- JWST Cycle 1 Proposal Opportunities
- JWST Cycle 1 Guaranteed Time Observations Call for Proposals
- • JWST Director's Discretionary Early Release Science Call for Proposals
- • JWST Call for Proposals for Cycle 1
- James Webb Space Telescope Call for Proposals for Cycle 1
- •JWST Cycle 1 Proposal Checklist and Resources
- •JWST Cycle 1 Proposal Policies and Funding Support
- JWST Cycle 1 Proposal Categories
- •JWST Cycle 1 Observation Types and Restrictions
- •JWST Cycle 1 Proposal Preparation
- •JWST Cycle 1 Single-Stream Proposal Process
- •JWST Cycle 1 Special Submission Requirements
- •JWST Cycle 1 Observation Mode Restrictions
- •JWST Cycle 1 Proposal Selection Process
- •JWST Cycle 1 Awarded Program Implementation
- •JWST Cycle 1 Proposal Science Categories and Keywords
- JWST General Science Policies
- • JWST Observing Overheads and Time Accounting Policy
- • JWST Duplicate Observations Policy
- • JWST Science Parallel Observation Policies and Guidelines
- • JWST Observing Program Modification Policy
- • Policies for the Telescope Time Review Board
- • JWST Target of Opportunity Program Activation
- NASA-SMD Policies and Guidelines for the Operations of JWST at STScI
- •Policy 1 - Limitations on the Use of Funds for the Research of General Observers and Archival Research
- •Policy 2 - Data Rights and Data Dissemination
- •Policy 3 - Data Requests and Facilities
- •Policy 4 - Post-Launch Commissioning of JWST
- •Policy 5 - Clarification of Extensions of Exclusive Access Data to Public Affairs Activities
- •Policy 6 - Distribution of JWST Science Data Obtained from Investigations Other Than Those Selected Through the Peer-review Process
- •Policy 7 - NASA Needs for Support for Other Missions
- •Policy 8 - Definition of Observing Time
- •Policy 9 - Allocation of Guaranteed Observing Time to Scientists Selected Under AO 01-OSS-05 and Through NASA-ESA-CSA Agreements
- •Policy 10 - Redistribution of Guaranteed Observing Time Among Observers
- •Policy 11 - Protection of Science Programs Associated With Guaranteed Time
- •Policy 12 - Education and Public Outreach
- Methods and Roadmaps
- JWST Imaging
- • JWST Slit Spectroscopy
- • JWST Slitless Spectroscopy
- JWST High-Contrast Imaging
- •Contrast Considerations for JWST High-Contrast Imaging
- •JWST Coronagraphic Observation Planning
- •JWST Coronagraphic Sequences
- •JWST Coronagraphy in ETC
- •JWST High-Contrast Imaging in APT
- •JWST High-Contrast Imaging Inner Working Angle
- •JWST High-Contrast Imaging Optics
- •JWST Small Grid Dither Technique
- •MIRI-Specific Treatment of Limiting Contrast
- •NIRCam-Specific Treatment of Limiting Contrast
- •NIRISS AMI-Specific Treatment of Limiting Contrast
- •Selecting Suitable PSF Reference Stars for JWST High-Contrast Imaging
- JWST Integral Field Spectroscopy
- JWST MOS Spectroscopy
- JWST Time-Series Observations
- •Overview of Time-Series Observation (TSO) Modes
- •Noise Sources for Time-Series Observations
- •Sensitivity of Time-Series Observation Modes
- •Bright limits of Time-Series Observation Modes
- •Preparing Time-Series Observations with JWST
- •Target Acquisition for Time-Series Observations
- •NIRCam-Specific Time-Series Observations
- •NIRISS-Specific Time-Series Observations
- •MIRI-Specific Time-Series Observations
- JWST Moving Target Observations
- •Moving Target Roadmap
- •Field of Regard Considerations for Moving Targets
- •Instrument-Specific Considerations for Moving Targets
