UDON2 quick user-guide

UDON (Universe via DARTS ON-line) is a system for browsing and quick analysis of the Suzaku data on DARTS using standard Web browsers. The following functions are available for Suzaku XIS data:

  1. Display pseudo-color images, changing color contrasts.
  2. Specify a region on the displayed XIS image, extract the light-curve and spectrum from the region. The extracted light curve and spectrum are displayed on the screen, and also FITS or QDP files can be downloaded.
Please read the help page for details.

Quick Start

  1. Find the data from the public data-list page, click links to UDON.
  2. On the UDON page (example for Eta-Carina), there will be two images (large one in the center and small on the upper-right). These are pseudo-color X-ray images, using energy boundaries displayed on the left. Intensities in the X-ray soft, medium and hard bands correspond to Red, Green and Blue colors, respectively.
  3. In the central image, specify the region using the left button on the mouse.
  4. Use the "Reset" button to specify another region.
  5. Specify the "Submit" button on the right. Now, image and spectrum are being extracted.
  6. The extracted spectrum is displayed in the new Window or Tab of the browser. Click the "Light Curve" button, then the extracted light-curve is displayed.


  • Suzaku has four XISs, and all the XIS event data are combined.
  • HEASOFT (extractor) is used to extract an image, spectrum and light curve. After making these histogram, you may find the log by clicking the upper-left image.
  • [Image] You may change energy boundaries for Soft (Red), Medium (Green) and Hard (Blue) bands in order to change color contrast.
  • [Image] You may magnify or reduce the image. Celestial coordinate of the mouse position is displayed on the image.
  • [Region] You may specify the region in the shapes of Circle, Ellipse or Rectangle. You may either specify the central position or corners of the shapes.
  • [Histogram] You may change the XY regions and scales (linear/log) of the light-curve or spectral plots.
  • [Histogram] You may download the extracted light-curve and energy spectrum in FITS and QDP formats.

Last Modified: 05 June 2018