JWST Data Exploration
Investigators have a variety of tools at their disposal for exploring JWST data, and data from other missions and surveys with the MAST Discovery Portal, and also with community-based tools. Web- or desktop-based tools enable Archive users to plan JWST observing programs, and to place JWST observations in the context of all archived astronomical data. Investigators may also explore JWST engineering data to more fully understand how spacecraft operations may affect their science data.
Tools for data exploration
While the point of an initial search with target- or observation-specific criteria is to discover observations of potential interest, the goal of data exploration is to evaluate the applicability of observations to your science goals. After performing a search for data, there are a number of tools available in the MAST Portal to help sort, visualize, and refine the results. These tools enable users to explore JWST data, view images and footprints from other hosted missions and surveys, cross-match and plot source catalogs, and view time series of selected targets. These capabilities facilitate planning JWST observing programs, exploring JWST data once the observations are available in the Archive, and understanding existing JWST data in the context of the world wide collection of data on a given source or field. Below are descriptions or links to tutorials on how to use these tools.
Native MAST tools
Exploring data begins with a successful search for JWST or other data that meet your scientific criteria. Figure 1 shows the results of a simple query of a target name in the Portal.
The Portal window
See the article Field Guide to the Portal in the MAST Portal Guide for a tour of the anatomy of the Portal interface. Three main panels and a toolbar provide tools for selecting and visualizing the search results. These features are described in detail in the Portal Guide chapter Browsing Data, and are summarized briefly below. Following exploration and visualization, the next step will be selecting data for download, as discussed in the Data Retrieval section.
Left panel: refine the search
The leftmost panel of the results page provides a number of filters to isolate specific data characteristics of interest. These include product types (image, spectrum, time series, etc.), mission (HST, SWIFT, FUSE, etc.), instrument, optical elements, etc. See the Refining Results with Filters article in the Portal Guide for details.
Middle panel: select and preview results
The results of a search, as modified by filters, are presented in tabular form in the center panel, one result per row. See the article Search Results Grid in the Portal Guide for details. Just above the table is a toolbar that provides options for viewing and manipulating metadata, and for bulk selections of results. The table itself provides tools for choosing which fields in the results to display (i.e., metadata like the mission, instrument, target name, and so on), tools to visualize data (i.e., viewers for spectra or time-series) and an option to overlay an image in the AstroView tool. Each row also includes a selection checkbox for placing results into the Download Basket for retrieval.
Among the options for data visualization in the results table is the Jdaviz tool, which was built for JWST data. You can use it to browse JWST spectra (MOS, IFU, fixed slit, etc.). See the article JWST Data Analysis Visualization Tool for details. This tool may be used stand-alone on your desktop, in Jupyter Notebooks, or (for MAST) in a web application. The Jda tool icon will appear in the Actions menu of the MAST Portal results table.
Right panel: visualize exposure footprints
The right side of the Portal search results displays the AstroView panel, which displays a sky-survey background of the target area, overlaid with wireframe spatial footprints of the matched observations. See the AstroView article in the Portal Guide to learn how to customize this tool, and to use color to highlight observations with different instruments or observatories.
Catalog visualization with the Portal
The Portal may be used to visualize source catalogs, including the Hubble Source Catalog (HSC; Whitmore et al. 2016), as positions distributed on a displayed image or as a user-defined plot of various source attributes. A number of tutorials have been developed for various science uses, and some are likely to be helpful for JWST data users.
Table 1. Tutorials for using the Portal to explore catalogs
|Catalog cross-match||Perform cross-match between user catalog and the HSC|
|Catalog Filtering||Isolate the red sequence in the galaxy cluster Abell 2390|
|Catalog filtering and outlier detection||Search for variable objects in the dwarf irregular galaxy IC 1613|
|Outlier detection with the HSC||Search for white dwarfs in the globular cluster M4 using the HSC and the CasJobs engine|
JWST engineering database portal
JWST makes a portion of its contemporaneous engineering data available to science users. The engineering telemetry is stored in the Engineering Database (EDB) in the form of time series for thousands of telemetry points on the instruments and the spacecraft, as described in the JWST Archive Manual article on Engineering Data. You may retrieve these data through the Engineering Database Portal, as explained in the article on Using the Engineering Data Portal.
You must have a MyST account and be logged in to search the EDB with the Portal, or use an auth.MAST token to retrieve EDB data with the API.
Community data visualization tools
JWST data may be queried and visualized with a variety of community-based applications, many of which use Virtual Observatory (VO) protocols to access the data. Below is an incomplete list of community, VO-aware tools for visualizing and exploring archived astronomical images, spectra, and catalogs.
Table 2. Community VO-aware tools
|Aladin||Analysis||Interactive sky atlas, capable of overlaying archived images and source catalogs|
|DataScope||Discovery||Position-based search engine for astronomical archives|
|SAOimage/DS9||Analysis||Image display tool, capable of overlaying archived source catalogs|
|SIMBAD||Retrieval||Astronomical catalog search engine|
|SkyView||Discovery||Astronomical image search engine|
|TOPCAT||Analysis||Catalog cross-match, filtering, sub-setting, and visualization tool|
|VizieR||Retrieval||Astronomical catalog search engine|
Fleming, S. W., et al. 2015, AAS, 225, 336.59
Beyond the Prime Directive: The MAST Discovery Portal and High Level Science Products
Whitmore, B., et al. 2016, AJ, 151, 134
Version 1 of the Hubble Source Catalog
MAST Portal Guide
MAST Discovery Portal (web interface)