COS Reference File Tables

Reference files used by the COS calibration pipeline (CALCOS)) are updated on a regular basis. Current reference files files can be retrieved from the HST archive, or downloaded directly from the lref directory.

Flat Fields
The flat field image is a pixel-to-pixel flat; the large scale fluctuations in sensitivity will be accounted for in the photometric correction table.

Geometric Distortion Correction Images
The geometric distortion reference file is used to correct for the intrinsic nonlinearity (INL) of the FUV detector.

Bad Time Intervals Tables
The bad time intervals table gives start and stop times that indicate when there was an unusual level of interference or noise. TIME-TAG events during these intervals may not be due to actual photon events.

Baseline Reference Frame Tables
The baseline reference frame table gives the actual location of each of the two electronic stims, for each FUV segment. The table also contains parameters for the size of the region to be searched in an image for the stims.

Burst Parameters Tables
The burst parameters table is used for deciding when the count rate in some time interval in FUV time-tag data is too high to be regarded as normal, i.e. it is a burst.

1-D Extraction Parameters Tables
These tables give the location of the spectrum to be extracted from a 2-D image.

Data Quality Initialization Tables
The data quality initialization table gives the locations of rectangular regions that cover portions of the detector that are known to be less then optimal.

Deadtime Reference Tables
The deadtime reference frame table gives the livetime factor for various values of the observed global count rate.

COS Dispersion Relation Tables
The dispersion relation table gives a set of polynomial coefficients for computing wavelength from pixel number.

COS Template Cal Lamp Spectra Tables
The template cal lamp spectra table contains template wavecal spectra, to be compared with observed wavecal spectra.

COS Pulse Height Parameters Tables
The pulse height parameters reference table gives thresholds for checking FUV data based on pulse height.

COS Photometric Sensitivity Reference Tables
The photometric sensitivity reference table gives the instrumental sensitivity at each element of a 1-D extracted spectrum.

COS Time Dependent Sensitivity Tables
The time dependent sensitivity table gives information about the relative sensitivity as a function of time and wavelength. The relative sensitivity is represented by a piecewise linear function, one which is linear over intervals of time. The sensitivity may be discontinuous at an endpoint of a time interval. A separate function of time may be specified at each of a number of different wavelengths.

COS Wavecal Parameters Reference Table
The wavecal parameters reference table gives parameters which are relevant to wavecal processing.