CALSTIS Version 2.17 was released on 2004-Nov-11 in the new STSDAS release, Version 3.3, which can be found on the STSDAS Download Page. This version of CALSTIS was installed in the OTFR pipeline as part of OPUS 15.5 build on 2005-January-24.

The following OPRs are implemented in the release of CALSTIS 2.17:

OPR 51667:	CALSTIS mkfringeflat should process data containing subarrays.*
OPR 49488:	CALSTIS time-dependent sensitivity correction for imaging mode
OPR 49489:	CALSTIS should use the EPC file temperatures instead of OCCDHTAV
OPR 50503:	CALSTIS6 should not include background in x1d error calculation
OPR 51666:	CALSTIS should have a post-processing task to align dithered spectra. SSHIFT (New task)
OPR 51734:	Calstis4 for echelle wavecal taken with long slit
OPR 51786:	Include another clipping step in CALSTIS for overscan region
OPR 52112:	STIS STSDAS package should have tasks to convert image xy pixels to/from RA/Dec. TRXYEQ, TREQXY, UCRPIX (New tasks)

* An error in the final build of the STSDAS 3.3 package caused several IRAF scripts for the fringe-flat tasks in the STIS package to be corrupted. The affected tasks are: PREPSPEC, NORMSPFLAT, MKFRINGEFLAT, and DEFRINGE. The corrected versions of these scripts and instructions for installing them into STSDAS can be downloaded from http://www.stsci.edu/resources/software_hardware/stsdas/download

Below we give more details on changes that are likely to be noticed by users in their data.

OPR 51667: CALSTIS mkfringeflat should process data containing subarrays (NORMSPFLAT, MKFRINGEFLAT, DEFRINGE).

The fringe-flat tasks, NORMSPFLAT, MKFRINGEFLAT, and DEFRINGE, have been modified to handle subarrays and binned images. They have also been modified to run under PyRAF. The flat-field file is now by default obtained from the header of the input file rather than from a task parameter. As a result, the PREPSPEC task is now depreciated.

OPR 49488: CALSTIS time-dependent sensitivity correction for imaging mode

In CALSTIS 2.17 the calculations for PHOTFLAM and other photometric keywords in the headers of STIS imaging mode observations now include the effects of time-dependent sensitivity changes. This is especially important for the UV imaging modes, where some filters show mean throughput changes of as much as 2.5% per year. It is assumed that imaging modes show the same time-dependent sensitivity changes as the first-order low-dispersion modes (see STIS ISR 2004-04). Note that the OTFR pipeline currently includes the reference files needed to calculate the time-dependent sensitivity changes in the headers of STIS imaging data, but it will not automatically apply these corrections to imaging mode photometric keyword calculations until CALSTIS 2.17 is installed in the pipeline.

OPR 49489: CALSTIS should use the EPC file temperatures instead of OCCDHTAV

CALSTIS can now use the new EPC tables (engineering products for calibration) to get the temperatures for correcting the CCD sensitivity for its dependence on temperature for Side-2 data (i.e., data taken since 2001-Jul-01).

OPR 50503: CALSTIS6 should not include background in x1d error calculation

In the 1-D spectral extraction step of CALSTIS (X1D), background smoothing is done for most data, but the calculation of the ERROR column still included a significant contribution from the background regions, which was calculated assuming an un-smoothed background. CALSTIS now does not include any contribution to the error from the background subtraction if background smoothing has been done.

OPR 51666: CALSTIS should have a post-processing task to align dithered spectra. SSHIFT (New task)

SSHIFT is a new PyRAF post-processing task for aligning dithered spectral images. The dithering must be along the slit and use integer pixel shifts. The output images can then be combined with ocrreject, which will reject hot pixels in the same way that it rejects cosmic rays. The POSTARG2 and BINAXIS2 keywords are used to determine the number of rows to be shifted. The shifts will be applied toward the center of the CCD.

OPR 51734: CALSTIS4 for echelle wavecal taken with long slit

An 'angle' parameter has been added to the wavecal task and to the hidden task _cs4; it may be necessary to unlearn both of these tasks (or "unlearn stis"). This parameter should normally be left at its default value of INDEF. However, for echelle wavecal data taken with a long slit (e.g., 6X0.2), the angle of the slit images on the detector can be as large as ~6 degrees, and specifying an appropriate value for 'angle' will significantly improve the accuracy of wavecal processing.

OPR 51786: Include another clipping step in CALSTIS for overscan region

Some STIS CCD data have a "hot" column with very high counts that extends down into the virtual overscan region. This can adversely affect the fit for the bias overscan subtraction. An additional clipping step has been added to CALSTIS to look for outliers within the entire virtual overscan region. This gives an improved fit and a more reliable bias subtraction.

OPR 52112: STIS STSDAS package should have tasks to convert image xy pixels to/from RA/Dec. TRXYEQ, TREQXY, UCRPIX (New tasks)

These tasks have been added to the stis package. The first two of these tasks are for converting between pixel coordinates and right ascension and declination in STIS images, taking into account the optical distortion. UCRPIX shifts the world coordinate system for a STIS image to force a given pixel location to be at a user-specified RA and DEC.

Full details of the changes to CALSTIS are described in the release notes for CALSTIS 2.17.
http://www.stsci.edu/resources/software_hardware/stsdas/relnotes/releasenotes