NIRSpec Multi-Object Spectroscopy APT Template
NIRSpec's multi-object spectroscopy (MOS) observing mode provides the means to simultaneously obtain the spectra of multiple objects within its 3.4 × 3.6 arcmin overall field of view. Because of the complexity of this mode, the MSA Planning Tool (MPT) within APT was developed to help users create MOS observations.
Caution: MOS observations are created differently!
The MOS APT Template should not normally be filled out by the user. Instead, the MSA Planning Tool (MPT) should be used.
On this page
Introduction: Start preparing your MOS observation with the MSA Planning Tool
For most MOS science, users should not begin by filing out the MOS APT template. Start with the MSA Planning Tool (MPT) instead. MPT will automatically populate the template when an observation is created. Follow the instructions in the MSA Planning Tool, MPT page.
Words in bold are GUI menus/
panels or data software packages;
bold italics are buttons in GUI
tools or package parameters.
When an observation is defined using the MPT, the user should then complete a few remaining fields in the observation template:
- The exposure parameters should be specified,
- any (optional) confirmation images can be added, and
- any observation special requirements, especially those required for MOS observations described in the JWST Multi-Object Spectroscopy Roadmap.
MOS APT template parameters
The NIRSpec multi-object spectroscopy template parameters are listed in Table 1.
Table 1. NIRSpec MOS APT template parameters
Field | Details | Values | Notes |
---|---|---|---|
General observation information | |||
Observation Number | Assign an observation number | Number | During program implementation, the observation number should not be changed. |
Observation Label | Provide an observation label | Text | Optional |
NIRSPEC | |||
Observation Template | NIRSpec Multi-Object Spectroscopy | ||
Coordinated Parallel | Checkbox | Choose NIRCam or MIRI imaging from pull-down list | Check the box if adding NIRCam or MIRI parallels, then select from the pull-down menu |
Target | Select a target name from the Targets folder | Can be a Moving Target, Fixed Target, or an MSA Catalog Target | |
Special Requirements | Specify special requirements | Choose from list | If needed |
Observation Comments | Provide observation comments | Text | Optional |
Target acquisition parameters | |||
TA Method | Select TA method from pull-down list | NONE, MSATA, WATA, VERIFY_ONLY | MSATA is required for an MSA Catalog Target WATA is the default for moving target or long slit observation of extended fixed target |
MSATA visit-level selections | |||
Reference Star Bin | List of reference stars and MSA configuration | Choose from list | Bins of candidate reference stars are constructed for each TA filter and readout pattern when MSATA is used. The user must select one bin. This is typically done for the program update (after an Aperture PA is assigned by StScI). |
Filter name | Will be determined from the user-selected reference star bin | ||
Readout pattern | Will be determined from the user-selected reference star bin | ||
Select MSA configuration | Choose Auto Acq MSA Config or ALLOPEN | Default is an auto-generated protective MSA configuration for selected reference star bin | |
WATA target acquisition exposure | |||
Acq Target | Select acquisition target | Choose from list | |
Acq Subarray | Select subarray | SUB32, SUB2048, FULL | |
Acq Filter | Select filter | F110W, F140X, or CLEAR | |
Acq Readout Pattern | Select readout pattern | NRSRAPID, NRSRAPIDD6 | |
Specify ETC Workbook Calculation ID | Number | Optional ETC workbook ID | |
Pointing verification (PV) image | |||
Select filter name | Choose from list F110W, F140X, or CLEAR | PV images are offered when TA Method = VERIFY_ONLY. These images are taken at the end of each visit. | |
Select readout pattern | Choose one: NRS, NRSRAPID, NRSIRS2, NRSIRS2RAPID | ||
Specify number of groups/integration | Number | ||
PV MSA Configuration | Specify filename or value | Choose from list that includes ALLOPEN, ALLCLOSED, Q4 Field Point 1 Long Slit, Q4 Field Point 2 Long Slit | |
Science parameters | |||
Primary Candidate List | Select from available candidate sets defined in the MSA Catalog Target | MPT will populate this | |
