Version 9.5 of the ISO Off-Line Processing (OLP) software released on 28 November 2000

Release note on CAM OLP Version 9.5

Two major CAM changes of the ISO pipeline version 9.5 which have implications for the science data are:
  1. The deglitching is now performed by using the Multiresolution Median Transform method (see Section 8.2.1 of the CAM Handbook, v1.1).

  2. To correct for the transient behaviour of the LW detector, the Fouks-Schubert method is applied (see Section 4.4 of the CAM Handbook, v1.1).

These changes are only applied on LW detector data. The caveats for this version can be found in Appendix E of the CAM Handbook v1.1.

Joris Blommaert (IDC Vilspa), Stephan Ott (IDC Vilspa), Diego Cesarsky (MPE Garching).

Release note on SWS OLP Version 9.5

This is the first revision of the SWS pipeline since OLP 8.4 in August 1999. The main area of change for users is in the Derive-SPD section, which has been extensively modified. Derive-AAR was only slightly changed (see point 6).

While the major difference between versions for the developers, the change in programming language from Fortran to IDL, is invisible to the users, it was carried out in order to make the Derive-SPD part of the OLP software available for general users OSIA. The conversion also allows a better development enviroment for improvements. The entire Derive-SPD pipeline has been reviewed during the re-coding process and a number of minor bugs have been identified and fixed.

Changes to Derive-SPD, wrt the version in the SWS Handbook, include:

1. `Correction for reset pulse effects' is now done after `Correction of the integration ramp for the RC time constant' rather than before.

2. The SWS Consortium defines the pulse-shape as the after-effect of the reset-pulse applied after each reset interval. It manifests itself as an exponential curve with typical decay times of 0.25 - 0.5 seconds and a typical amplitude of 20 - 50 uV. The pulse-shape is an additive component added to the integrated signal of the detector and the impact on the observed slope depends on the gain setting of the instrument.

The correction itself is a plain subtraction of the pulse-shape. However, the difficulty here is to find the right pulse-shape.

It was first believed that the pulse-shape could be corrected for with a single set of pulse-shapes (one for each detector). This was implemented for OLP Version 4.3 (using calfile 02B), but deactivated for later versions, and assumed that the effect of the after-reset pulse was constant. Since then it was learned that this is not the case and that the pulse-shape can change from observation to observation and sometimes also change within one observation.

OLP 9.5 corrects for the pulse-shape on an observation to observation basis and in some cases also on individual parts within one observations. Consequently it does not rely on a fixed type of calibration but use the data itself to do the calibration.

3. Glitch handling is improved, helped also by the above modification. However, this has excacerbated the problem of glitch detection confusing gltches with spectral lines in fast AOT1 observations.

4. Slope calculation is improved in the case of glitches by using a model for fitting and an 'intelligent' sample skipping algorithm. For cases where the slopes contain no glitches, the slope calculation remains unchanged.

5. The post-helium observations are correctly wavelength calibrated, although not flux calibrated.

6. The application of the internal calibrator data to the flux calibration in the pipeline has been corrected to match the internal calibrator data used in the derivation of the absolute flux calibration. The net result is higher fluxes in bands 2,3,4 and the FP bands on the order of ~10%, ~5%, ~5% and ~5%, respectively.

All these changes will be discussed fully in the new version of the SWS Handbook, due in December.

K. Leech, A. Salama, R. Shipman, E. Wieprecht, B. Vandenbussche for the SWS consortium.