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refactor handling of slit apertures in aperturename setter, to suppor…
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…t MIRI as well as NIRSpec. For LRS slit.
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@mperrin
mperrin committed Dec 22, 2023
1 parent b45e76f commit a89a0ea
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18 changes: 17 additions & 1 deletion webbpsf/tests/test_miri.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
import logging
import os

import astropy.units as u
import pysiaf
import numpy as np

_log = logging.getLogger('test_webbpsf')
Expand Down Expand Up @@ -71,3 +72,18 @@ def test_miri_aperturename():
assert miri.detector_position == (128, 128), "Changing to a subarray aperture didn't change the " \
"reference pixel coords as expected"
assert np.any( miri._tel_coords() != ref_tel_coords), "Changing to a subarray aperture didn't change the V2V3 coords as expected."


def test_miri_slit_apertures():
"""Test that we can use slit and aperture names that don't map to a specific detector
Verify that the V2 and V3 coordinates are reported as expected.
"""
miri = webbpsf_core.MIRI()

apname = "MIRIM_SLIT" # this is the only slit aperture on the MIRI imager
miri.set_position_from_aperture_name(apname)

ap = pysiaf.Siaf('MIRI')[apname]

assert np.isclose(miri._tel_coords()[0].to_value(u.arcsec), ap.V2Ref)
assert np.isclose(miri._tel_coords()[1].to_value(u.arcsec), ap.V3Ref)
135 changes: 47 additions & 88 deletions webbpsf/webbpsf_core.py
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Original file line number Diff line number Diff line change
Expand Up @@ -919,30 +919,50 @@ def aperturename(self, value):
except KeyError:
raise ValueError(f'Aperture name {value} not a valid SIAF aperture name for {self.name}')

if self.detector not in value:
raise ValueError(f'Aperture name {value} does not match currently selected detector {self.detector}. '
f'Change detector attribute first, then set desired aperture.')

# Only update if new value is different
if self._aperturename != value:
# First, check some info from current settings, wich we will use below as part of auto pixelscale code
# The point is to check if the pixel scale is set to a custom or default value,
# and if it's custom then don't override that.
# Note, check self._aperturename first to account for the edge case when this is called from __init__ before _aperturename is set
has_custom_pixelscale = self._aperturename and (self.pixelscale != self._get_pixelscale_from_apername(self._aperturename))

# Now apply changes:
self._aperturename = value
# Update detector reference coordinates
self.detector_position = (ap.XSciRef, ap.YSciRef)
if ap.AperType == 'SLIT':
# Special case for SLIT apertures (NIRSpec and MIRI)
# apertures of type SLIT define V2,V3 position, but not pixel coordinates and pixelscale. So we
# still have to use a full-detector aperturename for that subset of apertures
detector_apername = self.detector + "_FULL"
_log.info(f'Aperture {value} is of type SLIT; using {detector_apername} for detector geometry.')

# Update DetectorGeometry class
self._detector_geom_info = DetectorGeometry(self.siaf, self._aperturename)
_log.info(f"{self.name} SIAF aperture name updated to {self._aperturename}")
has_custom_pixelscale = self._aperturename and (self.pixelscale != self._get_pixelscale_from_apername(detector_apername))

if not has_custom_pixelscale:
self.pixelscale = self._get_pixelscale_from_apername(self._aperturename)
_log.debug(f"Pixelscale updated to {self.pixelscale} based on average X+Y SciScale at SIAF aperture {self._aperturename}")
# Now apply changes:
self._aperturename = value

# Update DetectorGeometry class
self._detector_geom_info = DetectorGeometry(self.siaf, self._aperturename)
_log.info(f"{self.name} SIAF aperture name updated to {self._aperturename} using geometry from {detector_apername}")
if not has_custom_pixelscale:
self.pixelscale = self._get_pixelscale_from_apername(detector_apername)
_log.debug(f"Pixelscale updated to {self.pixelscale} based on average X+Y SciScale at SIAF aperture {detector_apername}")
else:
if self.detector not in value:
raise ValueError(f'Aperture name {value} does not match currently selected detector {self.detector}. '

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f'Change detector attribute first, then set desired aperture.')

