15.2 How Phase II Parameter Choices Affect Calibration

Table 15.1: Calibration Dependencies on Phase II Parameter Choices.

Parameter

Effect in pipeline calibration

Engineering MODE

Not calibrated; receive raw data files only.

Available-but-unsupported MODE

Calibrated through flat fielding only; no 2-D rectification, cosmic ray rejection (if applicable), flux calibration, or 1-D extraction.

MODE=ACQ or ACQ/PEAK

Not calibrated; receive raw data files only.

MODE=TIME-TAG

Data events are tabulated in rootname_tag.fits file with one binary table extension for each buffer read (determined by exposure time and BUFFER-TIME parameters). All raw data events are gathered into a single image, rootname_raw.fitswhich is then passed through the normal calibration steps.

CCD only
CR-SPLIT > 1
or
Number_of_Iterations > 1

The number of imsets in the raw file equals CR-SPLIT or Number_of_Iterations. Raw file imsets are cosmic ray rejected and summed before the bias, dark, and flat-fielding corrections are made, producing a rootname_crj.fitsfile. The individual imsets are also flagged for cosmic rays and processed without summing to produce a rootname_flt.fits file.

MAMA only
Number_of_Iterations > 1

The raw file contains Number_of_Iterations imsets, as do the flat-fielded and 2-D rectified files; the 1-D extracted files contain Number_of_Iterations tables. Repeat exposure imsets are summed after flat-fielding and 2-D rectification producing files rootname_sfl.fits and rootname_x2d.fits respectively (this is also true for imaging data). Note that for the MAMA detectors, 1-D spectral extraction data are not summed even when there are repeat exposures.

POS-TARG

Normal calibration processing.

PATTERN

Separate PATTERN step exposures are not associated with each other. Each PATTERN step exposure is processed through calibration independently.

WAVECAL=NO

If GO wavecals (i.e., TARGET=WAVE exposures) are obtained at the same MSM position instead of autowavecals, full pipeline spectral calibration is performed. If no onboard wavecals are obtained, 1-D extraction and 2-D rectification of spectral data will not be done, because the associated wavelengths would be incorrect and therefore misleading.

Target_Name=CCDFLAT

An internal STIS CCD flat-field lamp exposure useful in post-pipeline processing to correct for fringing above ~7000 Å with gratings G750L and G750M.