Getting Started Guide
A general guide to getting started with planning JWST observations. See method-specific roadmaps for more detailed information about individual observing modes.
The steps below suggest a general workflow, but depending on your science goals and background, the steps and order may vary.
Know the deadlines
The Cycle 1 GO/AR proposal deadline is TBD
Become familiar with JWST capabilities, terminology, and documentation
- Become familiar with JWST Documentation (JDox). Consider starting with an overview on the Observatory and the 4 instruments: Mid Infrared Instrument (MIRI), Near Infrared Camera (NIRCam), Near Infrared Spectrograph (NIRSpec), and Near Infrared Imager and Slitless Spectrograph (NIRISS).
- Learn about MULTIACCUM detector readouts to understand how to specify the exposure time for your JWST observation.
- Perform a quick feasibility check with the JWST Interactive Sensitivity Tool (JIST).
- Familiarize yourself with the many tools available to you when writing your proposal, including, but not limited to, the Exposure Time Calculator, the Astronomer's Proposal Tool, JWST Target Visibility Tools, WebbPSF, and the Background Modeler.
- Identify instrument(s) and observing mode(s) you need to address your science goals. The observing methods and roadmaps summarize JWST observing capabilities and step-by-step observing guides. You can compare and contrast the unique observing modes from each instrument that support these different types of observations.
- Familiarize yourself with the documentation for your chosen instrument mode, paying particular attention to things such as:
- whether operations such as dithering, target acquisition, mosaicking, etc., are required, encouraged, or not permitted for that mode;
- whether you should consider using a subarray for your observations;
- whether your chosen mode is multi-phase, e.g., the NIRSpec multi-object spectroscopy mode may require NIRCam pre-imaging to obtain high quality astrometry for your target list.
- Read the JWST Recommended Observing Strategies for your chosen instrument mode for advice on which observing parameters to pick to optimize your science program.
- Read through an example science program for your chosen instrument mode (if available) to see a complete overview of the proposal planning process, including how to construct an exposure time calculator (ETC) workbook and complete an Astronomers Proposal Tool (APT) observing template.
Determine if your targets can be observed
The entire sky is available to JWST observations over the course of a year, but only approximately 40% is accessible at any given time. Targets that need to be observed at a particular time, time separation, or aperture position angle on the sky may have significantly constrained visibility or may even be unschedulable. There is a simple tool to perform a quick assessment of schedulability of proposal targets prior to developing an APT proposal. Much of this is already integrated into APT, so accessing the separate tool may be unnecessary for most users. There are more specialized tools to help users plan coronagraphy observations and pre-imaging observations for NIRSpec MOS mode, and there is also a tool to compute and visualize the background levels versus date for a given target.
- Check whether your target(s) is already planned to be observed. Duplicate observations are allowed only under certain circumstances.
- If there is a specific timing window or position angle needed for your target, use the Target Visibility Tools to ensure that the target is visible by JWST during that window.
- Use the JWST Interactive Sensitivity Tool (JIST) for an estimate of the signal-to-noise value for a given source flux density and exposure time for your chosen instrument observing mode(s).
- If you are planning to observe particularly faint targets, assess whether your observations will be background limited. The Backgrounds Tool will be helpful for visualizing how the background changes over time and how significantly the target visibility is constrained by this.
Use the Exposure Time Calculator to determine observing parameters
- The Exposure Time Calculator (ETC) should be used to determine the appropriate exposure parameters (e.g., Readout pattern*, Groups per integration, Integrations per exposure, and Exposures per specification) needed to achieve the desired signal-to-noise ratio for your target. Video tutorials and a new user guide for the ETC are available to help you get started with the ETC.
- Define your source(s) and scene(s) in the ETC.
- Select an instrument and observing mode in the ETC.
- Select instrument parameters within the instrument configuration pane on the ETC calculation page.
- Run an ETC calculation on your defined scene.
