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Most astronomical archives present a static, resolution-reduced image of a data product as the only way of judging data quality via visual inspection.  While this is sufficient for basic pruning of datasets, you are still required to download the actual dataset to fully vet its value for a science goal. The PPA Image Explorer allows you to visually analyze your data in real time from within any common Web browser capable of rendering the HTML5 canvas, without having to download several GB of data. The basic features of Image Explorer are modeled on the commonly used desktop application SAOImage ds9 including:

  • Pan, zoom in/out
  • Change the contrast
  • Adjust the intensity scaling
  • Add color maps


Image Explorer goes beyond the basic visual inspection of pre-generated tiled PNG images by letting you execute integrated tools on the PNG or the underlying FITS image. These tools include:

  • Cutout: A box appears to drag-select the region you desire. Cutout button on bottom right will pop up a Process window (Process: Task spawned off ) and report status of cutting out.  Once complete, click on link to download the FITS file to your local disk.
  • Crosscut:  A line appears to drag-select start/end point for the cut on the image. Once these are chosen, a pop-up window with selected line-cut. Displays normalized intensities. Right-Click on mouse on the graph will produce a .png file for saving locally.
  • Image Statistics (imstat): Selecting Imstat will show a Toolbox Icon. Click to select parameters. Click Submit. A Process window appears. Once the Job is complete, click on the link to display the image statistics.

Source Catalog Overlay

Image Explorer includes a complementary Source Explorer tool that lets you overlay source catalog information over your astronomy image. You can generate the sources using SourceExtractor (executed on the underlying FITS image using nodes on IU supercomputers), or query an existing commonly used source catalog for information based on your image's RA/DEC, or you can upload your own source catalog information.