- •Moving Target Recommended Strategies
- •JWST Moving Target Observing Procedures
- •JWST Moving Target Calibration and Processing
- •JWST Moving Target Ephemerides
- JWST Moving Targets in APT
- •JWST Moving Targets in ETC
- •JWST Moving Target Useful References and Links
- •Overheads for Moving Targets
- •JWST Moving Target Policies
- NIRSpec IFU and Fixed Slit Observations of Near-Earth Asteroids
- JWST Parallel Observations
- JWST Target of Opportunity Observations
- Observatory Functionality
- • JWST Position Angles, Ranges, and Offsets
- • JWST Instrument Ideal Coordinate Systems
- JWST Background Model
- • JWST Guide Stars
- • JWST Mosaic Overview
- • JWST Dithering Overview
- JWST Duplication Checking
- JWST Observing Overheads and Time Accounting Overview
- •JWST Observing Overheads Summary
- •JWST Slew Times and Overheads
- JWST Instrument Overheads
- Observing Overheads for NIRCam Imaging
- • JWST Data Rate and Data Volume Limits
- Observatory Hardware
- • JWST Observatory Overview
- • JWST Observatory Coordinate System and Field of Regard
- • JWST Field of View
- • JWST Orbit
- JWST Spacecraft Bus
- • JWST Pointing Performance
- • JWST Telescope
- • JWST Wavefront Sensing and Control
- • JWST Momentum Management
- • JWST Integrated Science Instrument Module
- • JWST Solid State Recorder
- • JWST Target Viewing Constraints
- • Fine Guidance Sensor, FGS
- JWST Exposure Time Calculator Overview
- • JWST ETC New User Guide
- JWST ETC Calculations Page Overview
- •JWST ETC Creating a New Calculation
- •JWST ETC Backgrounds
- •JWST ETC Wavelength of Interest/Slice
- •JWST ETC Batch Expansions
- JWST ETC Strategies
- JWST ETC Target Acquisition
- JWST ETC Outputs Overview
- JWST ETC Workbooks Overview
- JWST ETC Pandeia Engine Tutorial
- • JWST ETC Point Spread Functions
- • JWST ETC Instrument Throughputs
- • JWST ETC Residual Flat Field Errors
- • JWST ETC NIRCam Imaging
- Astronomers Proposal Tool
- • JWST Astronomers Proposal Tool Overview
- APT Workflow
- Additional APT Functionality
- Getting Help with APT
- Other Tools
- Mid Infrared Instrument
- • MIRI Overview
- MIRI Observing Modes
- MIRI Instrumentation
- MIRI Operations
- MIRI Target Acquisitions
- MIRI Dithering
- MIRI Mosaics
- •MIRI MRS Simultaneous Imaging
- MIRI Time Series Observations
- MIRI Predicted Performance
- MIRI APT Templates
- MIRI Observing Strategies
- MIRI Example Programs
- •MIRI Coronagraphy of GJ 758 b
- MIRI Imaging, MIRI MRS, and NIRSpec IFU Observations of SN1987A
- •MIRI and NIRCam Coronagraphy of the Beta Pictoris Debris Disk
- •MIRI IFU and NIRSpec Observations of Cas A
- MIRI MRS Spectroscopy of a Late M Star
- MIRI MRS and NIRSpec IFU Observations of Cassiopeia A
- Near Infrared Camera
- • NIRCam Overview
- NIRCam Observing Modes
- NIRCam Instrumentation
- •NIRCam Field of View
- •NIRCam Modules
- •NIRCam Optics
- •NIRCam Dichroics
- •NIRCam Pupil and Filter Wheels
- •NIRCam Filters
- •NIRCam Coronagraphic Occulting Masks and Lyot Stops
- •NIRCam Filters for Coronagraphy
- •NIRCam Grisms
- •NIRCam Weak Lenses
- NIRCam Detectors
- NIRCam Operations
- NIRCam Dithers and Mosaics
- •NIRCam Coronagraphic PSF Estimation
- •NIRCam Coronagraph Astrometric Confirmation Images
- •NIRCam Apertures
- NIRCam Target Acquisition Overview
- NIRCam Predicted Performance
- NIRCam APT Templates
- NIRCam Observing Strategies
- NIRCam Example Programs
