TSR 2012-03: NPOL Reference File¶
Abstract: Authors: Nadezhda Dencheva, Warren Hack Date: 12 Oct 2010
The HST pipeline originally used two types of reference files to correct for distortion:
IDCTABfiles which contain the coefficients for a polynomial correction and
DGEOfiles which are images with the residual distortion. A new format for the residual distortion, called
_npl.fits), is presented in this document. The conversion from
NPOLfiles is described and an example of the format is given using ACS/WFC F606W filter. Tests of the conversion procedure show that the differences between the
NPOLfiles are of the order of pixels.