After a successful search for data, and browsing to determine which observations are of interest, the next step is to select particular data products for download. Since JWST provides so many files per observation, it is especially important to choose carefully the products that are most relevant for your science goals.

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File Selector

The Portal Download Manager window provides mechanisms to select which files will be packaged for download. Careful file selection is especially important for JWST Observations because so many science and supplemental files (often hundreds, or even thousands) may be related to one another. Use the file browser tree in the File panel to select files, or directories of files, as show in the Figure below. See the Download Basket article in the Portal Guide for details.

The file navigation panel in the Portal Download Manager window. Check boxes in the Filters panel (left) to select which product types, categories, file extensions, etc. to display in the Files panel (right). Select individual files or directories of files in the Files panel by checking the adjacent boxes.


It is common with JWST queries to find very large numbers of files that are related to even a single Observation. The Filters panel provides a way to hide many categories of files that may not be of scientific interest, such as auxiliary products (which include guide star data), preview images, and the like (see Supplemental Products for details of non-science data products). Filtering makes the process of excluding unwanted files vastly more efficient.

Use Care When Filtering

The default setting for the Recommended Products filter is that only Minimum Recommended Products (usually Level-3) are displayed. This has the effect of hiding all lower-level products, including the contributing L-2b (fully calibrated per detector) files which may be useful for scientific analysis. See Science Data Products to learn more about JWST product levels. It also has the effect of suppressing the ability to select static calibration reference files (see below).

Removing Files from the Basket

If the number of files is so large as to make file selection confusing, you may elect to first filter for files of no interest (for example, guide-star products), select them, and remove them entirely from the download basket by clicking the Remove Selected button in the upper left of the window. Then resume filtering for files of interest.

Calibration Reference Files

Click the Retrieve References button to retrieve the static calibration reference files that were used to create your selected science products. This action will bring up a file selector sub-menu to select files to add to your basket. For the step-by-step guide for reference product retrieval, see the MAST Portal Guide chapter on retrieving Calibration Reference Files.

You must uncheck the MRP filter check box and select at least one calibrated product for the Retrieve References to be active. Note that after you add reference files to the Basket (in the sub-panel), you must then select them in the Download Manager to be included in the download bundle.

Data Retrieval

After selecting all files of interest, they may be downloaded via one of the available methods. Click either the Download button or the Batch Retrieval button; see the Data Retrieval article, or the Retrieving Data chapter of the Portal Guide.

For Further Reading...

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