Allow for all (non-imaging) Roman bands internally

galsim/roman/__init__.py

@@ -99,7 +99,7 @@
 # Maxinum allowed angle from the telecope solar panels to the sun in degrees.
 max_sun_angle = 36.
 
-from .roman_bandpass import getBandpasses
+from .roman_bandpass import getBandpass, getBandpasses
 from .roman_backgrounds import getSkyLevel
 from .roman_psfs import getPSF
 from .roman_wcs import getWCS, findSCA, allowedPos, bestPA, convertCenter

galsim/roman/roman_bandpass.py

@@ -26,10 +26,11 @@
 import os
 
 from .. import meta_data
-from ..errors import galsim_warn
+from ..errors import GalSimValueError, galsim_warn
 from .. import Bandpass, LookupTable
 
-def getBandpasses(AB_zeropoint=True, default_thin_trunc=True, include_all_bands=False, **kwargs):
+def getBandpasses(AB_zeropoint=True, default_thin_trunc=True, include_all_bands=False, bandnames=None,
+    **kwargs):
     """Utility to get a dictionary containing the Roman ST bandpasses used for imaging.
 
     This routine reads in a file containing a list of wavelengths and throughput for all Roman
@@ -96,6 +97,9 @@ def getBandpasses(AB_zeropoint=True, default_thin_trunc=True, include_all_bands=
                             There is currently no estimate for the thermal background for these
                             bands and they are set to zero arbitrarily.
                             [default: False]
+        bandnames:          Iterable of bandpass names to get. If None, it gets all the imaging
+                            bands if ``include_all_bands`` is False, or all bands if
+                            ``include_all_bands`` is True.
         **kwargs:           Other kwargs are passed to either `Bandpass.thin` or
                             `Bandpass.truncate` as appropriate.
 
@@ -109,11 +113,19 @@ def getBandpasses(AB_zeropoint=True, default_thin_trunc=True, include_all_bands=
     data = np.genfromtxt(datafile, names=True)
     wave = 1000.*data['Wave']
 
+    if bandnames is None:
+        bandnames = data.dtype.names[1:]
+    elif (invalid_bandnames := set(bandnames).difference(data.dtype.names[1:])):
+        raise GalSimValueError("Invalid Roman bandpasses requested;",
+                               value=invalid_bandnames,
+                               allowed_values=data.dtype.names[1:],
+                               )
+
     # Read in and manipulate the sky background info.
     sky_file = os.path.join(meta_data.share_dir, "roman", "roman_sky_backgrounds.txt")
-    sky_data = np.loadtxt(sky_file).transpose()
-    ecliptic_lat = sky_data[0, :]
-    ecliptic_lon = sky_data[1, :]
+    sky_data = np.genfromtxt(sky_file, names=True)
+    ecliptic_lat = sky_data['Latitude']
+    ecliptic_lon = sky_data['Longitude']
 
     # Parse kwargs for truncation, thinning, etc., and check for nonsense.
     truncate_kwargs = ['blue_limit', 'red_limit', 'relative_throughput']
@@ -138,7 +150,7 @@ def getBandpasses(AB_zeropoint=True, default_thin_trunc=True, include_all_bands=
     # Set up a dictionary.
     bandpass_dict = {}
     # Loop over the bands.
-    for index, bp_name in enumerate(data.dtype.names[1:]):
+    for bp_name in bandnames:
         if include_all_bands is False and bp_name in non_imaging_bands:
             continue
 
@@ -160,10 +172,36 @@ def getBandpasses(AB_zeropoint=True, default_thin_trunc=True, include_all_bands=
         # Store the sky level information as an attribute.
         bp._ecliptic_lat = ecliptic_lat
         bp._ecliptic_lon = ecliptic_lon
-        bp._sky_level = sky_data[2+index, :]
+        bp._sky_level = sky_data[bp_name]
 
         # Add it to the dictionary.
         bp.name = bp_name if bp_name != 'W149' else 'W146'
         bandpass_dict[bp.name] = bp
 
     return bandpass_dict
+
+def getBandpass(bandname, AB_zeropoint=True, default_thin_trunc=True, **kwargs):
+    """Utility to get a single bandpass from the Roman ST bandpasses used.
+
+    If you need to get more than one bandpass, use `getBandpasses` instead.
+    This function just provides a cleaner interface when only one bandpass
+    is needed.
+
+    See also `getBandpasses`.
+
+    Parameters:
+        bandname:           Name of the bandpass to get.
+        AB_zeropoint:       Should the routine set an AB zeropoint before returning the bandpass?
+                            If False, then it is up to the user to set a zero point.  [default:
+                            True]
+        default_thin_trunc: Use the default thinning and truncation options?  Users who wish to
+                            use no thinning and truncation of bandpasses, or who want control over
+                            the level of thinning and truncation, should have this be False.
+                            [default: True]
+        **kwargs:           Other kwargs are passed to either `Bandpass.thin` or
+                            `Bandpass.truncate` as appropriate.
+
+    @returns A Bandpass object for the specified band.
+    """
+    return getBandpasses(AB_zeropoint=AB_zeropoint, default_thin_trunc=default_thin_trunc,
+                          include_all_bands=True, bandnames=[bandname], **kwargs)[bandname]

