JWST Resources

We've collected below a list of resources you may find useful
in familiarizing yourself with JWST proposal tools and preparing your Cycle 1 proposal.

Please email us at jwst.texas@gmail.com if you find any problems with the links on this page.

Software and Tools for Observation Preparation

MyST Create an account to access the ETC (and save your work) and the JWST Help Desk
APT This is APT v2020.1.1, which can be used to prepare proposals. The final version (v2020.2) for Cycle 1 will be released March 5, 2020. Final submission of all Cycle 1 proposals must use APT v2020.2
ETC To save your workbooks and share with collaborators, Login with your MyST account and click "Proceed"
AstroConda The JWST visibility and background tools are written in Python and require packages and libraries that are all included in the AstroConda Python distribution
JWST General Target Visibility Tool (GTVT) Command-line Python tool that provides quick-look assessments of target visibilities and position angles for all JWST instruments
JWST Coronagraphic Visibility Tool (CVT) A GUI-based target visibility tool for assessing target visibilities and available position angles versus time relative to the MIRI and NIRCam coronagraphic masks
JWST Backgrounds Tool (JBT) Command line tool that accesses the JWST background models to return the total background intensity and its components as a function of time.
JWST Interactive Sensitivity Tool (JIST) Provides a quick look into feasibility of planned observations prior to in-depth work with the ETC
NIRSpec Observation Visualization Tool (NOVT) Python application that provides a simultaneous view of both NIRSpec and NIRCam fields of view on a given sky position, for assistance in planning NIRCam pre-imaging for NIRSpec.
NIRSpec MSA Spectral Visualization Tool (MSAViz) Allows the user to visualize the layout of MOS spectra on the NIRSpec detectors, given a particular filter, disperser, and MSA shutter configuration
NIRSpec MSA Planning Tool (MPT) Used for the preparation of NIRSpec multi-object spectroscopy observations, part of the APT
WebbPSF Tool Generates accurate point-spread functions for JWST instruments. WebbPSF is used within the ETC to generate PSFs, but the full tool provides users with more flexibility.
Mirage Python code that can be used to generate simulated NIRCam, NIRISS, or FGS imaging data
Awesimsoss Simulates scenes generated by the NIRISS Single Object Slitless Spectroscopy mode

Workshop in a Box

STScI has collected the training and support materials that were presented during the 2019 Master Class workshop into a "Workshop in a Box". These materials include the plenary talks, Master Class "homework" assignments used for practice, hands-on exercises, etc. You can download all resources as a zipped file, or explore them by topic.

In the following sections of this page, we expand on the materials and topics that are available in the Workshop in a Box.

Plenary Talks

The following five talks were presented at the 2019 Master Class workshop at STScI

Topic Description
JWST Documentation ("JDox") An introduction to the workings and theory behind JDox
Exposure Time Calculator (ETC) How it's run, How it's set up
Astronomer's Proposal Tool (APT) Basic usage and some other tools
Ancillary Tools Visibility tools, etc.
JWST Policy Deadlines, available hours, proposal sizes/types, review process

Observing Modes, Exercises, and Science Use Cases

The following sections provide links to more information about the JWST observing modes. Some of the modes were also featured as part of the STScI Master Class, and so introductory presentations, exercises, and solutions are also available.


While imaging was not directly covered by the Master Class, many of the resources and exercises below involve imaging in one capacity or another. Imaging is available with the following instruments:

  • NIRCam (0.6 - 5.0 um)
  • MIRI (5.6 - 25.5 um)
  • NIRISS (0.8 - 5.0 um) (only available for coordinated parallel observations)
See the Imaging Roadmap on JDox for a step-by-step guide through the process of designing a JWST imaging observing program.

Slit Spectroscopy

Slit Spectroscopy is available with NIRSpec and MIRI. In preparing a JWST slit spectroscopy observing program, you must plan for your target acquistion, choose dither patterns, and calculate exposure times for both your acquisition and science observations. See the Slit Spectroscopy Roadmap on JDox for a step-by-step guide.

Wide Field Slitless Spectroscopy

Wide field slitless Spectroscopy (WFSS) is available with NIRISS (0.8 - 2.2 um) and NIRCam (2.4-5.0 um). See the Wide Field Slitless Spectroscopy Roadmap for a step-by-step guide on designing a JWST slitless spectroscopy observing program. This guide walks users through recommended observing strategies for both instruments, blocking filters, direct image and grism sensitivities, dithering, readout patterns, and more.

Slitless spectroscopy was also an observing mode presented during the Master Class. The related resources, exercises and solutions are available here:

Slitless Spectroscopy Presentation
Slitless Spectroscopy Activity Walkthrough
Slitless Spectroscopy APT files: NOTE – APT files include solutions. The exercises involve creating them from scratch.
Slitless Spectroscopy Materials for Activities:


Mosaicking observations allows the observer to cover an area larger than an individual instrument field of view. Mosaic observations are specified in the APT, and are defined by a single coordinate, an assumed tile footprint (size and orientation), and a designated number of rows and columns of the tile footprint. See the Mosaic Overview for more information about specifying mosaics. The following APT science templates allow mosaics:

  • NIRCam Imaging
  • NIRCam Wide field slitless spectroscopy
  • MIRI Imaging
  • MIRI Medium resolution spectroscopy (IFU)
  • MIRI Low resolution spectroscopy
  • NIRSpec IFU
  • NIRSpec Fixed slit
  • NIRISS Imaging
  • NIRISS Wide field slitless spectroscopy

When preparing mosaic observations, it is very useful to view the defined mosaics in the Aladin viewer in APT to assess the overall shape and coverage!

