Chapter 26
WFPC2 Calibration

This chapter discusses the calibration of WFPC2 data, namely the routine processing that is required before detailed data analysis is performed. We begin by describing the pipeline calibration that occurs before the data are delivered to the original observer and stored in the Hubble Data Archive. We then detail possible reasons to repeat this routine calibration and the options available to do so. Finally, we mention a few additional steps that can be taken to enhance and complement the routine pipeline processing.

After WFPC2 observations have executed, the image data pass through the OPUS pipeline, where they are processed and calibrated. All of the steps performed by the pipeline are recorded in the trailer file for each dataset. Figure 26.1 shows an example of a trailer file and identifies comments made during the following pipeline steps:

1. The data are partitioned (separated into individual files, e.g., the engineering and science data are separated).
2. The data are edited to insert fill (an arbitrary assigned value given in the header) in place of missing data.
3. The data are evaluated to determine discrepancies between the subset of the planned and executed observational parameters.
4. The data are converted to a generic format and the header keywords -populated.
5. The data are calibrated using a standard WFPC2-specific calibration -algorithm and the best available calibration files.

CECCCM-******************************************* OBSERVER COMMENTS FILE *****************************************************

CECCBN-*************************************************************************************************************************

     OSS quality/utility report - Wide Field/Planetary Camera II (WFII)

     Observation:    Object name:        Proposal ID:    Executed (UT):

     U28S0303        PSR1957+20          05390           94.242/ 21:57:17

                            Observation Specifics

                            ---------------------

              Science Data Mode:                  IMAGE

              CCDs Used:                          ALL

              Data Format:                        STDMODE

              Pointing Control:                   FINELOK

              Filter(s):                          F675W

              Analog gain:                        7.5 electrons/DN

              Exp. time (sec):                     600

 Comments: This observation appears to have executed as planned.

 OSS staff did not inspect the observation.

   No terminator crossings occurred during this observation.

 OSS_INFO1:   OK - no apparent problems

 OSS_INFO2:   NO-MON - obs not monitored (lack of eng data and/or OSS staffing)

DPPBAN-***************************************************** TRAILER FILE *****************************************************

DPPSTA--------------------------------------------- DATA PARTITIONING STARTED ---------------------------------------------

DPPSTR-DATA PARTITIONING STARTED: 31-AUG-94 16:15:55 .

DPPOBS-Observation Identification: Program Number 28S , Observation Set Number 03 , Observation Number 03

DPPCAT-Msg Artifacts Catalog: DCF Msg 7 contained data for Info Set File with Root Name of U28S0303P

DPPIST-Missing pkts processing is complete, processed 3200 science pkts, detected 0 as missing

DPVWM1-Weighted Quality Measure of 0 was calc for errors reported in Quality & Acctg Capsule entries for Info Set

DPPNPR- 3201 packets expected, 3201 packets received ( 1 SHPs, 0 UDLs, 0 Bad pkts) for Info Set U28S0303P

DPPEND-DATA PARTITIONING ENDED: 31-AUG-94 16:23:06 .

DPPFIN--------------------------------------------- DATA PARTITIONING COMPLETED -------------------------------------------

CPE0ST-------------------------------------------- DATA EDITING STARTED -----------------------------------------------------

CPESTR-DATA EDITING STARTED 31-AUG-94 16:23:20 FOR U28S0303P.

DPE4PC- 0 fill source packets were inserted by PODPS.

DPE4DC-In U28S0303P, 0 source packets were found that contain fill data inserted by the ST DCF.

DPERSC-CP34SE: ...and 0 packets were found to have segments without Reed Solomon corrections

CPEEND-DATA EDITING ENDED 31-AUG-94 16:23:20 FOR U28S0303P.

CPE0EN--------------------------------------------- DATA EDITING COMPLETED -----------------------------------------------------

CPG0VS--------------------------------------------- DATA EVALUATION STARTED -----------------------------------------------

DPVSTR-DATA EVALUATION STARTED 31-AUG-94 16:23:39 FOR U28S0303P.

DPVEND-DATA EVALUATION ENDED 31-AUG-94 16:24:03 FOR U28S0303P.

DPVWM2-Weighted Quality Measure of 0 was calc for discrepancies between predicted & actual Flags & Indicators for Info Set

DPVOKK-Info Set quality was OK as Weighted Quality Measure of 0 did not exceed Quality Threshold of 9

CPG0VE--------------------------------------------- DATA EVALUATION COMPLETED ---------------------------------------------

CGAI00-

CGAI01---------------------------------WIDE FIELD AND PLANETARY CAMERA GENERIC CONVERSION BEGINNING-----------------------------

CGAI00-

CGAT01-Routine CGWFP2, version 34.4.A , will perform generic conversion

CGAT02-GENERIC CONVERSION BEGINNING: processing information set U28S0303P

CGAT03-CGWFP2 START: 31-AUG-94, 16:24:04

CGAW06-No error values detected in flags and indicators

CGAI06-SHP generic conversion has completed successfully

CGAC02-Generated new WFII reference file catalog : CCC:[SIS.WF2]U28S0303P.CTX

CGAI08-SCI generic conversion has completed successfully

CGAI22-DQM generic conversion has completed successfully

CGAT04-GENERIC CONVERSION TERMINATING: successful completion

CGAT09-CGWFP2 END: 31-AUG-94, 16:27:45

CPG0EN--------------------------------------------- GENERIC CONVERSION COMPLETED -----------------------------------------------

CCAI00-

CCAI07-CALIBRATION BEGINNING: processing information set 31-AUG-94

CGAI00-

CCAI07-CALIBRATION BEGINNING: processing information set U28S0303P

CCAI11-CCWFP2 START: 31-AUG-94, 16:33:17

CCAIRI- --- WF/PC-2 Calibration Starting: CALWP2 Version 1.3.0.6

CCAIRI- --- Starting CALWP2: Input = U28S0303P Output = ucal:u28s0303p

CCAIRI- --- Starting processing of element 1

CCAIRI- photmode = WFPC2,1,A2D7,F675W,,CAL

CCAIRI- --- Starting processing of element 2

CCAIRI- photmode = WFPC2,2,A2D7,F675W,,CAL

CCAIRI- --- Starting processing of element 3

CCAIRI- photmode = WFPC2,3,A2D7,F675W,,CAL

CCAIRI- --- Starting processing of element 4

CCAIRI- photmode = WFPC2,4,A2D7,F675W,,CAL

CCAIRI- --- Computing image statistics of element 1

CCAIRI- --- Computing image statistics of element 2

CCAIRI- --- Computing image statistics of element 3

CCAIRI- --- Computing image statistics of element 4

CCAIRI- --- WF/PC-2 Calibration Ending for observation

CCAI10-CALIBRATION END: 31-AUG-94, 16:38:30