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.
Example Science Program #28 APT Guide
Dated material
This example program was constructed pre-launch, and details may be out of date with actual observatory performance. However, it still provides a useful example for training purposes.
Please refer to JWST Example Science Programs for more information.
On this page
See also: MIRI Medium Resolution Spectroscopy, MIRI MRS APT Template, 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 MIRI MRS Spectroscopy of a Late M Star example science program.
A filled out APT file can be accessed via the main menu via File → JWST Example Science Proposals → MIRI → 28 MIRI MRS Spectroscopy of a Late M Star in APT. The APT file was created with version 2020.4.1. There may be inconsistencies or additional warnings or errors with other versions of APT.
Fill out proposal information
See also: JWST Astronomers Proposal Tool overview
Words in bold are GUI menus/
panels or data software packages;
bold italics are buttons in GUI
tools or package parameters.
Enter proposed targets
See also: APT Targets
Target forms are accessed by clicking on Targets in the tree editor. In this active GUI window, you can use the Fixed Target Resolver to have a search done on coordinates or "Object Name", or click on the New Fixed Target button to open the fixed target form. For this example, use SOMESTAR as a New Fixed Target. In the Name in the Proposal field, enter SOMESTAR, and for Category, select Star. The J2000 Coordinates entered are RA = 04 30 0.0000, Dec = +25 00 0.00. For Description, click the +/- button which opens a list of approved keywords and select M stars.
Observations
See also: APT Observations
In the active GUI window for Observations, click on the New Observation Folder button to specify the observing parameters for the program. In the Label field, enter 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.
Click Observation 1 in the tree editor to open the observation template to be filled out. In the Instrument pull-down field in the active GUI window, select MIRI, and then select MIRI MRS APT Template in Template. For Target, select SOMESTAR.
Filling out the APT observation template for MIRI MRS
See also: MIRI MRS APT Template, MIRI MRS Target Acquisition, MIRI MRS PSF and Dithering, MIRI MRS Simultaneous Imaging, MIRI MRS Recommended Strategies
Target acquisition
In the Target Acquisition Parameters panel, Acq Target is set to SOMESTAR (it is also possible to set the Acq Target to the target, as done in this example, or another nearby target), Acq Filter to FND, Acq Readout Pattern to FAST, and Acq Groups/Int set to 6.
MRS parameters
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 (A), MEDIUM (B), and LONG (C). Both short and long wavelength detectors are used.
The Primary Channel was set to ALL.
In order to set the dither pattern, click the Add button under the Dithers panel, and choose a 4-Point dither pattern optimized for a POINT SOURCE in the NEGATIVE direction.
The Simultaneous Imaging parameter was set to YES with Imager Subarray set to FULL.
In the Exposure Parameters panel, click Add 3 times, each for the 3 available MRS grating settings. One click of the Add button brings up 3 rows: one each for the MIRI imager, MRS long wavelength detector, and 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, F1130W was selected.
Under the Readout Pattern column, FASTR1 was selected.
Under the Groups/Int column, the values were set to 27 and 59 for the SHORT (A) and MEDIUM (B) gratings, respectively. For the LONG (C) grating, for "MRSSHORT" the value is set to 49, while for "MRSLONG" the value is set to 98. For the "IMAGER", the values are set to 27, 59, and 98 for the SHORT (A), MEDIUM (B), and LONG (C) gratings, respectively.
For the Integrations/Exp column, the values were set to 1 except for "MRSSHORT" for the LONG (C) grating, where the value is set to 2.
The values of Groups/Int and Integrations/Exp were determined by the iterative procedure described in 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.
Entries under the Total Dithers, Total Integrations, and Total Exposure Time columns were 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
See also: APT Visit Planner
To determine the visibility window of the proposed observation, run the Visit Planner Tool. First, click an observation in the tree editor. Then, click the Visit Planner button in the top tool bar, which changes the view in the active GUI window. Next, 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
See also: APT Smart Accounting
To minimize excessive overheads, run Smart Accounting from the Visit Planner page by clicking the Run Smart Accounting button at the bottom right of the page. This updated the Charged Time field in the Proposal Information form—the charged time for the observing program, including exposure time and overheads, is now accurately calculated.