Context

Any search with the MAST Portal requires first specifying the collection over which to search. Select the collection with the drop-down menu at the top-left of the Portal interface:

MAST Portal collection pull-down menu

See the Selecting Collections section of the Basic Search chapter in the Portal Guide for an explanation of the various collections.

Search by Object Name or Coordinates

The most common search in MAST is to specify either an object name, or a location on the sky in equatorial coordinates. See the Basic Search chapter in the Portal Guide to view the accepted formats for target names and for coordinate syntax. In brief, after selecting the collection:

1. Enter a target name or coordinates into the dialog: MAST Portal target/position dialog box
2. Click the Search button:

Note that you may want to specify a search radius in the dialog (e.g. "ngc2024 r=1m") if the default of 0.2° returns too many results.

Advanced Search

An advanced search is really an elaboration on the basic search by name or position, but provides 30 additional attributes for a finer-grained selection. In brief, after selecting the collection

1. Click the Advanced Search link, which brings up a new window (see the Advanced Search article in the Portal Guide)
2. Select the filter columns of interest
3. Fill in the dialog boxes (or select enumerated values) in each filter of interest
4. Execute the search

An advanced search is a good choice if, e.g., you want to find data for a particular JWST program: select JWST in the Mission filter, and enter the 5-character program number in the Proposal ID filter.

Search Results

After a successful search the Portal returns a table of matches to Observations. Each match appears as a row in a table, and each row represents multiple data products. See the layout in Figure 1 of the Field Guide to the Portal chapter of the Portal Guide.

Search by JWST Instrument Keywords

The JWST Instrument Keyword search will select files that match header keyword values (or ranges of values). See the JWST Keyword Dictionary for a complete list of the scores of available keywords for each instrument.

A brief description about the JWST data product levels can be found in the Science Data Products article; see also the JWST processing pipeline page for more detailed information.

Example Search by Keywords

Follow the instructions below to search by specific keyword values. This example shows how to search for NIRCam observations in the F212N F070W filter for JWST Program 7101063, and then refine the results to display only those files from Observation 72100.

	Instruction	Notes
1	Select 'JWST Instrument Keywords' from the Select a collection… drop-down menu on the upper-left of the Portal interface.	Image ModifiedMAST Portal collection pull-down menu
2	Select an instrument (in this example, Nircam) from the Instrument pull-down menu underneath the collection drop-down menu.	Center Image ModifiedMAST Portal instrument pull-down menu for JWST keyword search
3	Click the Advanced Search button on the right, which will bring up a new window.	Center Image ModifiedAdvanced search button
4	Select parameters or ranges for one or more filter menus to limit or expand the search. For instance, specify the JWST Program ID in the Proposal ID panel and tick the filter name (in this example,

F212N

F070W) in the Filter panel.

Tip
Be sure to add leading zeros to the Program ID value (e.g., 00710) to make a 5-character string.

Image AddedFiltering by proposal ID Image AddedLimiting results based on filters used

Image RemovedPortal advanced search filter for proposal ID

Image RemovedPortal advanced search filter for instrument optical element

5	Now click the Search button in the upper-left of the Advanced Search window.	Image Modified
6	Evaluate the search results grid (i.e., the table of matching rows).

Image RemovedPortal search results table

Image AddedSearch results grid
7	Optional: Click an information icon Image Modified in a table row for additional details about that file.

Image RemovedPortal Observation details

Image AddedFile metadata information
8	Optional: Down-select results in the grid using one or more of the Filters to the left of the results table. When specific filters (e.g.,

observtion 72

Observation 100) are applied, the results table will display observations that match those selections.

Image RemovedPortal results window filters panel

Image AddedOptions for filtering the results table
9	Optional: Click the Edit Columns button at the upper-left of the results table (see

instruction

Step 6 above) to

pop up

open a menu, where you can select which columns are displayed in the results table. The default is to display columns for all keywords, which requires a lot of sideways scrolling to find those of interest.

Image ModifiedEdit columns button

Search for Wavefront Products

JWST's primary mirror (the Optical Telescope Element, OTE) has eighteen individual segments. To enable the segments to act like one large primary mirror and to have their wavefronts match correctly, the initial best on-orbit alignment is established during JWST commissioning, and periodically thereafter. Wavefront sensing results include Optical Path Difference (OPD) files, which are available in the MAST Portal. It is possible to use these files with mission software (Webb PSF) to evaluate the quality of the imaging for an instrument and aperture of interest.

Bring up the Portal interface and follow the steps below:

	Instruction	Notes
1	Select 'JWST WSS' from the 'Select a collection…’ pull-down menu on the upper-left. Tip WSS refers to the Wavefront Sensing Software subsystem for JWST.	Image ModifiedMAST Portal collection pull-down menu
2	Click the Advanced Search box to the right.	Image ModifiedAdvanced search button
3	Select parameter values for one or more filter menus to restrict the search. Note: wildcards are allowed in text boxes.

Image Removed

Image Added
4	Click the Search button in the upper-left of the window.	Image ModifiedSearch button
5	Optional: Down-select results in the grid using one or more of the Filters to the left of the results table, which when applied will display only the matching observations.

Image Removed

Image Added
6	Download the products by: selecting a single entry in the results table, then clicking the file icon, or placing in portal basket, then download See Data Retrieval article for more details about downloading data.	Center Image Modifiedor

 

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For Further Reading...

• MAST Data Holdings
• MAST Portal Guide