15.2 How Phase II Parameter Choices Affect Calibration

Table 15.1: Calibration Dependencies on Phase II Parameter Choices.


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.


Not calibrated; receive raw data files only.


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
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.


Normal calibration processing.


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


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.


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.