Space Telescope Imaging Spectrograph
MKFRINGEFLAT: Make Fringe Flats for the STIS CCD Long Wavelength Fringing

There are two problems with the version of mkfringeflat currently in the stis package. One has to do with a change to Python, because of which mkfringeflat will not run in PyRAF, although it will still run in the IRAF CL. The change is that the result of dividing integers will be a floating-point value. This will not be the default until Python 3, but our Python code, including PyRAF, has been modified to include this change. This affects a cl script running in PyRAF because the cl script is converted internally to Python. mkfringeflat.cl divides axis lengths by the binning, and the result is used in constructing an image section. IRAF tasks will not accept an image name if the limits of the image section are floats. The workaround for this problem is to run mkfringeflat in the IRAF CL rather than in PyRAF.

The second issue is only a problem if the input fringe flat was taken as a subarray (note that this is not the usual case). There is no workaround for this. If the fringe flat is a subarray, then you will need to use the updated version of mkfringeflat.cl.

To use the new version of mkfringeflat, copy mkfringeflat.cl to some directory (referred to below as ), load the stis package, and redefine the mkfringeflat task, e.g.:

    --> stis
    --> redefine mkfringeflat = /mkfringeflat.cl