will permit users or system administrators of the Virtual Observatory to easily control what subset of the Digital Sky data is mirrored on local disks or on a tertiary store, (iii) creation of larger DPOSS and 2MASS mosaics.

Points of Contact

David W. Curkendall

Joseph C. Jacob

Jet Propulsion Laboratory

Jet Propulsion Laboratory

(818) 354-2406

(818) 354-0673