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Key elements of MAST interfaces are summarized here, and include Portal = tutorials for users new to MAST.
On this page...
Certain operations require that you log into MAST. This includes access = to most data from active JWST observing programs. See MAST Ac= counts for details.
If you have a MyST account and login to MAST you may subscribe to notifications about JWST program data= availability, even for observations that have not yet executed.
All data from JWST will eventually become public, and anyone may conduct= searches for JWST data. However, when data fall under an exclu= sive access period (EAP) the files may only = be retrieved by authorized persons. To retrieve EAP data from MAST:
MAST offers a multiple web-based tools to search for and retrieve scienc= e and engineering data, or for other information. Links to these tools appe= ar in the table below.
Search Type | Select a collection... | URL |
---|---|---|
Observation= s of a target or field | MAST Observation= s by Object Name or RA/Dec | https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html |
Observation= s Matching a Program ID | Observations by Prog= ram ID | |
Files match= ing Instrument Keyword Values | JWST Instrument = Keywords | |
Wavefront S= ensing products | JWST WSS | |
DOI Portal<= br> | https:= //mast.stsci.edu/portal/Mashup/Clients/DOI/DOIPortal.html | |
Calibrated Engineering = Data | http= s://mast.stsci.edu/portal/Mashup/Clients/jwstedb/jwstedb.html | |
Keyword Dictionary | htt= ps://mast.stsci.edu/portal/Mashup/Clients/jwkeywords/index.html |
Browser Issues
=Note that the MAST Portal has incompatibilities with certain browsers an= d settings. In particular, pop-up blockers must grant an exception for the = = mast.stsci.edu domain. For details see Intro= duction to the MAST Portal in the Portal Guide.
Many users find scripted access to MAST sea= rches and data retrievals to suit their needs better. The most popular inte= rface offered is the Python package as= troquery.mast. A brief tutorial is appears near the end of this article= , and more extensive documentation is offered in the JW= ST Archive Manual in the Using MAST APIs chapter.= p>
The MAST Portal search panel is shown below. It is a starting point for = your interactions with MAST.
All of the searches described below start with selecting the appropriate= collection for a search, from the drop-down menu shown at = right.
Search results are displayed below the search panel, as shown in the exa= mple below.
Results consist of Filter dialogs (left); a table of matched re= sults (center) showing rows for public (white background)= , Exclusive Access (yellow background, with the padlock icon), and= planned but not yet executed observations (orange background); an= d the AstroView tool (right) which shows the spatial extent (c= olored footprints) of the exposures superimposed on an image of the sk= y. For details see Field Guide to the Portal.=
Many types of Portal search return Observations, which are really collections of all available data products, including u= ncalibrated, intermediate, fully calibrated, and combined science data. See= Linkages in the Porta= l to learn more about how various kinds of data products are associated= in the Portal. See Download Basket= a> to learn how to select and download one or more of these types of produc= ts.
A basic search will return Observations from all hosted MAST missions. <= strong>This search will provide access to all levels of JWST data products.=
An advanced search allows you to customize = the query by additional attributes, and can return Observations for all hos= ted MAST missions. This search will provide access for access to all levels= of JWST data products (unless you choose to restrict the calibration level= ).
This type of search will return all Observations for a given observing p= rogram (a.k.a. proposal number). This is a quick way for Investigator Teams= to search for all data related to their science program.
This search will match program IDs for both JWST and HST, even though th= e results for one mission are not scientifically related to the other. It i= s easy to filter the results table for the mission of interest.
This type of search for JWST data provides a much larger set of criteria= , including important metadata that are not available in standard searches = such as:
tsovisit
)exp_type
, which could indicate, e.g., coron=
ographic observations)observtn
)category
, e.g., COM and ERS where all da=
ta are instantly public)Beware that this type of search matches data for only one selected JWST = instrument, and only the highest-level calibrated science FITS files.
Highest-level products only!
This kind of search will not provide access to ancillar= y files, nor to uncalibrated (e.g., Level-1b) files if higher-level product= s exist. It will also not match calibrated files that are not in FITS forma= t, such as source catalogs or light curves.
There is a way, using scripted queries, to search by values of instrumen= t keywords and return Observations, that is, complete collections of all da= ta products that match the query criteria. See API Tutorials for details.
There are multiple options for downloading data products from MAST. Each= option has its strengths, as noted below.
Searches that return Observations to the results table contain links to = all available JWST products associated with each Observation. Place one or = more results in the Download Basket to view and select exactly which produc= ts (e.g., uncalibrated data) to download.
This is the simplest form of download, and works for individual entries = in the results table. The download bundle is streamed to your machine throu= gh your browser.
MRP files only
=This form of download is intended for retrieving multiple observations a= t once, and for retrieving all (or only selected) types of products. There = are three options: immediate streaming download (which imposes a size limit= ), and retrieval by curl script or ftp staging (which do not).
This example applies to results that contain Observations, rather than i= ndividual files (as you would have after an Instrument Keyword search).
This type of retrieval is asynchronous and has no limits to the volume o= f data to download. It is more robust against internet interruptions, and c= an be resumed if interrupted.
Staging files for ftps retrieval is currently supported= for a few MAST missions (including JWST and HST), but not all. It is highl= y recommended to instead retrieve large numbers of files via cURL scripts.<= /p>
The following tutorial introduces the basics of MAST queries with the astroquery.mast package. More extens= ive documentation is offered in the JWST Archive Manual= in the Using MAST APIs chapter.
All data products for all selected observations will be bundled together= for delivery. When the Zip or tar file is unpacked, data for each observat= ion/visit/exposure will appear in a separate sub-directory.
For each sub-directory, the data bundle includes by default the highest-= level data products, plus all parent data. For example, if an obse= rvation/visit/exposure combination resulted in Level-2 data products, all L= evel-1 products would automatically be included unless the user explicitly = chooses otherwise.
The zip (or tar) file will include a file called MANIFEST.=
HTML
which lists each file name, a short description, and w=
hether access is restricted. It will also note any files that could not be =
downloaded and the reason why (e.g., if you do not have permission to retri=
eve them).
The semantic content of science files may be inferred from the file suff=
ix, and the filename signature. For example, files ending in