Reference File

The reset correction step uses a RESET reference file.

CRDS Selection Criteria

Reset reference files are selected on the basis of INSTRUME, DETECTOR, READPATT and SUBARRAY values for the input science data set.

RESET Reference File Format

The reset reference files are FITS files with 3 IMAGE extensions and 1 BINTABLE extension. The FITS primary data array is assumed to be empty. The characteristics of the three image extension are as follows:

EXTNAME NAXIS Dimensions Data type
SCI 4 ncols x nrows x ngroups x nint float
ERR 4 ncols x nrows x ngroups x nint float
DQ 2 ncols x nrows integer

The BINTABLE extension contains the bit assignments used in the DQ array. It uses EXTNAME=DQ_DEF and contains 4 columns:

  • BIT: integer value giving the bit number, starting at zero
  • VALUE: the equivalent base-10 integer value of BIT
  • NAME: the string mnemonic name of the data quality condition
  • DESCRIPTION: a string description of the condition

The SCI and ERR data arrays are 4-D, with dimensions of ncols x nrows x ngroups X nints, where ncols x nrows matches the dimensions of the raw detector readout mode for which the reset applies. The reference file contains the number of NGroups planes required for the correction to be zero on the last plane Ngroups plane. The correction for the first few integrations varies and eventually settles down to a constant correction independent of integration number.