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Hubble Space Telescope
WFPC2 Reference Files Currently in the Calibration Database

by Sylvia Baggett and Michael S. Wiggs

Table of Contents

1: Introduction
2: Decontaminations
3: Mask Files
4: A to D Files
5: Bias Files
6: Dark Files
7: Flatfield Files
8: Shutter Shading Files
9: IDT Delta Dark Files
10: Pixel Area Correction
11: Geometric Distortion
12: Advisories about Particular Files and Observing Modes

NOTE TO USERS: If, on occasion, this list has not been updated, users can still find the most recent reference files via:


1: Introduction

This document contains a listing of all WFPC2 reference files, grouped by type, that are presently available in the Calibration Database (CDB) System. These tables are intended to inform observers as to the quality of the calibration applied to their data by the PODPS pipeline processing and to provide an aid in selecting appropriate reference files for the re-calibration of WFPC2 observations. These datafiles may be requested by name from the STScI in the same fashion as any other non-proprietary data products.

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 correction flatfields**

** Note: the "correction" flatfields (.r6h/.r6d) are based on the Cycle 4 flats, and have improved noise levels compared to standard pipeline flatfields, particularly in the UV. The correction flats are available for application to existing calibrated data; they are NOT currently in use in the pipeline but must be applied manually to appropriately pipeline-calibrated files. Note also that these flats are based solely upon the Cycle 4 flats and do not take into account changes in the flatfields or camera optics since that time. Please refer to ISR 01-07 for details on these special correction flats and their use. Since they are not standard pipeline flatfields, they have a non-standard r6h/r6d extension and do not have a useafter date.

In the table below, the source of each reference file is specified in the "S" column: ground test data (G), or in-flight (I). The ground test data were obtained during the Thermal Vac test performed on the instrument prior to launch, while the in-flight reference files are those obtained on-orbit. For the flatfields, an additional column, labeled NM, indicates the number of earth-calibs (observations of the bright Earth) or internal flatfields used to create each flatfield. Finally, any other pertinent comments concerning a particular reference file are delegated to the last column.

Many WFPC2 reference files are available via anonymous FTP at the following URLs; if the flats are not online, they must be retrieved from the Archive or from STARVIEW.

ftp://ftp.stsci.edu/cdbs/cdbs8/uref/  -- FTP site: most current reffiles.

2: The WFPC2 Decontaminations

The link below provides a list of decontamination dates:

Dates of Decontamination Procedures.


3: Mask Files

CDBS list of WFPC2 Mask Files.

4: A to D Files

CDBS list of WFPC2 A to D Files.

5: Bias Files

CDBS list of WFPC2 Bias Files.

6: Dark Files

CDBS index of WFPC2 Dark Files.


7: Flatfield Files

Note: new updated flatfields have been created for all 32 of the WFPC2 standard optical filters (narrow-band, medium-band, broad-band and long-pass filters redwards of F300W), with USEAFTER dates of 1995-09-01 and 1996-10-30. These are automatically applied in the pipeline to data from the appropriate time periods; please refer to WFPC2 ISR 2002-02 for further details about these flats and how they were created.

In addition, a set of averaged flatfields based on the Cycle 4 reference flats are available, that can be applied to UV filters or other data from before 1995-09-01. Note that these flatfields are NOT currently in use in the pipeline but must be applied manually to appropriately pipeline-calibrated files, after the data have been retrieved from the archive. Please refer to ISR 01-07 for details on these special correction flats and their use. Since they are not standard pipeline flatfields, they have a non-standard r6h/r6d extension and do not have a useafter date.

CDBS list of WFPC2 Flat Field Files

9: IDT's DeltaDarks (File extension r6h/b6h)

Warning: these files will require clipping before use; please read IDT memo (wfpc2_idtrefs.memo) for details on how to modify and use these files!

