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Calibration Reference Data System

Reference files used by the WFPC2 calibration pipeline (CALWP2) have been updated on a regular basis. All available reference files can be retrieved from the HST archive, or downloaded directly from the uref directory. Note that FTP access is browser dependent: Safari does not work; Firefox or Chrome may or may not work depending on the Operating System. If you cannot download the files via Firefox or Chrome, you can try using a standalone FTP tool or accessing the ftp site directly (ftp with 'anonymous' (without quotes) as your username and your email address as your password.

Each reference file has listed along with it the suggested "use after" date, the camera used and where necessary, the shutter, filter numbers, atodgain, clock, and/or filternames are given as well. The dataname in the table is the rootname of the reference file; the file extensions follow the convention outlined in ICD 47 (Post Observation Data Processing System to Calibration Data Base System Interface Control Document, Chapter 7):

 ASCII header   Binary data   type of reference file 
  ------------   -----------   ----------------------
    .r0h           .r0d        static mask
    .r1h           .r1d        analog to digital converter correction
                               lookup table

    .r2h           .r2d        bias frame
    .b2h           .b2d        bias data quality file

    .r3h           .r3d        dark frame
    .b3h           .b3d        dark data quality file

    .r4h           .r4d        flatfield 
    .b4h           .b4d        flatfield data quality file

    .r5h           .r5d        shutter shading correction

    .r6h           .r6d        (non-pipline) delta darks and correction flatfields
    .r7h           .r7d        WF4 anomaly correction
    .r9h           .r9d        pixel area correction file

New tools for exploring WFPC2 Reference Files are now available at https:/ To get a listing of the reference files you're interested in, click on 'wfpc2' then select the filetype. Use the names below in the Header Keyword column as a guide.

Pipeline Reference Files Extension Header Keyword Mode
Mask Tables
Flags defects in the CCD that degrade pixel performance but are stable over time. More...
A to D Tables
Corrects value of each pixel for the analog-to-digital conversion error. More...
Bias Images
Used to remove any position-dependent bias pattern remaining after the pedestal level is removed. More...
Dark Images
Used to detect CCD counts caused by thermal processes at the interfaces between the silicon and oxide layers, as well as charged particle and secondary radiation events. More...
Flatfield Images
Corrects for the large-scale illumination pattern and the pixel-to-pixel response function. More...
Shutter Shading Images
Corrects the effects of the shutter motion in short (<10 seconds) exposures. More...
WF4 Correction Tables
Used to correct low CCD bias levels and lowered count levels (low CCD gain) on the WF4 detector. More...
.r7h/d WF4TFILE N/A
Distortion Correction Table
Used in drizzling WFPC2 images. Contains the best distortion models for all four chips. More...
Inter-chip Offsets Table
Used in conjunction with the IDC table; contains the secular relative orientations and positions of the chips. More...
34 Row Displacement Correction File
Corrects for the reduced sensitivity seen in approximately every 34th row in the detectors. More...

Non-pipeline Reference Files Extension Header Keyword Mode
IDT Superbias Files
Early bias files created by the IDT to remove any position-dependent bias pattern remaining after the pedestal level is removed. More...
IDT Superdark Files
Early dark files created by the IDT; behave like regular pipeline darks, may have better noise characteristics. More...
IDT Deltadark Files
Used with IDT Superdark and Superbias files to remove hot pixels in early WFPC2 data. More...
Correction Flats from Erich Karkoschka
Correction flat to be multiplied by the 'previous' flatfield to produce a less noisy revised flatfield. More...
.r6h/d --- FULL
Pixel Area Correction File
Used to restore the proper total counts of the target. More...
.r9h/d --- FULL