Step-by-Step APT Guide for MIRI MRS Spectroscopy of a Late M Star
Instructions are provided for filling out JWST APT observing template for the MIRI MRS Spectroscopy of a Late M Star Example Science Program, where MIRI-MRS is used to obtain a medium-resolution spectrum of a late M star.
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 "MIRI IFU Spectroscopy of a Late M Star" Example Science program.
A filled out APT file can be downloaded here for reference. The APT file was created with version 27.1 There may be inconsistencies or additional warnings or errors with other versions of APT.
Fill Out Proposal Information
Main article: JWST Astronomers Proposal Tool overview
After opening APT, we selected "New JWST Proposal" under the "New Document" pull-down menu just above the tree editor at the bottom-left of the top tool bar. On the active GUI window for the Proposal Information entry in the tree editor, we entered Title, Abstract, and Category of the proposal and kept Cycle number at its default value. We updated Scientific Category to Stellar Physics and added the following Science Keywords: Cool Stars, Low-Mass Stars. In Alternate Category, we entered Planets and Planet Formation.
Note that APT issues errors in the Proposal Information page since a PDF science justification is not uploaded. For the purposes of this tutorial, it is fine to ignore these warnings. However, for proposals submitted in response to the Call for Proposals, ensure that you upload a PDF of your science justification prior to submission.
Enter Proposed Targets
Main article: APT Targets
Target information is entered in the active GUI window for the "Targets" entry in the tree editor. In this active GUI window, we clicked on the "New Fixed Target" button. We entered SOMESTAR in the field for Name in the Proposal, and selected Star for Category. We entered the coordinates for this source: RA = 04 30 0.0000, Dec = +25 00 0.00. Near the Description field, we clicked the "+/-" button which opens a list of approved keywords and selected M stars.
Main article: APT Observations
In the active GUI window for the "Observations" entry in the tree editor, we clicked on the "New Observation Folder" button to specify the observing parameters for our program. In the Label field, we entered Late M Star. Note that while this label is not required, setting it is useful for visually organizing your observation folders in the tree editor when potentially many targets and/or instrument setups are used.
We clicked "Observation 1" in the tree editor to open the observation template to be filled out. In the Instrument pull-down menu in the active GUI window, we selected MIRI, and then we selected the MIRI Medium Resolution Spectroscopy template in the Template pull-down menu. In the Target pull-down menu, we selected the target we defined above, SOMESTAR.
Complete APT Observation Template for MIRI MRS
An MRS Target Acquisition is chosen, with the Acquisition Target set to SOMESTAR (it is also possible to set the Acquisition Target to a nearby target; the TA pull-down menu allows both options), the Acquisition Filter set to FND, Acquisition Readout Pattern set to FAST, Acquisition Groups/Int set to 5.
As discussed in the parent article and the Step-by-Step ETC Guide, a set of observations will be taken using all 3 grating settings for MIRI-MRS: SHORT, MEDIUM, and LONG. Both short and long wavelength detectors for the MRS are used. In order to set the dither pattern, we clicked the Add button under the Dithers pane, and then a 4-point dither pattern optimized for a point source is chosen, with the primary channel set to All, in the negative direction.
After the Dithers pane in the active GUI window, the Simultaneous Imaging drop-down menu option was set to YES. To the side of this, the Imager Subarray drop-down menu was set to FULL. Under this in the Exposure Parameters pane, we clicked Add 3 times, each corresponding to the 3 available MRS grating settings. One click of the Add button here brings up 3 rows: one for the MIRI Imager, the next for the MRS long-wavelength detector, and the other for the MRS short-wavelength detector. Under the Wavelength Range column, for the first triplet of rows, the value was set to SHORT (A) for MRSLONG and MRSSHORT rows. For the second and third triplets of rows, the values were set to MEDIUM (B) and LONG (C), respectively. Under the Filter column, in the Imager rows, F560W was selected. Under the Readout Pattern column, FAST was selected. Under the Groups/Int column, the values were set to 27, 37, and 32 for the SHORT, MEDIUM, and LONG gratings, respectively. Under the Integrations/Exp column, the values were set to 1, 3, and 5, respectively. The values of Groups/Int and Integrations/Exp were determined by the iterative procedure described in the Select Instrument Parameters section of the Step-by-Step ETC Guide. Under the Exposures/Dith column, the value was set to 1 for all rows. Under the Dither column, the value was set to Dither 1 for all rows. The entries under the Total Dithers, Total Integrations, and Total Exposure Time columns are determined by APT from the previous entries. The ID number of the ETC workbook used to calculate ETC parameters should be provided in the ETC Wkbk.Calc ID column, though an ETC workbook ID is not available for the Late M Star ETC sample workbook. The button in the last column, ETC, launches the JWST ETC.
Run Visit Planner
Main article: APT Visit Planner
To determine the visibility window of our proposed observation, we ran the Visit Planner Tool. First, we click an observation in the tree editor. Then we click the Visit Planner button in the top tool bar, which changes the view in the active GUI window. Then we click the Run All Tools button at the right in the top tool bar. This shows us the observing window(s) for this target over the next ~19 months. APT assures us that all visits are schedulable.
Run Smart Accounting
Main article: APT Smart Accounting
To minimize excessive overheads, we ran Smart Accounting from the Visit Planner page by clicking the "Run Smart Accounting" button beside the Charged Time field in the active GUI window of the Proposal Information entry in the tree editor. The charged time for the observing program, including exposure time and overheads, is now accurately calculated.