Authorized users may access and retrieve selected telemetry and supplemental JWST data product types using the CaSSI web interface, or with curl commands.
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Product Search
The MAST CaSSI web interface includes a search form for a subset of restricted JWST data products, including raw science and engineering telemetry downlinked from the spacecraft. The web search interface is shown in Fig. 1. The various search parameters are described in the following subsections.
Searches for the CaSSI products described here are restricted to authorized persons. This means you must have an account in MyST, and be logged in to a MAST session to search for or access these data via the Web interface. If you are using an API, such as astroquery, you must pass a valid MAST token in the call to the applicable service. See the MAST API Tokens article for details.
If you believe you should be authorized to search these restricted products but cannot, contact Archive User Support to request authorization.
Figure 1. CaSSI interface (above), and the Data Group selector within it (below) to search for JWST supplemental and telemetry files. The message Filtered results: at the bottom of the window dynamically updates the count of all files that match as values are entered for the search parameters.
Date of relevance
Use the Date dialog box to select files that pertain to a date of interest. The date that applies to these products is currently derived from date substring embedded in the file name. Note that the contents within the files may span a date boundary.
Click the date picker icon (
) and choose a year/day/month from the calendar, as shown at left, or simply type the date into the dialog box, in YYYY-MM-DD format.
Since not all file types include an embedded date string, choosing a date will implicitly exclude these file types from your search.
Product File Type
You may constrain a product search to one or more of the supported file types, which are listed in the table below. The default (i.e., no types selected) is to match any file type. File prefix characters are given when they apply to all files of a given type.
| Prod. ID | Product | File Prefix | File Suffix | Description |
|---|---|---|---|---|
| 1 | Recorded Science Data | S0000 | .out | Raw telemetry from the SSR science partition. Data from instruments operating in parallel are interleaved. (Binary) |
| 2 | Recorded Engineering Data |
| .out | Engineering telemetry from the SSR engineering partition. Data are in engineering units, collected from tens of thousands of telemetry points on the spacecraft and within the instruments. (Binary) |
| 3 | Observatory Status File | _osf.xml | Summary of instrument and spacecraft activities, in time order (XML) | |
| 4 | Observatory Ephemeris* | JWST_ | .OEM | Either predicted or derived spacecraft position (km) and velocity (km/s) in X, Y, Z as a function of time (CSV) |
| 15 | Processing Logs** | .log | Processing logs for the DMS Pipelines (ASCII) | |
| 100 | Diagnostics** | .bin | Currently, diagnostics related to the MIRI grating wheel |
*The coordinate system for the ephemeris data is EME2000. EME is an Earth-centered, J2000 inertial frame, which is a non-rotating equatorial frame with the z-axis aligned with the north celestial pole. Ephemeris files are in CSV format, and include header information.
**Product filenames do not contain date-time sub-string.
Filename pattern
Enter the name(s) for one or more files in the Filename dialog box to match files of interest. A list of filenames can be entered on separate rows in the dialog box. If you wish to select a range of similar names, you can create a filename pattern using a limited set of special characters to match or exclude sub-strings within a filename. The special characters are given below, and are interpreted syntactically within the context of a limited form of regular expressions (re).
| Syntax | Meaning |
|---|---|
| % | Matches any substring |
* | Matches any substring |
[aeiou] | Matches any character in the listed set |
| Matches any character not in the listed set |
[a-z0-9] | The set of characters can include a range or multiple ranges |
The article Regular Expressions, which describes filename matching in the Mission MAST Download Overlay, includes detailed examples of how to use the re syntax. But be aware of important differences:
- there is no implied wildcard at the beginning or end of a filename pattern (though you can add them explicitly)
- more than one wildcard character may appear in the pattern
- the following symbols are interpreted literally
!does not mean logical negation- $ does not denote the end of the string
\(backslash) is not a means to escape special characters
Filename matching is not case sensitive.
File list upload
File names or name patterns can be stored in a file and uploaded to the Filename dialog box by clicking the UPLOAD FILE NAME LIST button. The results of the upload is shown in Fig. 2, below. Note that the patterns must be given one per line in the uploaded file.
Figure 2. Filename matching dialog box, after uploading a list of filename patterns from a local file.
Retrieve Data
A successful search will result in a table of results, one file per row, as shown in Fig. 3 below.
Figure 3. Results window for the search for supplemental engineering. After selecting one or more results (rows with checked boxes and light-blue background), the file(s) may be downloaded via a method selected from the Download Data menu.
Only the first 5000 matching results will be accessible in the results window. If the number of potential matches equals or exceeds this limit you will need to click the EDIT SEARCH button and narrow your search criteria.
Various elements of the results table are described in the article Search Results Page, including:
- revising the parameters of the search and re-executing
- exporting the results table to a file
- selecting table rows
- navigating to pages in the results table
Choose the files of interest for download, then click the Download Data button to select the retrieval method.
Large Downloads
If the combined size of the selected data files is large (>1 GB), we recommend downloading the retrieval script and running it on your machine to minimize the chance of server-side timeouts or other transfer problems.
Product download API
In addition to downloading the files via the browser window, you may choose to download a retrieval script.
Selecting the API Script/Curl option will bring up a set of curl commands (one per file), which you can copy to your screen buffer, or download to your machine as a bash script. Run the script with a command similar to the following:
bash MAST_2025-03-24T191812_retrieve.sh