- NIRCam Deep Field Imaging with MIRI Imaging Parallels
- NIRCam Imaging and NIRISS WFSS of Galaxies Within Lensing Clusters
- •NIRCam WFSS Deep Galaxy Observations
- •NIRCam and MIRI Coronagraphy of the Beta Pictoris Debris Disk
- •NIRCam Coronagraphy of HR8799 b
- NIRCam Grism Time-Series Observations of GJ 436b
- NIRCam Time-Series Imaging of HAT-P-18 b
- Near Infrared Imager and Slitless Spectrograph
- • NIRISS Overview
- NIRISS Observing Modes
- NIRISS Instrumentation
- NIRISS Operations
- NIRISS Predicted Performance
- NIRISS APT Templates
- NIRISS Observing Strategies
- NIRISS Example Programs
- NIRISS AMI Observations of Extrasolar Planets Around a Host Star
- NIRISS SOSS Time-Series Observations of HAT-P-1
- NIRISS WFSS with NIRCam Parallel Imaging of Galaxies in Lensing Clusters
- Near Infrared Spectrograph
- NIRSpec Overview
- NIRSpec Observing Modes
- NIRSpec Instrumentation
- •NIRSpec Optics
- •NIRSpec Dispersers and Filters
- NIRSpec Detectors
- •NIRSpec Micro-Shutter Assembly
- •NIRSpec Integral Field Unit
- •NIRSpec Fixed Slits
- NIRSpec Operations
- NIRSpec Dithers and Nods
- NIRSpec MOS Operations
- NIRSpec IFU Operations
- •NIRSpec FS Operations
- •NIRSpec BOTS Operations
- NIRSpec Target Acquisition
- NIRSpec Predicted Performance
- NIRSpec APT Templates
- NIRSpec Multi-Object Spectroscopy APT Template
- •NIRSpec MOS Proposal Checklist
- •NIRSpec MSA Planning Tool, MPT
- NIRSpec MPT - Catalogs
- •NIRSpec MPT - Planner
- NIRSpec MPT - Manual Planner
- •NIRSpec MPT - Plans
- •NIRSpec MPT - Parameter Space
- •NIRSpec MSA Spectral Visualization Tool Help
- •NIRSpec Observation Visualization Tool Help
- •NIRSpec IFU Spectroscopy APT Template
- •NIRSpec Fixed Slit Spectroscopy APT Template
- •NIRSpec Bright Object Time-Series APT Template
- •NIRSpec FS and IFU Mosaic APT Guide
- NIRSpec Multi-Object Spectroscopy APT Template
- NIRSpec Observing Strategies
- •NIRSpec Background Recommended Strategies
- •NIRSpec Bright Spoilers and the IFU Recommended Strategies
- •NIRSpec Detector Recommended Strategies
- •NIRSpec Dithering Recommended Strategies
- •NIRSpec MOS Recommended Strategies
- •NIRSpec MSA Leakage Subtraction Recommended Strategies
- •NIRSpec Target Acquisition Recommended Strategies
- NIRSpec Example Programs
- NIRSpec IFU and MIRI MRS Observations of Cassiopeia A
- NIRSpec BOTS Observations of GJ 1214b
- NIRSpec IFU, MIRI Imaging, and MIRI MRS Observations of SN1987A
- NIRSpec IFU and Fixed Slit Observations of Near-Earth Asteroids
- NIRSpec MOS Deep Extragalactic Survey
- •NIRSpec MOS Observations of NGC 346
- •NIRSpec and MIRI IFU Observations of Cas A
- Understanding Data Files
- Obtaining Data
- Data Processing and Calibration Files
- JWST Data Reduction Pipeline
- • Primer and Tutorials
- • Pipeline User's Guide
- • Software Reference Documentation
- Algorithm Documentation
- • Obtaining and Installing Software
Detailed step-by-step instructions are available for filling out the JWST NIRSpec IFU Spectroscopy APT template.
The NIRSpec integral field unit (IFU) can obtain spatially resolved imaging spectroscopy of a contiguous, extended 3" × 3" area on the sky. To achieve this, the IFU uses specialized optics to reformat the spatial region and direct light to the spectrograph optics, which it shares with the multi-object spectroscopy (MOS) and fixed slit (FS) observing modes. Additional information is available on the IFU hardware and the IFU observing mode pages.
