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DrizzlePac: News

Reprocessing WFC3/UVIS and ACS/WFC images requires DrizzlePac v1.1.10

As of September 10, 2013, MAST calibrated data products for WFC3/UVIS contain additional header extensions describing the image distortion. OTFR calls an updated version of the DrizzlePac software (v1.1.10) to interpret the new D2IMFILE reference file containing these corrections, and it appends additional extensions of type 'D2IMARR' (four for WFC3/UVIS and two for ACS/WFC) to the flt.fits and flc.fits data products.

Users who obtained drizzled data after September 10, 2013, and wish to manually reprocess with AstroDrizzle will need to obtain a development version of the software (from May 6, 2013 or later) available via IRAFX to correctly interpret and apply the D2IMFILE corrections.

Please note that the latest public release of STSDAS or stsci_python contains DrizzlePac v 1.1.8 which will cause the software to crash with the new archival data products.

The new WFC3/UVIS distortion correction accounts for shifts induced by the lithographic-mask pattern imprinted on the detector during the manufacturing process (see STAN Issue 14 for details). The format of the new D2IMFILE is shown below, with 4 extensions corresponding to the two chips and two dimensions. Calibrated data (both raw.fits and flt.fits) contains an additional keyword (D2IMFILE) which points to this reference file, and four new extensions of type 'D2IMARR' are appended to the flt.fits images, as shown below in red.

--> catfits x5o1555ji_d2i.fits
EXT  FITSNAME      FILENAME  EXTVER DIMENS     BITPIX
0    x5o1555ji_d2i x5o1555ji_d2i                16        
1    IMAGE         DX           2   32x17      -32                                     
2    IMAGE         DY           2   32x17      -32                                     
3    IMAGE         DX           1   32x17      -32                                     
4    IMAGE         DY           1   32x17      -32

--> catfits icdm60ipq_flt.fits
EXT  FITSNAME      FILENAME  EXTVER DIMENS      BITPIX
0    icdm60ipq_flt icdm60ipq_flt                16              
1    IMAGE         SCI          1   4096x2051  -32                             
2    IMAGE         ERR          1   4096x2051  -32           
3    IMAGE         DQ           1   4096x2051   16            
4    IMAGE         SCI          2   4096x2051  -32            
5    IMAGE         ERR          2   4096x2051  -32           
6    IMAGE         DQ           2   4096x2051   16            
7    IMAGE         D2IMARR      1   32x17      -32           
8    IMAGE         D2IMARR      2   32x17      -32                                
9    IMAGE         D2IMARR      3   32x17      -32                                
10   IMAGE         D2IMARR      4   32x17      -32            
11   BINTABLE      WCSCORR      1   24Fx14R                  

For ACS/WFC, the D2IMFILE provides a 1D array of column width corrections, and the distortion solution itself has not changed. However, in order to be compatible with the updated DrizzlePac software (which expects a separate solution for each chip, as required by the new WFC3/UVIS correction), the format of the ACS D2IMFILE has changed, as shown below. In the new reference file, the 1D correction for chip 1 has simply been copied to chip 2. As a result, calibrated data (both flt.fits and flc.fits) now contains one additional extension of type 'D2IMARR' appended to each file, as shown below in red. Because of this change in the number of extensions in calibrated data products, the updated version of DrizzlePac is required to reprocess these files.

--> catfits v971826mj_d2i.fits
EXT  FITSNAME      FILENAME  EXTVER DIMENS      BITPIX
0    v971826mj_d2i v971826mj_d2i                16                            
1    IMAGE         DX           1   4096       -32                                  
       
--> catfits v971826mj_d2i.fits
EXT  FITSNAME      FILENAME  EXTVER DIMENS      BITPIX
0    x5u17177j_d2i x5u17177j_d2i                16                               
1    IMAGE         DX           1   4096x1     -32                                       
2    IMAGE         DX           2   4096x1     -32                                       

--> catfits jb5g01haq_flc.fits
EXT  FITSNAME      FILENAME  EXTVER DIMENS      BITPIX
0    jb5g01haq_flc jb5g01haq_flc                16                                      
1    IMAGE         SCI          1   4096x2048  -32                                         
2    IMAGE         ERR          1   4096x2048  -32                                       
3    IMAGE         DQ           1   4096x2048   16                                        
4    IMAGE         SCI          2   4096x2048  -32                                         
5    IMAGE         ERR          2   4096x2048  -32                                       
6    IMAGE         DQ           2   4096x2048   16                                        
7    IMAGE         D2IMARR      1   4096x1     -32                                   
8    IMAGE         D2IMARR      2   4096x1     -32                            
9    IMAGE         WCSDVARR     1   65x33      -32                                  
10   IMAGE         WCSDVARR     2   65x33      -32                                 
11   IMAGE         WCSDVARR     3   65x33      -32                                 
12   IMAGE         WCSDVARR     4   65x33      -32                                 
13   BINTABLE      WCSCORR      1   24Fx14R