l3_psf

romanisim.l3.l3_psf(bandpass, scale=0, chromatic=False, **kw)

Construct a PSF for an L3 image.

The challenge here is that the L3 PSF has gone through drizzling which broadens the PSF relative to the native PSF. We treat this here by doing the following:

• we start with the native PSF for the appropriate bandpass for SCA 2 (no pixel convolution)

• we convolve that with a box of size sqrt(1-scale**2) pixel

• we return the result

So for a very small scale you still get a convolution by the full native pixel scaling (since the image was ultimately observed with the Roman detectors and needs to be seen through that grid), but you get oversampled output. There will always be an additional convolution with the output pixel scale. In the limit that the output pixel scale is 1, this does nothing, but provides undersampled output.

Extra arguments are passed to romanisim.psf.make_psf.

Parameters:

scalefloat

The output mosaic pixel scale. Must be between 0 and 1.

bandpassstr

The filter to use

chromaticbool

if True, generate a chromatic PSF rather than an achromatic PSF. This is intended for use with galsim chromatic sources.

Returns:

galsim.Profile object for use as the PSF