This article presents preparation of a NIRSpec IFU observation using the Astronomer's Proposal Tool NIRSpec IFU template.
Step-by-step APT instructions
We assume the observer has already defined target(s) to be observed, created an observation folder, and loaded the NIRSpec IFU template. Instructions for doing this are presented in the JWST Astronomers Proposal Tool.
The IFU template can be divided into four sections, as shown in Figure 1.
- Section 1: This section shows that the NIRSpec IFU spectroscopy template has been selected, along with a target that was previously defined by the user.
- Section 2: The area contains parameters that are for the proposer's information. The observer cannot edit this section.
- Section 3: In this section the observer enters the target acquisition parameters.
- Section 4: In this section the user defines the science paramerers that determine the specifics of the observation.
Section 3 and 4 are part of the 'NIRSpec IFU Spectroscopy' tab. There are three additional tabs: "Mosaic Properties", "Special Requirements", and "Comments", which are discussed at the end of this article.
IFU template section 1: Generic
IFU template section 2: observation information
The following is included for information only and is generic to all templates. The article APT Observations contains more detailed information on the topics Visit Splitting, Duration, and Data volume.
IFU template section 3: Target Acquisition Parameters
Section 3 in Figure 1 corresponds to the target acquisition (TA) parameters.
For NIRSpec IFU observations there are four options for TA Method 1, MSA target acquisition (called MSATA), the Wide Aperture Target Acquisition (WATA), VERIFY_ONLY, and NONE. The default option for this template is WATA.
Two of the options, MSATA and WATA, perform a target acquisition sequence of imaging and centroiding to make pointing corrections which will result in the science source centered in the science aperture. WATA centers the TA target in the wide aperture to determine a pointing correction to place the science target in the science aperture. MSATA uses reference stars in the MSA to determine the pointing correction. The remaining two TA Method options, NONE and VERIFY_ONLY, forego target acquisition altogether and rely on the pointing accuracy delivered by the guide star acquisition.
A complete description of the target acquisition procedures used to point the telescope with different JWST NIRSpec observing modes are addressed in the NIRSpec Target Acquisition article.
Basically, the current implemented TA procedure starts with placing the science target in the S1600A1 aperture, centering it with onboard software. This method requires less planning effort on the part of the observer but is appropriate only for targets that are point sources or close to point sources. Typical suggested coordinate accuracies for the target are in the order of 100 milli-arcsec. Observers can define four TA parameters in the IFU APT template: the Acquisition Target, Subarray type, the Filter, and the Readout Pattern. The options for Subarray are SUB32, SUB2048, and FULL. The options for TA filter are F110W, F140X, and CLEAR. Detailed information on these filters can be found in the article NIRSpec Dispersers and Filters. The available readout patterns are NRS, and NRSRAPID which define the TA exposure time. Further information on these options can be found in the article NIRSpec Detector Readout Patterns.
When selecting the MSATA option, the target acquisition parameters will be specified at the visit level. MSATA uses reference stars to accurately correct the pointing.
Observers do not need to define reference stars in order to propose for NIRSpec IFU science. That can be deferred until the final program update. The planning parameters will be specified for accepted programs after the MSA-based Target Acquisition is assigned an aperture position angle by the long range planning system. A detailed description of this TA mode is available in the NIRSpec Target Acquisition - MSATA article.
The NIRSpec VERIFY_ONLY method relies only on guide star acquisition performed by the Fine Guidance Sensor (FGS) to derive a telescope pointing. This method is suitable for placing extended objects in the field for IFU observations or for very extended targets with the NIRSpec MOS spectroscopy mode. The precision of this method is limited by the JWST observatory pointing accuracy.
When selecting VERIFY_ONLY as the TA Method, Section 3 looks like Figure 3.
VERIFY_ONLY will obtain an image to verify the pointing during post-analysis. The image, obtained with NIRSpec’s imaging mirror, will provide knowledge of the exact pointing so that it can be aligned with other images and/or data of the field. Under the TA Method VERIFY_ONLY, the proposer needs to define a Filter for the Pointing Verification Image. The options are NIRSpec filters F140X, F110W, and CLEAR, as shown in Figure 4. The Readout Pattern options for this verification image are NRS, NRSRAPID, NRSIRS2, and NRSIRS2RAPID, which are described in further detail in the NIRSpec Detector Readout Modes and Patterns article. When selected, the pointing verification image is taken at the end of the visit, after all science spectroscopy exposures are completed.
