SEPTEMBER 13, 2011

CALCOS v2.15.4 Release Notes

This version has been installed with STSDAS Version 3.14 Released on August 2011. This has not been installed in OPUS yet.

This describes changes from calcos version 2.13.6 to 2.15.4.

Relevant Trac tickets and PRs

Trac PR Updates
465 63864 Calcos should copy G140L wavecal info from A to B.
616 66158 Calcos should be modified to use Sphinx for documentation.
628 66626 Calcos should use images for pulse height limits.
635 66908 Calcos should write a 3-D csum file for any FUV TIME-TAG file.
639 67114 Change calcos procedure for adding WCSAXES keyword.
640 67115 Calcos can leave a gap at the top of an NUV DQ image.
645 67204 Add a TIMELINE extension to calcos corrtag files.
657 67439 Modify the calcos command-line arguments for the csum file.
661 67473 Calcos should not always re-do wavecorr for corrtag input.
670 67553 Calcos uses malloc/free in C interface in some functions.
  67675 COS csum header information will only be correct if used with the --only_csum option
702 68209 A "walk" correction needs to be added to calcos.
707 68355 For COS FUV, splittag and x1dcorr use wrong EXPTIME keyword.
717 68529 Calcos should compute the FWHM when finding a spectrum.
718 68538 Update deprecated Python syntax in calcos.
719 68545 Calcos needs an option to use the default location for the target spectrum.
720 68550 Calcos should accept data taken with different cenwaves.
735 68712 Change calcos import statements for boxcar.
736 68713 Background smoothing in calcos includes some bad regions.

Overview

  • A bug in background smoothing during spectral extraction has been fixed. The smoothing was being affected by zero values of the background near the endpoints, where all pixels were flagged as bad in the DQ extension. A bug that prevented using a corrtag file as input to calcos has been fixed.
  • When the input to calcos is a tagflash corrtag file, the wavelength calibration will only be re-done if keyword wavecorr is set to perform. Previously, this step would be repeated if wavecorr was either perform or complete, but this would be inappropriate if the corrtag file had been split by time, e.g. by running splittag.
  • For FUV input data with WAVECORR = COMPLETE (e.g. corrtag input), if very verbose trailer info was specified (-v), a warning message was printed regarding the lampflash tables. This warning was not necessary and could be misleading; it should no longer be printed for this case.
  • The source files for tasks splittag and x1dcorr were modified to use segment-specific keywords for exposure time, for FUV data. This affects columns ERROR and GCOUNTS in the x1d table.
  • A new TIMELINE extension will be added to corrtag files, giving the altitude of the Sun, the longitude and latitude of HST, and other information at one-second intervals throughout the exposure.
  • For FUV data, the pixel coordinates of a detected photon differ from the actual location at which the photon hit the detector (this is referred to as "walk").  The offset is a function of the pulse height amplitude (PHA). The changes to calcos allow corrections to the XCORR and YCORR pixel coordinates to be computed as polynomial functions of XCORR and YCORR. This is applied after the thermal and geometric corrections.
  • For G140L data, the wavecal shifts are normally copied from segment A to segment B.  If there is no segment A data, however, calcos used to attempt to find the wavecal shift. There is no significant wavecal signal for segment B, so the attempt always failed and sometimes gave a shift that was quite far off. Now if there is no segment A data, calcos will set the wavecal shifts to zero for segment B.
  • When extracting the spectrum, the FWHM of the cross-dispersion (Y) profile and the error estimate of the spectrum location in the Y direction are now printed, in addition to the expected and found locations.
  • For FUV TIME-TAG data, the lower and upper thresholds for pulse height may now be specified by images instead of a table, allowing different limits at different points one the detector. The new reference file has keyword PHAFILE.  (However, no such reference file has been created yet.) If PHAFILE is present in the primary header, and if its value is not N/A, the specified file will be used instead of the PHATAB table to do the PHACORR.  For ACCUM data the PHATAB must still be used.
  • Most of the doc strings have been modified to use Sphinx syntax.
  • If a csum file is to be created, and if raw pixel coordinates should be used instead of corrected coordinates (relevant only for FUV), some of the calibration switch keywords were set to COMPLETE in the csum header, which is misleading because it would not be true for the csum file. These keywords will now be set to OMIT if the option to use raw coordinates (--raw) was specified.

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https://hsthelp.stsci.edu.