spectral_trace_list

SpectralTraceList

List of spectral trace geometries for the detector plane.

Should work in concert with an ApertureList (or ApertureMask) object and a DetectorList object

Spectral trace patterns are to be kept in a fits.HDUList with one or more fits.BinTableHDU extensions, each one describing the geometry of a single trace. The first extension should be a BinTableHDU connecting the traces to the correct Aperture and ImagePlane objects.

The fits.HDUList objects can be loaded using one of these two keywords:

  • filename: for on disk FITS files, or

  • hdulist: for in-memory fits.HDUList objects

The format and contents of the extensions in the HDUList (FITS file) object is listed below

Input Data Format

A trace list FITS file needs the following extensions:

  • 0 : PrimaryHDU [header]

  • 1 : BinTableHDU [header, data] : Overview table of all traces

  • 2..N : BinTableHDU [header, data] : Trace tables. One per spectral trace

EXT 0 : PrimaryHDU

Required Header Keywords:

  • ECAT : int : Extension number of overview table. Normally 1

  • EDATA : int : Extension number of first Trace table. Normally 2

No data is required in this extension

EXT 1 : BinTableHDU : Overview of traces

No special header keywords are required in this extension

Required Table columns:

  • description : str : identifier of each trace

  • extension_id : int : which extension is each trace in

  • aperture_id : int : which aperture matches this trace (e.g. MOS / IFU)

  • image_plane_id : int : on which image plane is this trace projected

EXT 2 : BinTableHDU : Individual traces

Required header keywords: - EXTNAME : must be identical to the description in EXT 1

Recommended header keywords: - DISPDIR : “x” or “y” : dispersion axis. If not present, Scopesim tries

to determine this automatically; this may be unreliable in some cases.

Required Table columns: - wavelength : float : [um] : wavelength of monochromatic aperture image - s : float : [arcsec] : position along aperture perpendicular to trace - x : float : [mm] : x position of aperture image on focal plane - y : float : [mm] : y position of aperture image on focal plane

SpectralTraceListWheel

A Wheel-Effect object for selecting between multiple gratings/grisms.

See SpectralTraceList for the trace file format description.

Parameters

trace_list_nameslist

The list of unique identifiers in the trace filenames

filename_formatstr

f-string that directs scopesim to the folder containing the trace files. This can be a !-string if the trace names are shared with other *Wheel effect objects (e.g. a FilterWheel). See examples.

current_trace_liststr

default trace file to use

kwargskey-value pairs

Addition keywords that are passed to the SpectralTraceList objects See SpectralTraceList docstring

Examples

A simplified YAML file example taken from the OSIRIS instrument package:

alias: INST
name: OSIRIS_LSS

properties:
  decouple_detector_from_sky_headers: True
  grism_names:
    - R300B
    - R500B
    - R1000B
    - R2500V

effects:
  - name: spectral_trace_wheel
    description: grism wheel contining spectral trace geometries
    class: SpectralTraceListWheel
    kwargs:
      current_trace_list: "!OBS.grating_name"
      filename_format: "traces/LSS_{}_TRACE.fits"
      trace_list_names: "!INST.grism_names"

  - name: grating_efficiency
    description: OSIRIS grating efficiency curves, piggybacking on FilterWheel
    class: FilterWheel
    kwargs:
      minimum_throughput: !!float 0.
      filename_format: "gratings/{}.txt"
      current_filter: "!OBS.grating_name"
      filter_names: "!INST.grism_names"