GNIRS LS reduction: nswavelength error

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    Hello, I’m attempting to reduce some GNIRS long slit spectra (10/mmLR_G5532 grating, central wavelength ~3.5 microns).

    I’ve installed Geminiconda and progressed through a few initial reduction steps (nsheader, nsprepare, nsreduce, nsflats) without too much difficulty.

    However, I’m stuck at nswavelength. I’m providing a calibration star spectrum as the input for wavelength calibration. nswavelength does not request an output spectrum, and then the following occurs:

    –> nswavelength
    Input GNIRS/NIRI lamp spectra: /Users/User/Desktop/data/Gemini/GNIRS/nN20160810S0263.fits
    NSWAVELENGTH — Wed Jun 20 12:48:50 PDT 2018

    NSWAVELENGTH: LS data detected. Calling nswhelper to process data.
    NSWHELPER — Wed Jun 20 12:48:50 PDT 2018

    Using input files:
    Using output files:
    NSAPPWAVE — Wed Jun 20 12:48:50 PDT 2018

    NSAPPWAVE: Processing 1 extension(s) from 1 file(s).
    Camera Grating Filter Prism FPMask Wave Delta Order Axis
    Killing IRAF task `fxcopy’
    Traceback (innermost last):
    File “<CL script CL1>”, line 1, in <module>
    File “<CL script gnirs.nswavelength>”, line 298, in nswavelength

    [… skipping the iraf.nswhelper text to shorten this post… ]

    File “<CL script gnirs.nsappwave>”, line 289, in nsappwave
    iraf.fxcopy(Vars.inimg + ‘.fits’, Vars.outimg + ‘.fits’,group = ‘0’,new_file=yes,verbose=no)
    IrafError: Error running IRAF task fxcopy
    IRAF task terminated abnormally
    ERROR (741, “Cannot open file (w/Users/User/Desktop/data/Gemini/GNIRS/nN20160810S0263.fits)”)

    It appears that nswavelength is looking for an output file in the “w” directory, but this directory doesn’t exist. I tried to manually generate a “w” directory just to see if I could work around this error, but it still crashes with the same issue.

    I’m using Gemini IRAF package 1.14, installed on a Mac: Yosemite 10.10.5. I installed the package using the instructions provided on the Gemini data reduction pages.

    Any guidance would be greatly appreciated!


    IRAF is trying to create an output filename by putting a “w” (for wavelength) at the front of your input filename. Unfortunately, it’s not smart enough to distinguish between the part of the filename that’s the path, and the part that’s the actual filename.

    The solution is to run nswavelength from the directory where your files are (/Users/User/Desktop/data/Gemini/GNIRS/) and to only specify the filename of the input file, not the path.

    Hope that helps!

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