Mosaics were also presented during the Master Class. The related resources, exercises and solutions are available here:

High-Contrast Imaging

High-Contrast Imaging (HCI) allows observers to obtain images of faint sources located near bright point sources. The available modes for HCI are:

HCI observations involve some additional considerations and preparation. See the following links for more information about designing a JWST HCI observing program:

High-contrast imaging was also an observing mode presented during the Master Class. The related resources, exercises and solutions are available here:

HCI Presentation – Science cases, HCI modes and use cases, a walk through the HCI Roadmap
HCI exercises – Reference star selection, Coronagraphy Visibility Tool, timing constraints, etc.
Example Science Programs for Coronagraphy:
NIRISS AMI Presentation
NIRISS AMI Exercises – with supporting slides and answers
Example Science Program for NIRISS AMI:
PanCAKE Demo – ETC limitations and high(er) fidelity calculations
Additional Useful Links:

Integral Field Spectroscopy

Integral field spectroscopy is the process of dissecting an astronomical scene into multiple spatial components and dispersing each component with a spectrograph in order to provide spatially-resolved spectroscopic information. JWST has two integral field units (IFUs):

  • MIRI Medium Resolution Spectroscopy – R ~ 1500-3500, 5-28um, FOV=7"x8"
  • NIRSpec IFU Spectroscopy – R ~ 100,1000,2700, 0.6-5.3um, FOV=3"x3"

IFU observations involve some important considerations, including target acquisition, PSF variations, dithering, and whether background observations are required to meet the science goals. See the IFU Roadmap for a step-by-step guide through the process of designing an observing program using one or both of JWST's IFUs.

IFU spectroscopy was also an observing mode presented during the Master Class. The related resources, exercises and solutions are available here:

Multi-Object Spectroscopy

JWST Multi-object spectroscopy (MOS) uses NIRSpec's micro-shutter assembly (MSA) to obtain simultaneous spectroscopy of multiple sources in a single exposure. The MSA shutter configuration is set using the NIRSpec MSA Planning Tool (MPT), found within the APT. At the time of proposal submission, observers submit a set of planning visits with placeholder pointings and MSA shutter configurations that will be representative of the pointing and configurations after the observations are scheduled. Once the observations are scheduled and an aperture position angle has been assigned, users will re-run the MPT to design the final MOS observations.

The MSA shutters are very small, 0.2" wide. Pre-imaging with high astrometric accuracy (5-15 mas relative astrometry) is required to position the shutters accurately onto science sources. Images obtained using HST/ACS or HST/WFC3 UVIS within the past ten years should have this level of accuracy. In some cases, the planning of the NIRSpec spectroscopy will require NIRCam observations, which are specified using the NIRCam imaging tempate in the APT.

The following links provide more information about planning and executing MOS observations with JWST:

Multi-object spectroscopy was also an observing mode presented during the Master Class. The related resources, exercises and solutions are available here:

Time Series Observations

Time series observations provide a way to monitor time variable phenomena, with observations optimized for detecting faint variations in flux over short or long timescales. Available TSO-specific instrument modes are:

  • NIRISS Single Object Slitless Spectroscopy (SOSS)
  • NIRCam Time-Series Imaging
  • NIRCam Grism Time Series
  • NIRSpec Bright Object Time-Series Spectroscopy (BOTS)
  • MIRI Imaging TSOs
  • MIRI Low Resolution Spectroscopy (LRS)
  • MIRI Medium Resolution Spectroscopy (MRS)

A few changes are made to the instrument setup and data processing to provide the highly stable conditions needed for long duration staring at TSOs:

  • Dithering is disabled
  • Target acquisition is enabled (mandatory for some modes)
  • Exposures can take longer than 10,000 s
  • High gain antenna moves are allowed during the exposure
  • Data are processed via a dedicated pipeline branch

For more information and a step-by-step guide describing how to prepare time series observations with JWST, see the TSO Roadmap.

Time series observations were also presented during the Master Class. The related resources, exercises and solutions are available here:

Moving Targets

JWST will be able to observe Solar System (moving) targets, with high sensitivity and spatial resolution, through imaging as well as low and medium resolution spectroscopy. See the Moving Target Roadmap for a step-by-step guide through the process of creating moving target observations with JWST.

Moving target observations were also presented during the Master Class. The related resources, exercises and solutions are available here:

Moving Targets Presentation
Moving Targets Exercises
Moving Targets APT file with solutions
NOTE – APT file includes solutions. The exercise involves creating it from scratch.
Moving Targets Exercise Solutions

Parallel Observing

Target of Opportunity

A target of opportunity (ToO) refers to requested JWST observations that are linked to an event that may occur at an unknown time. ToO targets include objects that can be identified in advance but which undergo unpredictable changes, as well as objects that can only be identified in advance as a class (e.g., novae, supernovae, gamma ray bursts, tidal disruption flares, newly discovered comets, etc.). See the ToO Roadmap for a step-by-step guide through the process of designing a target of opportunity program with JWST.

Note that, due to their disruptive nature, ToO programs can incur significant additional overheads if activated on short turnaround times. See the Policy Plenary talk for more information.