galsim/roman/roman_config.py

@@ -20,7 +20,7 @@
 from . import n_pix, exptime, dark_current, read_noise, gain
 from . import stray_light_fraction, thermal_backgrounds
 from .roman_psfs import getPSF
-from .roman_bandpass import getBandpasses
+from .roman_bandpass import getBandpass, getBandpasses
 from .roman_wcs import getWCS
 from .roman_backgrounds import getSkyLevel
 from ..config import ParseAberrations, BandpassBuilder, GetAllParams, GetRNG
@@ -112,7 +112,7 @@ def buildBandpass(self, config, base, logger):
             from ..deprecated import depr
             depr('W149', 2.5, 'W146', 'Note: this is to match current Roman filter naming schemes')
             name = 'W146'
-        bandpass = getBandpasses()[name]
+        bandpass = getBandpass(name)
 
         return bandpass, safe
 
@@ -200,7 +200,7 @@ def setup(self, config, base, image_num, obj_num, ignore, logger):
 
     def getBandpass(self, filter_name):
         if not hasattr(self, 'all_roman_bp'):
-            self.all_roman_bp = getBandpasses()
+            self.all_roman_bp = getBandpasses(include_all_bands=True)
         return self.all_roman_bp[filter_name]
 
     def addNoise(self, image, config, base, image_num, obj_num, current_var, logger):

galsim/roman/roman_psfs.py

@@ -22,7 +22,7 @@
 from . import pixel_scale, n_pix, pixel_scale_mm
 from . import n_pix, n_sca, longwave_bands, shortwave_bands
 from . import diameter, obscuration
-from .roman_bandpass import getBandpasses
+from .roman_bandpass import getBandpass
 
 from ..utilities import LRU_Cache
 from ..position import PositionD
@@ -335,8 +335,7 @@ def _get_single_PSF(SCA, bandpass, SCA_pos, pupil_bin,
                                   aper=aper, gsparams=gsparams)
         if n_waves is not None:
             # To decide the range of wavelengths to use, check the bandpass.
-            bp_dict = getBandpasses()
-            bp = bp_dict[bandpass]
+            bp = getBandpass(bandpass)
             PSF = PSF.interpolate(waves=np.linspace(bp.blue_limit, bp.red_limit, n_waves),
                                   oversample_fac=1.5)
     else:

share/roman/roman_sky_backgrounds.txt

@@ -1,3 +1,4 @@
+# Latitude Longitude R062 Z087 Y106 J129 H158 F184 W146 K213 SNPrism Grism_1stOrder Grism_0thOrder
 0.0000 0.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000
 1.3976 0.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000
 2.7960 0.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000 -10.0000

tests/test_roman.py

@@ -513,6 +513,43 @@ def test_roman_nonimaging_bandpass():
     assert 'Grism_1stOrder' not in bp_imaging
     assert 'SNPrism' not in bp_imaging
 
+@timer
+def test_roman_bandpass_subsets():
+    """Test that we can get a subset of Roman bandpasses.
+    """
+    bandnames = ["J129", "H158"]
+    bp_dict = galsim.roman.getBandpasses(bandnames=bandnames)
+
+    # Check that the imaging bandpasses are a subset of the all bandpasses
+    for bandname in bandnames:
+        assert bandname in bp_dict
+        bp_dict.pop(bandname)
+
+    # Check that we have no bandpasses left
+    assert len(bp_dict) == 0
+
+    # Test that we get an error for invalid bandpasses
+    with assert_raises(galsim.GalSimValueError):
+        galsim.roman.getBandpasses(bandnames=["u", "g", "r", "i"])
+
+@timer
+def test_roman_single_bandpass():
+    """Test getting a single bandpass from the Roman bandpass utility.
+    """
+    bp = galsim.roman.getBandpass('F184')
+    assert bp.name == 'F184'
+
+    # Check that the default values are the same for getBandpass and getBandpasses.
+    bp_dict = galsim.roman.getBandpasses()
+    assert bp == bp_dict[bp.name]
+
+    # Explicitly check for the W-band, since that's a special case.
+    bp = galsim.roman.getBandpass("W146")
+    assert bp == bp_dict[bp.name]
+
+    # Test for a non-imaging bandpass.
+    bp = galsim.roman.getBandpass("SNPrism")
+    assert bp.name == "SNPrism"
 
 @timer
 def test_roman_detectors():