Instructions are provided for filling out the JWST APT observing template for the Galaxies in Lensing Clusters example science program, where NIRISS WFSS is a prime observing mode and NIRCam imaging is executed as a coordinated parallel observation.

See also: NIRISS Wide Field Slitless Spectroscopy, NIRISS WFSS Template APT Guide, APT Coordinated Parallel Observations, JWST APT Video Tutorials

The Astronomer's Proposal Tool (APT) is used for submitting JWST proposals. There are multiple components to an APT submission: generic proposal information, target information, and exposure specifications for the proposed program. This guide discusses how to fill out the APT observing template for the "Using NIRISS WFSS and NIRCam Imaging to Observe Galaxies Within Lensing Clusters" example science program.

Fill out proposal information

After opening APT, select New JWST Proposal under the New Document pull-down menu. On the Proposal Information page, enter Title, Abstract, and Category of the proposal and keep Cycle number at its default value. 

Enter proposed targets

See also: APT Targets

Target information is entered by selecting Targets in the tree editor, which provides options in the active GUI window. For this example, choose the New Fixed Target button, enter MACSJ0416.1–2403 in the field for Name in the Proposal, and select Clusters of Galaxies for Category. Enter the coordinates for this source: RA = 04 16 9.40, Dec = -24 04 04.00. Near the Description field, click the "+/-" button which opens a list of approved keywords and select Rich Clusters.

Observations

See also:: APT Observations, APT Coordinated Parallel Observations

Select Observations in the tree editor, then click on the New Observation Folder. In the Label field, enter MACSJ01416.1–2403 NIRISS WFSS Prime NIRCam Imaging Parallel. Note that while this label is not required, setting it is useful for visually organizing your observation folders when potentially many targets and/or instrument setups are used.

Click Observation 1 in the tree editor to open the observation template to be filled out. In the Prime Instrument pull-down menu, select NIRISS, and then select the NIRISS Wide Field Slitless Spectroscopy template in the Template pull-down menu. Check the Coordinated Parallel checkbox and select NIRISS WFSS-NIRCam Imaging in the pull-down menu. In the Target pull-down menu, select the target defined above, MACSJ01416.1–2403.

Complete APT observation template for NIRISS WFSS

See also: NIRISS WFSS Template APT Guide, NIRISS WFSS Dithers, NIRISS WFSS Recommended Strategies, JWST Coordinated Parallels Custom Dithers

As discussed in the parent article and the step-by-step ETC guide, a set of observations will be taken through 3 filters: F115W, F150W, and F200W. Both the GR150C and GR150R grisms are used, with a 9-step custom dither pattern for coordinated parallel observations. In the NIRISS WFSS template, a direct image is automatically taken before and after each set of dithered grism exposures. An exposure sequence through a NIRISS filter is thus:

Direct Image → 9 × GR150C → Direct Image

Direct Image → 9 × GR150R → Direct Image

In the Science (Grism) Exposures panel, select 9-POINT-MEDIUM-NIRCam from the Dithers pull-down menu. Click the Add button to add an entry to the Sequences dialog. Select GR150C in the Grism field and F115W in the Filter field and keep the default Readout Pattern of NIS. Enter 23 in the Groups/Int field and 1 in the Integrations/Exp field ("Sequence" #1). As discussed in the step-by-step ETC guide, these exposure specifications will provide the desired signal to noise ratio (SNR) for the WFSS observation.

Though an option exists in APT to select BOTH grisms when specifying parameters in the Sequences dialog, this would result in a single sequence in which you would have to specify the NIRCam setup in parallel. As the CANUCS program wishes to observe in two separate short-wavelength/long-wavelength pairs of NIRCam filters for each NIRISS blocking filter, specify separate GR150C and GR150R exposure sequences.

Note that entering a grism exposure in the Science (Grism) Exposures panel automatically adds a blank entry in the Direct Image Exposure Parameters panel, where the filter will automatically match that of the WFSS exposure. In the All Exposures Display panel, the order of exposures is listed. The entries of these fields cannot be edited directly. Instead, any updates made in the Science (Grism) Exposures and Direct Imaging Exposure Parameters panels are propagated to All Exposures Display.

In the Direct Image Exposure Parameters panel, enter 13 in the Groups/Int field and 1 in the Integrations/Exp field ("Direct Images" #1). Do not change the Two Extra Dithers default of "NO" since that option is only recommended for the GRISM = BOTH selection in the Sequences dialog. As shown in the step-by-step ETC guide, 4 coadded exposures from one NIRISS filter will produce the desired SNR for the imaging observation. The All Exposures Display panel shows the first exposure sequence in "Exposures" #1: Direct Image → 9 × GR150C → Direct Image.

