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mperrin / webbpsf

James Webb Space Telescope PSF simulation tool - NOTE THIS VERSION OF REPO IS SUPERCEDED BY spacetelescope/webbpsf
BSD 3-Clause "New" or "Revised" License
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docs: explain more about NIRCam auto-channel toggling and how it interacts with other options #216

Closed mperrin closed 5 years ago

mperrin commented 6 years ago

Via email from @obi-wan76:

In calc_psf, the description for the monochromatic parameter reads that it overrides the filter and nlambda setting. However, a simple monochromatic PSF for a default NIRCam configuration at a wavelength outside the range of the default filter (‘F200W’) will give an error


nc=webbpsf.NIRCam()
nircam300 = nc.calcPSF(monochromatic= 3.e-6)

“RuntimeError: The requested wavelengths are too long for NIRCam short wave channel.”



> So, it is confusing because the description reads that a monochromatic PSF will override the filter, implying that it may automatically assume a filter within that range (with the given that a W,M and N filter won’t make a difference for a monochromatic PSF) .
mperrin commented 6 years ago

Answer: Monochromatic mode will override the filter, but as a result it doesn't engage the automatic toggling between SW and LW channels. The workaround is straightforward, just do something to toggle to LW first: e.g. nc.filter='F444W'

This could potentially be fixed with a wrapper to calc_psf for NIRCam to activate the toggle for monochromatic modes, if necessary.