By default the Verification Image is taken through an ALLOPEN MSA configuration and the GWA set to MIRROR. The MSA Planning Tool (MPT) can be used to make protected MSA configurations to block shutters on bright targets. The ALLCLOSED MSA shutter configuration option is included. This might not be commonly used, but can be suitable for targets that would saturate in open shutters.
The number of groups for the Pointing Verification Image should be determined using the NIRSpec ETC in single object target acquisition mode with estimates of the brightnesses of sources within the field.
Like VERIFY_ONLY, selecting NONE as the TA Method relies only on guide star acquisition performed by the Fine Guidance Sensor (FGS) to derive a telescope pointing. Unlike VERIFY_ONLY though, no pointing verification images are taken.
IFU template section 4: Science Paramerers
The Science Parameters are defined in section 4 of the IFU Template, as shown in Figure 5. The Science Parameters include the IFU dithering options, and the science exposure specification(s): the spectral configuration used for science, and the detector and exposure configuration options to specify the exposure time.
Dither Parameters and Dither Type
The user needs to define the Dither Type for the IFU observation. Dithering is always recommended for JWST observations. The dither patterns are pre-determined and the available options in the IFU Spectroscopy Template are: NONE, 2-POINT-NOD, 4-POINT-NOD, 2-POINT-DITHER, CYCLING, and SPARSE-CYCLING. These options are in a pull down menu under Dither Type as shown in Figure 6 (Left).
Note that additional information is required for dither types CYCLING, and SPARSE-CYCLING. Figure 6 (Right) shows the case of the CYCLING dither type, where a Size parameter is required with options SMALL, MEDIUM, and LARGE, as well as the Starting Point and the Number of Points. The complete description of each offset pattern is presented in detail in the article NIRSpec IFU Dither and Nod Patterns.
Gratings/Filters and Exposure Configuration
The Exposure Time Calculator (ETC) should be used to determine the best exposure configuration to optimize the SNR of your observation. An exposure is configured by setting the Grating/Filter combination, Readout Pattern, Groups per Integration, and Integrations per exposure.
Users should ultimately use the Exposure Time Calculator Old for all sensitivity calculations.
Recommendations about exposure parameter selection are given in NIRSpec Detector Recommended Strategies.
An exposure specification is created by using the "Add" button located at the bottom of section 4 of the IFU Template as shown in Figure 5. Each line in this field represents a set of exposures acquired with the defined dither option (e.g., a dither option of NONE will result in one exposure, a 4-POINT dither will result in four exposures). The required exposure parameters are listed in Table 1.
Table 1. Description of Science Parameters for a given exposure specification.
Select a Grating/Filter combination from the pull down menu. The article NIRSpec Dispersers and Filters describes all the available combinations for NIRSpec.
|Readout Pattern||The default value is NRS, but the available values are NRS, NRSRAPID, NRSIRS2, and NRSIRS2RAPID. These patterns are described in full detail in NIRSpec Detector Readout Patterns. Select the pattern that best suits your observation.|
|Groups/Int||The number of groups during an integration, where a group is the product of reading the detectors with a specific readout pattern.|
|Integrations/Exp||This represents the number of Integrations during an exposure, where integration is defined as the time between resets.|
|Leakcal||These IFU leakage calibrations can be acquired to mitigate the effects of excess MSA flux from open shutters or leakage.|
This option is available to automatically add calibration exposures to a science exposure. For the IFU template the only options are NONE or WAVECAL. NONE is the default and is recommended because Autocals can add significant overhead to an observation.
NIRSpec's IFU may be used to obtain data for a region larger than its 3 × 3 arcsec size by creating a mosaic pattern. The use of APT's mosaic tool is described in the article NIRSpec FS and IFU Mosaic APT Guide.
A variety of observatory level special requirements may be chosen.
The comments field should be used only to record observing notes. They will become part of the APT file and therefore of the submitted proposal.
This page has no comments.