HST Data Handbook for WFPC2

1.3 Getting Data With the World Wide Web

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HDA datasets can be searched for, previewed and retrieved via the World Wide Web in very much the same way as with StarView. As noted in section 1.1, StarView offers more capabilities for this process, including cross-qualification, the use of VTT, and more information about instrument calibration files. However, Web retrievals may be preferable in some cases, particularly when information on calibration files is not needed, and the hypertext on the Results pages makes it easy to access all the information they contain. The starting point for Web-based searches of the HDA is the MAST web site at: http://archive.stsci.edu¹

This web page is shown in figure 1.6. A powerful feature of MAST is that all of its mission archives, including the HDA, can be searched simultaneously. This is done with the Cross-Correlation Target Search option shown on the MAST home page. This search will return all datasets for all missions available for a given object or coordinates, according to the search constraints specified by the user (based on the wavelength region of interest), and will provide hypertext links to these datasets. If only HST datasets are desired, they can be accessed separately by clicking "HST" on the MAST home page.

The HST section of MAST offers tutorials about the HDA as well as a FAQ page and HDA news. It also provides links to HST Prepared datasets such as the Hubble Deep Field images. Clicking on the "Main Search Form" option of the HST section brings up the page shown in figure 1.7. Here the user is queried for the same search parameters as requested by StarView, e.g., Object Name, Instrument and Proposal I.D. Once these are entered, clicking the Search button returns a page listing the datasets found, which can then be selectively marked for retrieval. The data type and retrieval options remain the same as those for StarView. Previews of GIF files of the datasets are also available.

¹ European archive users should generally use the ST-ECF Archive at http://archive.eso.org. Canadian users should request public archival data through the CADC web site at http://cadcwww.dao.nrc.ca. Proprietary data are only available through STScI.