# First, check some info from current settings, wich we will use below as part of auto pixelscale code
# The point is to check if the pixel scale is set to a custom or default value,
# and if it's custom then don't override that.
# Note, check self._aperturename first to account for the edge case when this is called from __init__ before _aperturename is set
has_custom_pixelscale = self._aperturename and (self.pixelscale != self._get_pixelscale_from_apername(self._aperturename)) and ap.AperType != 'SLIT'

# Now apply changes:
self._aperturename = value
# Update detector reference coordinates
self.detector_position = (ap.XSciRef, ap.YSciRef)

# Update DetectorGeometry class
self._detector_geom_info = DetectorGeometry(self.siaf, self._aperturename)
_log.info(f"{self.name} SIAF aperture name updated to {self._aperturename}")

if not has_custom_pixelscale:
self.pixelscale = self._get_pixelscale_from_apername(self._aperturename)
_log.debug(f"Pixelscale updated to {self.pixelscale} based on average X+Y SciScale at SIAF aperture {self._aperturename}")


def _tel_coords(self):
Expand All @@ -953,7 +973,13 @@ def _tel_coords(self):
dimensional Quantity.
"""

return self._detector_geom_info.pix2angle(self.detector_position[0], self.detector_position[1])
if self._detector_geom_info.aperture.AperType=='SLIT':
# These apertures don't map directly to particular detector position in the usual way
# Return coords for center of the aperture reference location
return np.asarray((self._detector_geom_info.aperture.V2Ref,
self._detector_geom_info.aperture.V3Ref)) / 60 * units.arcmin
else:
return self._detector_geom_info.pix2angle(self.detector_position[0], self.detector_position[1])

def _xan_yan_coords(self):
""" Convert from detector pixel coordinates to the XAN, YAN coordinate system
Expand Down Expand Up @@ -989,6 +1015,7 @@ def set_position_from_aperture_name(self, aperture_name):
# NIRSpec slit apertures need some separate handling, since they don't map directly to detector pixels
# In this case the detector position is not uniquely defined, but we ensure to get reasonable values by
# using one of the full-detector NIRspec apertures
_log.debug("Inferring detector position using V coords for SLIT aperture: {ap.V2Ref, ap.V3Ref}")
ref_in_tel = ap.V2Ref, ap.V3Ref
nrs_full_aperture = self.siaf[self.detector + "_FULL"]
ref_in_sci = nrs_full_aperture.tel_to_sci(*ref_in_tel)
Expand Down Expand Up @@ -2597,74 +2624,6 @@ def _get_fits_header(self, hdulist, options):
hdulist[0].header['APERTURE'] = (str(self.image_mask), 'NIRSpec slit aperture name')


@JWInstrument.aperturename.setter
def aperturename(self, value):
"""Set SIAF aperture name to new value, with validation.
This also updates the pixelscale to the local value for that aperture, for a small precision enhancement.
Similar to superclass function, but handles the more complex situation with NIRSpec apertures and detectors
"""
# Explicitly update detector reference coordinates to the default for the new selected aperture,
# otherwise old coordinates can persist under certain circumstances

try:
ap = self.siaf[value]
except KeyError:
raise ValueError(f'Aperture name {value} not a valid SIAF aperture name for {self.name}')

# NIRSpec apertures can either be per detector (i.e. "NRS1_FULL") or for the focal plane but not per detector (i.e. "NRS_FULL_IFU")

if value[0:4] in ['NRS1', 'NRS2']:
# this is a regular per-detector aperture, so just call the regular code in the superclass
JWInstrument.aperturename.fset(self, value)
else:
# apertures that start with NRS define V2,V3 position, but not pixel coordinates and pixelscale. So we
# still have to use a full-detector aperturename for that.
detector_apername = self.detector + "_FULL"

# Only update if new value is different
if self._aperturename != value:
# First, check some info from current settings, which we will use below as part of auto pixelscale code
# The point is to check if the pixel scale is set to a custom or default value,
# and if it's custom then don't override that.
# Note, check self._aperturename first to account for the edge case when this is called from __init__ before _aperturename is set
has_custom_pixelscale = self._aperturename and (self.pixelscale != self._get_pixelscale_from_apername(detector_apername))

# Now apply changes:
self._aperturename = value
# Update detector reference coordinates
# self.detector_position = (ap.XSciRef, ap.YSciRef)

# Update DetectorGeometry class
self._detector_geom_info = DetectorGeometry(self.siaf, self._aperturename)
_log.info(f"{self.name} SIAF aperture name updated to {self._aperturename}")

if not has_custom_pixelscale:
self.pixelscale = self._get_pixelscale_from_apername(detector_apername)
_log.debug(f"Pixelscale updated to {self.pixelscale} based on average X+Y SciScale at SIAF aperture {self._aperturename}")



def _tel_coords(self):
""" Convert from science frame coordinates to telescope frame coordinates using
SIAF transformations. Returns (V2, V3) tuple, in arcminutes.
Note that the astropy.units framework is used to return the result as a
dimensional Quantity.
Some extra steps for NIRSpec to handle the more complicated/flexible mapping between detector and sky coordinates
"""

if self.aperturename.startswith("NRS_"):
# These apertures don't map directly to particular detector position in the usual way
# Return coords for center of the aperture reference location
return np.asarray((self._detector_geom_info.aperture.V2Ref,
self._detector_geom_info.aperture.V3Ref)) / 60 * units.arcmin
else:
return super()._tel_coords()



class NIRISS(JWInstrument):
""" A class modeling the optics of the Near-IR Imager and Slit Spectrograph
Expand Down

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