USEAFTER  MODE CLK  GAIN DATA_FILE  COMMENT

19940101  full off    7  ecg1136au    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940102  full off    7  ecg1136du    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940117  full off    7  ecg1136fu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940201  full off    7  ecg1136lu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940201  full off    7  ecg1136ou    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940218  full off    7  ecg1136ru    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940219  full off    7  ecg1136tu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940221  full off    7  ecg11372u    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940223  full off    7  ecg11374u    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940303  full off    7  ecg11377u    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940308  full off    7  ecg11379u    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940314  full off    7  ecg1137du    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940321  full off    7  ecg1137fu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940328  full off    7  ecg1137iu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940404  full off    7  ecg1137lu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940415  full off    7  ecg1137nu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940418  full off    7  ecg1137qu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940424  full off    7  eck1344tu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940502  full off    7  eck13452u    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940509  full off    7  eck13457u    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940516  full off    7  eck1345au    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940523  full off    7  eck1345cu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940530  full off    7  eck1345fu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940606  full off    7  eck1345hu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940613  full off    7  ecl0919cu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940620  full off    7  ecl0919eu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940627  full off    7  ecl0919gu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940704  full off    7  ecl0919ju    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940718  full off    7  ecl0919lu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940725  full off    7  ecl0919nu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940802  full off    7  ecm0904du    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940809  full off    7  ecm0904fu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940816  full off    7  ecm0904hu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940823  full off    7  ecm0904ju    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940830  full off    7  ecm0904mu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940906  full off    7  ecm0904ou    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940915  full off    7  ecm0904qu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940920  full off    7  ecm0945eu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19940930  full off    7  ecm0945hu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19941003  full off    7  ecm0945ku    IDT deltadark; see wfpc2_idtrefs.memo before using!
19941011  full off    7  ecm0945mu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19941017  full off    7  ecm0945pu    IDT deltadark; see wfpc2_idtrefs.memo before using!
19941025  full off    7  ecm0945ru    IDT deltadark; see wfpc2_idtrefs.memo before using!
19941101  full off    7  ecm09460u    IDT deltadark; see wfpc2_idtrefs.memo before using!

10. Pixel Area Correction

Finally, when performing integrated photometry, users should be aware that WFPC2 has significant distortion which causes the pixel area to vary across the field. The application of flat-fields "corrects" for this and normalizes all pixels to have the same area. However, this renders integrated photometry incorrect, because all of the light falls on the distorted pixels and correcting for the pixel area changes the amount of total light.

Consequently if you are measuring integrated brightnesses (as opposed to surface brightnesses), you will want to put back the true relative pixel areas. Maps of these can be found in the distort flats directory. Multiply by these maps to put the relative areas back into the image. The maps are normalized to unity at (400,400) in each chip.

This file is available at:

http://www.stsci.edu/instruments/wfpc2/Wfpc2_phot/

Or available from the HST Archive:

filename: f1k1552bu, extension is r9h/r9d

when requesting from Starview, go into "Searches", select "DataFiles", then "Dataset Name" screen and enter your desired file name (without extension) in the "dataset name" field.

Or available via anonymous ftp in:

ftp://ftp.stsci.edu/cdbs/uref/


11: Geometric Distortion:

The WFPC2 Geometric Distortion correction files (f1k1552bu.r9h (text), f1k1552bu.r9d (binary)) can be found in the WFPC2 Photometry directory.


12: Advisories about Particular Files and Observing Modes:

Area Modes

As of April 2008, there are 303 WFPC2 area mode images in the archive, out of >100000 external images; due to this limited usage, area mode is not supported at the same level as full mode. Although an effort is made to have the best files in place at the time the area mode images are taken (area mode reference files are based on their full mode counterparts), reference files for area mode images are generally NOT updated when later improvements are made to full mode reference files. Researchers are advised to consult the list of best reference files available above and to consider generating their own area mode versions from any new full mode files in order to recalibrate archival images. For assistance, questions, or problems, e-mail: help@stsci.edu.

F160BW, PC only

Due to the noise in the true F160BW flatfield (i5515214u and e4510337u), the F255W flatfield (i5515218u) may be substituted. Note that the vignetting in the WF chips in F160BW limits this workaround to PC only. This workaround is not implemented in the pipeline; the alternate flatfield must be manually edited into the headers and the data recalibrated via calwp2.

Alternatively, one of the new new "correction" flatfields (.r6h/.r6d), with reduced noise levels, may be used. Note that they are NOT currently in use in the pipeline but must be applied manually to appropriately pipeline-calibrated files. Please refer to ISR 01-07 for details on these special correction flats and their use. Since they are not standard pipeline flatfields, they have a non-standard r6h/r6d extension and do not have a useafter date.