Reducing Science Data

If chopping was not used, then the most basic way of taking IR spectra is to observe the target along two slit positions. The sky is then removed by a process which is sometimes called double sky subtraction. The basic steps of how to reduce these type of data are:

• Dark subtraction
• Ghost removal *
• Non-linearity correction *
• Flat Fielding
• First sky subtraction
• Distortion Correction and wavelength calibration
• Registration and stacking
• Extraction
• Telluric line correction
• Flux calibration

For frames taken with chopping, the basic steps are:

• Ghost removal *
• Non-linearity correction *
• Flat Fielding
• A-B Subtraction
• Slit Curvature Correction and wavelength calibration
• Registration and stacking
• Extraction
• Telluric line correction
• Flux calibration

Steps that are marked with an asterisk have not been thoroughly tested.