- Adjust the exposure time via the Groups per integration, Integrations per exposure, and/or Exposures per specification parameters until you obtain your desired signal-to-noise ratio (SNR):
- The instrument-specific observing strategies articles provide recommendations for how to split exposure time into Groups per integration, Integrations per exposure, and/or Exposures per specification, based on observing mode, science use case, avoiding saturation, and minimizing cosmic ray hits on the detector.
- ETC batch expansion is an efficient way to determine the SNR for a range of possible values for a given exposure parameter.
* Bold italics style indicates words that are also parameters or buttons in software tools (like the APT and ETC). Similarly, a bold style represents menu items and panels.
Prepare your proposal in the Astronomers' Proposal Tool
- The Astronomers' Proposal Tool (APT) is used to set up your observing program and submit your proposal. Training examples and video tutorials are available to help you get started.
- Fill out your proposal information in APT, e.g., Title, Abstract, Proposal Category, etc.
- Enter your proposed target(s) (or OFFSET targets if required for your observing case). Note: for the special case of the NIRSpec multi-object spectroscopy mode, targets are not input directly, but are created by the NIRSpec MSA Planning Tool (MPT). If using this OBSERVING MODE, make sure to read the extensive MPT documentation.
- Define your observing parameters in the APT Observation Template(s) relevant for your chosen instrument(s) and OBSERVING MODE(s). Here you would enter the exposure specifications (i.e., Groups per integration, Integrations per exposure, and/or Exposures per specification) that you determined via the ETC. If desired, add cross references to your relevant ETC workbook in the "ETC wkbk. calc" field (strongly recommended if your program requires a target acquisition).
- Make sure to define any special requirements (e.g., timing constraints, moving target, background limited observation).
- View an observation with the Aladin visualizer tool.
- Run the Visit Planner to ensure your observations are schedulable, and resolve any errors.
- Run Smart Accounting to determine whether overheads associated with your program can be minimized.
- In some cases it may not be possible to fully specify a proposal at the time of submission (e.g. to resolve all errors and warnings in APT). Proposals that may be exempted from the nominal single-stream process will be described in the special submission requirements section of each call for proposals.
Write your science proposal
- Create the PDF attachment of the proposal narrative, which includes a number of required text sections such as the Scientific Justification and Technical Justification. As a reminder, the JWST proposal review will follow a dual anonymous process, and proposals must conform with the guidelines presented in the Call for Proposals.
Submit your JWST proposal
- Attach the PDF of your science justification to your APT template.
- Preview the entire proposal by selecting the APT PDF Preview tool. This view will merge the information provided in APT along with the PDF attachment, and is what the Telescope Allocation Committee (TAC) will review.
- Submit your completed proposal with APT. Select the APT Submission Tool in the top tool bar and follow the instructions. In the Submission Log window you will see a message giving the time of the submission, the assigned proposal ID (if a new proposal), and the submission status.
- After the initial submission, proposals can be re-submitted as needed (up to the stated deadline). Resubmitting does not change the proposal number received upon the initial submission.
After you submit your proposal, all investigators will receive an automatic email acknowledgment that the submission was received successfully. If you do not receive that email within minutes of your submission, please check the APT Submission Log window for a problem. In addition, all investigators will receive an additional email indicating whether your proposal was successfully processed after the submission deadline.
If you do not receive this acknowledgement within 72 hours of the deadline, please submit an incident to the JWST Help Desk, as your submission was not received and the TAC will not see your proposal; please provide the submission ID information from the APT Submission Log window. If there are any problems associated with your PDF attachment or APT information submitted, you will be contacted by email separately.
Notification of your proposal's status (approved or rejected) generally occurs within ~4 weeks of the Telescope Allocation Committee meeting.
Next steps for approved programs
Successful JWST observing proposals will be reviewed by a STScI instrument scientist and program coordinator. Programs may require adjustments or revisions after the award. Proposers should submit programs that are executable, but STScI expects iterative optimization between the institute and the PI of accepted cycle 1 programs. The instrument scientist and program coordinator will iterate with proposers to finalize the observations in accordance with TAC recommendations, under the approval of the STScI director.