3.6 Updates to calstis

The calstis modules are improved and new versions are released as more knowledge becomes available. These improvements could produce more accurately calibrated data even when using the same reference files.

To determine the version of the software used to calibrate STIS data, note the value of the CAL_VER keyword in the primary header. The following example uses astropy.io.fits to print the rootname, the optical element, and the version of calstis for all _flt files in the current directory:

>>> from astropy.io.fits import fits
>>> hdr = fits.getheader('odbue5040_x1d.fits',0)
>>> print(hdr['ROOTNAME'], hdr['OPT_ELEM'], hdr['CAL_VER']

Keep up to date with the STScI Analysis Newsletters (STANs) or consult the STIS website for any announcement of enhancements to calstis. 

If you are uncertain whether a given enhancement to calstis merits recalibrating of any given data, contact the Help Desk. Often, it is instructive to re-calibrate (or simply re-request the data from the archive) and to determine empirically whether the revised calibration files or software affect the scientific interpretation of the data. If you need to upgrade your version of the stistools package, please refer to https://stenv.readthedocs.io/en/latest/.