spectral_efficiency
===================

SpectralEfficiency
++++++++++++++++++


Applies the grating efficiency (blaze function) for a SpectralTraceList.

Input Data Format
-----------------
The efficiency curves are taken from a fits file `filename`with a
structure similar to the trace definition file (see `SpectralTraceList`).
The required extensions are:
- 0 : PrimaryHDU [header]
- 1 : BinTableHDU or TableHDU[header, data] : Overview table of all traces
- 2..N : BinTableHDU or TableHDU : Efficiency curves, one per trace. The
         tables must have the two columns `wavelength` and `efficiency`

Note that there must be one extension for each trace defined in the
`SpectralTraceList`. Extensions for other traces are ignored.

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 : (Bin)TableHDU : Overview of traces
++++++++++++++++++++++++++++++++++++++++++
No special header keywords are required in this extension.

Required Table columns:
- description : str : identifier for each trace
- extension_id : int : which extension is each trace in

EXT 2 : (Bin)TableHDU : Efficiencies for individual traces
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Required header keywords:
- EXTNAME : must be identical to the `description` in EXT 1

Required Table columns:
- wavelength : float : [um]
- efficiency : float : number [0..1]