Obtaining science data from COS: the calibration process

COS has two distinct ultraviolet channels covering the spectral range from 1150a to 3200a. The NUV channel covers the range from 1700a to 3200a and uses the Hubble Space Telescope's STIS spare MAMA. The FUV channel uses a micro channel plate detector with a cross-delay line readout system to cover the range from 1150a to 1900a. Due to the analog nature of the readout electronics of the FUV detector, this system is sensitive to temperature variations and has non-uniform pixel size across its sensitive area. We present a step-by-step description of the calibration process required to transform raw data from the COS into fully corrected and calibrated spectra ready for scientific analysis. Initial simulated raw COS data is used to demonstrate the calibration process.