This module provides comprehensive functions for calculating the instrument's efficiency and response curves, and for flux calibrating IFU spectra and data cubes.

Key functionalities include:

• Computing instrument efficiency from standard star observations
• Calculating system response curves (observed vs. reference star spectra)
• Telluric absorption correction using atmospheric models
• Atmospheric extinction corrections based on airmass
• Response curve smoothing using running median filters
• Polynomial fitting with kappa-sigma clipping for response curves
• Wavelength window selection for response fitting and quality assessment
• Flux calibration of both 1D spectra and 3D data cubes
• Support for multiple observing bands (J, H, K, H+K) with various resolutions
• Quality control parameter calculation and logging

The module handles both ERIS and SINFONI data formats with appropriate gain corrections. It uses HDRL (High-level Data Reduction Library) for spectral operations and GSL (GNU Scientific Library) for polynomial fitting.

Typical workflow:

1. Extract spectrum from standard star observation
2. Compute response using eris_response_compute()
3. Optionally compute efficiency using eris_efficiency_compute()
4. Apply flux calibration to science spectra/cubes

Note

All wavelength units are in micrometers (um) unless otherwise specified

Gain correction accounts for detector conversion from ADU to electrons

Response curve quality depends on atmospheric conditions and standard star selection