To enter the exposure parameters for the GR150R Grism for the F115W filter, highlight "Sequences" 1 in the Science (Grism) Exposures panel, click Duplicate, and update the Grism pull-down of this new entry to GR150R. The Direct Images panel is automatically updated to have the same exposure specifications of the direct image of the duplicated exposure ("Direct Images" #2), requiring no additional edits. Exposure 2 in the All Exposures Display panel shows the exposure sequence for this set of direct image and WFSS exposures.

Repeat this procedure for the F150W filter (Exposures #3 - 4) and F200W filter (Exposures #5 - 6), using the same exposure specifications for these filters (Science (Grism) Exposures: 23 Groups/Int and 1 Integrations/Exp; Direct Images Exposures Parameters: 13 Groups/Int and 1 Integrations/Exp).

Complete APT template for parallel NIRCam imaging observation

See also: NIRCam Imaging, NIRCam Imaging APT Template, JWST Parallel Observations, NIRCam Detector Readout Patterns

NIRCam imaging exposures will be observed in parallel in this example program. Since each WFSS observation consists of 3 exposure specifications (Direct Image → 9 × GR150 → Direct Image), the associated NIRCam imaging observation has to also be specified as 3 exposures. Since the primary instrument determines the total integration time per exposure, the exposure time for the NIRCam observations (specified by readout pattern, the number of groups and number of integrations) must not exceed that of the NIRISS exposure. APT will issue an error if the exposure time exceeds that of the prime exposure. For each WFSS observation, NIRCam imaging observations are taken in the short wavelength channel and long wavelength channel. 

To specify the exposure parameters for these parallel observations, click on the NIRCam Imaging tab. In the Module pull-down menu, select ALL and ensure that FULL is selected in the Subarray pull-down menu.

In this program, NIRCam images are obtained for 12 filters, 6 in the short wavelength channel (F090W, F115W, F150W, F182M, F210M, F140M) and 6 in the long wavelength channel (F277W, F250M, F300M, F335M, F360M, F410M). The NIRCam images taken in parallel with the NIRISS exposures all use the MEDIUM8 Readout Pattern. 

Click Add to add an entry to the observing template. Then, select F090W for the Short Filter and F227W for the Long Filter. Since this exposure will be observed simultaneously with the NIRISS direct image, select MEDIUM8 for Readout Pattern, 5 Groups/Int, and 1 Integrations/Exp (Exposure #1). 

Clicked Duplicate to add an entry that will be observed simultaneously as the set of WFSS dithered exposures. Notice that the number of dithers is set to 9 by default, matching the dithering of the prime observing mode. This field can not be updated. Keep MEDIUM8 Readout Pattern and 1 Integrations/Exp. Since this exposure is longer, increase the Groups/Int to 9 (Exposure #2).

Click Duplicate to add a NIRCam entry that corresponds to the NIRISS direct image after the first set of dithered WFSS exposures. Update the Groups/Int to 5, so that this entry matches the first entry in the NIRCam sequence (Exposure #3). The set of 3 NIRCam Imaging exposures that are to be observed in parallel to the first set of the NIRISS WFSS exposure sequence in the F115W filter (Direct Image → 9 × GR150C → Direct Image) are now fully specified in Exposures #1 - 3.

Repeat the procedures above to create a set of NIRCam imaging observations for the remaining sets of NIRISS WFSS observations, using the following NIRCam filter combination in the short/long filters: F115W/F250M (Exposures #4–6), F150W/F300M (Exposures #7–9), F182M/F335M (Exposures #10–12), F210M/F360M (Exposures #13–15), and F140M/F410M (Exposures #16–18).

Define special requirements

Do not define any APT Special Requirement for this program.

Run Visit Planner

To determine the visibility window of the proposed observation and ensure that guide stars can be found, run the Visit Planner Tool, by clicking the Visit Planner icon in the top tool bar. Then, select Update Display in the resulting active GUI window. The Visit Planner will return with a confirmation that the observation is schedulable (green check on the selected observation) and shows the observing window(s) for this target over the next ~19 months. 

Run Smart Accounting

To minimize excessive overheads, run Smart Accounting from the Visit Planner page by selecting the Run Smart Accounting option. The charged time for the observing program, including exposure time and overheads, is now accurately calculated.