Filler Candidate List | Select from available candidate sets defined in the MSA Catalog Target | MPT will populate this | |
Aperture PA | Planned and Assigned angle fields are shown. Assigned is blank until an angle is assigned by STScI. | Values from 0 to 360 degrees | Planned aperture position angle is the angle used to run MPT, and is greyed out in the template. Assigned is the Aperture position angle given to the observation for making flight updates. |
Dither Type (if Coordinated Parallels checkbox is enabled and NIRSpec MOS-NIRCam imaging is selected.) | Select option for dithers | NONE 2-POINT-WITH-NIRCAM-SIZE1 2-POINT-WITH-NIRCAM-SIZE2 2-POINT-WITH-NIRCAM-SIZE3 3-POINT-WITH-NIRCAM-SIZE1 3-POINT-WITH-NIRCAM-SIZE2 3-POINT-WITH-NIRCAM-SIZE2 | This option is only available when NIRCam imaging coordinated parallels are included. Additional small dithers in the cross-dispersion direction improve PSF sampling in the NIRCam imaging. |
Science Aperture | Select aperture | MSA_Center, Q4 Field Point 1, Q4 Field Point 2 | Select MSA_Center for MOS observations planned with MPT. Other selection options are for use with the pre-defined MSA long slit configurations. |
Science exposure specification table | |||
Grating/Filter | Select grating/filter name | Choose from list | Select one grating/filter pair per exposure line |
Readout Pattern | Select readout pattern | NRS, NRSRAPID, NRSIRS2, NRSIRS2RAPID | Select from one of the traditional or IRS2 readout modes. |
Groups/Int | Specify number of groups per integration | Number | |
Integrations/Exp | Specify number of integrations per exposure | Number | |
Autocal | Select auto calibration option | Choose from NONE, WAVCAL, FLAT, BOTH | NONE is recommended |
Specify ETC Workbook Calculation ID | Number | Optional | |
Science configurations/pointings table | |||
MSA Configuration | Select MSA configuration | Choose from list | Can be a custom MSA configuration, one created using the MSA Planning Tool, or a pre-defined long slit. |
Exposure Specification | Select Grating/Filter combination | Choose from list of grating/filter specification in the Exposure Specification table | Indicates the line from the Exposure Specification table that is used for a row in the Configurations/Pointings table. If generated from an MPT Plan, these will be filled in. |
Pointing | RA and Dec of the Pointing | Defaults to MSA Catalog Target Reference point if not specified | The base pointing; if the observation was generated from an MPT Plan, this is the pointing of the exposure. |
Dispersion Offset | Number in (fractional) shutters | Offset from base pointing in dispersion direction (X) | |
Cross-Dispersion Offset | Number in (fractional) shutters | Offset from base pointing in spatial, or cross-dispersion, direction (Y) | |
Nod Pattern | Choose from list when building MOS observation manually 2 shutter slitlet, 3 shutter slitlet, 5 shutter slitlet, 5 shutter slitlet with gaps | Can be specified directly in the template, or selected by MPT. If generated from an MPT Plan, this is automatically populated. | |
Total Integrations | Number | Value depends on the number of nods selected | |
Total Exposure Time | Number of seconds | Exposure duration for all integrations in the exposure specification | |
Edit Config | click "Edit" button | Click button to edit configuration | Option to alter the MSA configuration of one or more exposures. Clicking this will bring up the MSA configuration editor. |
Confirmation images | |||
Obtain Confirmation Images | Specify if confirmation images are desired | Choose After Target Acq or After Target Acq and New MSA Config | Option to obtain confirmation images of the science sources in the science slits with the science dispersers. (Selecting After Target Acq will not work for TA Method = VERIFY_ONLY or NONE) |
Confirmation Type | Reflects the selection of Obtain Confirmation Images parameter | ||
Conf. Readout Pattern | Select readout pattern | NRS, NRSRAPID, NRSIRS2, NRSIRS2RAPID | Readout pattern choices will be a subset depending on the science mode (traditional or IRS2). |
Confirmation Groups/Int | Specify number of groups per integration | number |
References
Karakla, D. et al. 2014, Proc. SPIE 9149
The NIRSpec MSA Planning Tool for multi-object spectroscopy with JWST