Instruments

A chart view of the interactions of different models with the Instrument

GalPaK uses a virtual Instrument to convolve the simulation cubes and check against observed data. As each instrument has its own tweaks and quirks (both hardware and atmospheric), you can provide an instrument to GalPaK3D, the default one being MUSE in Wide Field Mode :

The spectral characteristics (pixel cdelt, etc.) are re-calibrated using the Cube’s header when you instantiate GalPaK. Pay attention in defining most appropriate values for the seeing or psf_fwhm(“) – psf_ba if not round – and lsf_fwhm (in units of cube) parameters. All of them by default use the gaussian PSF GaussianPointSpreadFunction.

Instruments handling

You should define the instrument as :

from galpak import GalPaK3D, MUSE, GaussianPointSpreadFunction
mypsf = GaussianPointSpreadFunction(fwhm=0.7,pa=0,ba=1)
myinstr = MUSE(psf=mypsf,lsf=None)
gk = GalPaK3D('GalPaK_cube_1101_from_paper.fits',instrument=myinstr)

And print(gk.instrument) should yield

[INSTRUMENT] :
type = MUSE
pixscale = 0.2 “

[PSF] :
type = gaussian
fwhm = 0.7 “
pa = 0 °
ba = 1
[LSF] :
type = Gaussian
fwhm = 2.5369617016 Angstrom

cube_xy_step = 0.2 “
cube_z_step = 1.25 Angstrom

cube z_step_kms = 57.12979890310786 km/s at 6564.0 Angstrom

Note

The galpak save method will save a file instrument.txt

If the instrument is saved into a instrument.txt file, one can use :

from galpak import GalPaK3D
gk = GalPaK3D('GalPaK_cube_1101_from_paper.fits',instrument='instrument.txt')

The file instrument.txt should be like :

[INSTRUMENT] :
type = MUSE
pixscale = 0.2 “

[PSF] :
type = gaussian
fwhm = 0.7 “
pa = 0 °
ba = 1
[LSF] :
type = Gaussian
fwhm = 2.5369617016 Angstrom

Note

Both instrument.txt and model.txt can be combined in a single config file

Instruments supported

  • ALMA

    set lsf_fwhm to 1 cdelt (default) or less or use NoLineSpreadFunction

  • SINFONI (J250, H250 and K250 modes)

    SINFOJ250, SINFOH250, SINFOK250 :

    from galpak import run, SINFOK250

    gk = run(‘my_sinfok250_cube.fits’, instrument=SINFOK250())

  • MUSE (WFM and NFW modes)

    default lsf_fwhm is 2.67 Angstrom

  • KMOS

    default xy_step is 0.2 arcsecs

  • HARMONI

    use the syntax HARMONI(pixscale=30)

  • OSIRIS

  • MANGA (soon)

Note

The default Instrument values will be overridden by the cube header info (CRPIX, CDELT etc.) if present.

Base Instrument Class