STScI Calibration Data System

ACS nplfile

Files which, along with D2IMFILE, replace DGEOFILE with 65x33 table of non-polynomial corrections for X and Y for each chip.

The NPOLFILE contains tabular information about residual distortion corrections for some instrument modes. It's an optional correction and is only added to the FITS file and used in coordinate transformations if the filename is specified in the header. When used with CALACS, these files create image extensions (WCSDVARR) in the calibrated data which contain the non-polynomial distortion corrections. MultiDrizzle uses the DGEOFILE reference files for applying non-polynomial distortion corrections. There are two full-chip size image extensions in the DGEOFILE reference file for each instrument detector chip; one extension contains residuals of the polynomial fit in x, and the other contains residuals of the polynomial fit in y.

As outlined in Anderson, 2002, residuals of the polynomial fit were originally modeled by sampling every 64 pixels in the WFC, creating a 65 x 33 table for each chip. For the HRC, it was every 16 pixels sampled and modeled to create a 65 x 65 table. The value of a residual distortion at any point on the chip is determined by interpolation. These tables were used to create a full-chip distortion image, the DGEOFILE reference image, for each camera.

Because of the coordinate transformations, and the many steps involved in creating DGEOFILE files, it was not possible to start with the original tables. Therefore, the NPOLFILES were created for use by AstroDrizzle, done by subtracting the column-width corrections from the DGEOFILE file, then sampling each full chip size DGEOFILE file extension to re-create the look-up tables. Tests have shown a near 1-to-1 match with the original images.

To retrieve a file from the archive, click in the file name. For details on how to correctly set up the Archive retrieval options for reference files, check our Help page.

To receive e-mail notifications of deliveries of new reference files, you can subscribe to instrument specific mailing lists. More.

See the reference file delivery logsheet for more information. These files can also be downloaded directly from the jref directory. If you choose to access the files via this ftp server, keep in mind that there is a known bug in trying to access files via ftp server using Safari. The recommended browser is Firefox.

File Detector Use After Pedigree Delivery # Delivery Date OTFR Start Use Date Comments
xc215013j_npl.fits SBC Mar 01 2002 00:00:00 UT INFLIGHT 12649 Dec 02 2013 15:01:37 GMT Dec 02 2013 15:52:21 GMT Residual geometric distortion file for us
v971826lj_npl.fits SBC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826kj_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826jj_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826ij_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826hj_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826gj_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826fj_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826ej_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826dj_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826cj_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826bj_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971826aj_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718269j_npl.fits WFC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718268j_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718267j_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718266j_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718265j_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718264j_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718263j_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718262j_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718261j_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v9718260j_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us
v971825tj_npl.fits HRC Mar 01 2002 00:00:00 UT INFLIGHT 12456 May 29 2012 16:08:48 GMT May 29 2012 17:27:27 GMT Residual geometric distortion file for us