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Searching Tips

When formulating a search, note the following:

  • Leading zeros are ignored in the name. For example, M5 returns results for object Messier 005.
  • Object names are not case-sensitive, and spaces between the characters (e.g. M51 and M 51) are ignored unless the space indicates a real character in the name.
  • If an object name is incomplete the name resolvers from NED and SIMBAD return the closest match. This can lead to surprising results however.
  • All coordinates are interpreted as J2000.
  • You can specify the search radius with an "r=<value>" syntax, with units of m, s, d for arcmin, arcsec, deg, respectively.
    • Example using a target name, specifying a 1 arcmin radius: m57 r=1m
    • The maximum search radius is limited on a collection-by-collection basis.
  • VO resources may have arbitrary limits on the number of rows returned, on a resource-by-resource basis.
  • Queries are limited to a single object or position. However, multiple queries may be submitted sequentially, even if one or more queries are still executing.
  • You can save a persistent link (and, e.g., email it to a collaborator) to the results of a search by clicking the link icon:

Tabs of search results are not saved between sessions; once the application has been abandoned, returning to it will not bring up previously searched objects. This means that clicking the browser back button or the refresh button will cause the session to be lost.

Downloading Tips

When downloading data, note the following:

  • If you are working in the Download Manager, your browser must be configured to allow pop-ups from the domain mast.stsci.edu
  • You must be logged in to download data that falls under Exclusive Access Period (EAP); you must also be authorized to retrieve EAP data from a given program.
  • Large files may take a while to download. Download progress can only be monitored using browser tools.
    • Very large bundles may take some time to be created, so you may need to allow up to minutes for the "save file" dialog to appear.
  • Downloading is disabled for data products that are embargoed by the provider. It may not be obvious when this happens except in the MANIFEST.html file, and that no embargoed file will be downloaded to your computer.
  • If you are logged in, the Portal will retain a download history (by date) so that you can revisit prior searches.

Known Issues


  • The Portal web application works reasonably well with recent versions of Chrome, Firefox, and Safari. There are known incompatibilities with MS Internet Explorer and Edge.
  • In Firefox, the scrollbars may not be displayed by default in OSX. In OSX, the default setting for showing scrollbars is set to 'Automatically based on trackpad or mouse'. If you are using a mouse, the scrollbars should be visible. However, if you are using a trackpad or other touch-enabled device it will attempt to hide them entirely. This can lead to confusion about when a grid or other widget is scrollable or not.

Other Issues

  • The contents of the Download Basket are not persisted across sessions, nor is any customization of the grids.
  • The search box in the filter container accepts regular expressions in JavaScript format.
  • Circular footprints (e.g., GALEX) are currently defined as polygons with a finite number of vertices. When zoomed in close in Astroview, you can sometimes see the footprint line segments, rather than a curved trace of the true circular footprint. As such, targets that are very, very close to the edge of the footprint will appear to lie "outside" the footprint when they are actually within it.
  • For GALEX, the FUV and NUV observations are typically downloaded as a pair, rather than separately.
  • Note: For GALEX, background images used in AstroView are from data release 4/5, but the data available from MAST are from release 6/7. This may cause footprints to be placed in the viewer over objects that are not visible in the viewer.

For Further Reading...

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Send comments & corrections on this MAST document to: archive@stsci.edu