#
# LSST Data Management System
# Copyright 2008, 2009, 2010, 2011, 2012 LSST Corporation.
#
# This product includes software developed by the
# LSST Project (http://www.lsst.org/).
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the LSST License Statement and
# the GNU General Public License along with this program. If not,
# see <http://www.lsstcorp.org/LegalNotices/>.
#
__all__ = ("Bandpass", "rubin_bandpasses")
import gzip
import os
import warnings
import numpy as np
try:
from numpy import trapezoid as trapezoid
except ImportError:
from numpy import trapz as trapezoid
import scipy.interpolate as interpolate
from rubin_sim.data import get_data_dir
from .physical_parameters import PhysicalParameters
from .sed import Sed
[docs]
def rubin_bandpasses():
"""Return the standard expected Rubin filter bandpasses."""
filterlist = ["u", "g", "r", "i", "z", "y"]
dd = get_data_dir()
filter_dict = {}
for f in filterlist:
filter_dict[f] = Bandpass()
filter_dict[f].read_throughput(os.path.join(dd, "throughputs", "baseline", f"total_{f}.dat"))
return filter_dict
[docs]
class Bandpass:
"""
Hold and use telescope throughput curves.
Parameters
----------
wavelen : `np.ndarray`, (N,)
Wavelength array in nm.
sb : `np.ndarray`, (N,)
Throughput array (fraction, 0-1).
sampling_warning : `float`
If wavelength sampling lower than this,
throw a warning because it might provide accurate magnitudes
due to how magnitudes are calculated in Sed (nm).
"""
def __init__(self, wavelen=None, sb=None, sampling_warning=0.2):
self._phys_params = PhysicalParameters()
self.sampling_warning = sampling_warning
self.wavelen = None
self.sb = None
self.phi = None
self.bandpassname = None
if (wavelen is not None) and (sb is not None):
self.set_bandpass(wavelen, sb)
return
[docs]
def set_bandpass(self, wavelen, sb):
"""
Populate bandpass data with wavelen/sb arrays.
Phi set to None.
Parameters
----------
wavelen : `np.ndarray`, (N,)
Wavelength array in nm.
sb : `np.ndarray`, (N,)
Throughput array (fraction, 0-1).
Raises
------
ValueError
Raised if ``wavelen`` and ``sb`` have different length.
"""
# Check data type.
if (isinstance(wavelen, np.ndarray) is False) or (isinstance(sb, np.ndarray) is False):
raise ValueError("Wavelen and sb arrays must be numpy arrays.")
# Check data matches in length.
if len(wavelen) != len(sb):
raise ValueError("Wavelen and sb arrays must have the same length.")
self.wavelen = np.copy(wavelen)
self.phi = None
self.sb = np.copy(sb)
self.bandpassname = "FromArrays"
[docs]
def imsim_bandpass(self, imsimwavelen=500.0, wavelen_min=300, wavelen_max=1150, wavelen_step=0.1):
"""
Populate bandpass data with sb=0 everywhere except at imsimwavelen.
Sets wavelen/sb, with grid min/max/step as Parameters.
"""
# Set up arrays.
self.wavelen = np.arange(
wavelen_min,
wavelen_max + wavelen_step,
wavelen_step,
dtype="float",
)
self.phi = None
# Set sb.
self.sb = np.zeros(len(self.wavelen), dtype="float")
self.sb[abs(self.wavelen - imsimwavelen) < wavelen_step / 2.0] = 1.0
self.bandpassname = "IMSIM"
[docs]
def read_throughput(self, filename):
"""
Populate bandpass data with data (wavelen/sb) read from file.
Sets wavelen/sb. Does NOT set phi.
"""
# Set self values to None in case of file read error.
self.wavelen = None
self.phi = None
self.sb = None
# Check for filename error.
# If given list of filenames,
# pass to (and return from) read_throughputList.
if isinstance(filename, list):
warnings.warn(
"Was given list of files, instead of a single file. Using read_throughputList instead"
)
self.read_throughput_list(component_list=filename)
# Filename is single file, now try to open file and read data.
try:
if filename.endswith(".gz"):
f = gzip.open(filename, "rt")
else:
f = open(filename, "r")
except IOError:
try:
if filename.endswith(".gz"):
f = open(filename[:-3], "r")
else:
f = gzip.open(filename + ".gz", "rt")
except IOError:
raise IOError("The throughput file %s does not exist" % (filename))
# The throughput file should have [wavelength(A), throughput(Sb)]
wavelen = []
sb = []
for line in f:
if line.startswith("#") or line.startswith("$") or line.startswith("!"):
continue
values = line.split()
if len(values) < 2:
continue
if (values[0] == "$") or (values[0] == "#") or (values[0] == "!"):
continue
wavelen.append(float(values[0]))
sb.append(float(values[1]))
f.close()
self.bandpassname = filename
# Set up wavelen/sb.
self.wavelen = np.array(wavelen, dtype="float")
self.sb = np.array(sb, dtype="float")
# Check that wavelength is monotonic increasing and
# non-repeating in wavelength. (Sort on wavelength).
if len(self.wavelen) != len(np.unique(self.wavelen)):
raise ValueError("The wavelength values in file %s are non-unique." % (filename))
# Sort values.
p = self.wavelen.argsort()
self.wavelen = self.wavelen[p]
self.sb = self.sb[p]
[docs]
def read_throughput_list(
self,
component_list=(
"detector.dat",
"lens1.dat",
"lens2.dat",
"lens3.dat",
"m1.dat",
"m2.dat",
"m3.dat",
"atmos_std.dat",
),
root_dir=".",
wavelen_min=300,
wavelen_max=1150,
wavelen_step=0.1,
):
"""
Populate bandpass data by reading from a series of files
containing wavelen/Sb data.
Multiplies throughputs (sb) from each file to give a final
bandpass throughput.
Sets wavelen/sb, with grid min/max/step as Parameters.
Does NOT set phi.
"""
# ComponentList = names of files in that directory.
# A typical component list of all files to build final component list,
# including filter, might be:
# ['detector.dat', 'lens1.dat', 'lens2.dat', 'lens3.dat',
# 'm1.dat', 'm2.dat', 'm3.dat', 'atmos_std.dat', 'ideal_g.dat']
#
# Set up wavelen/sb on grid.
self.wavelen = np.arange(
wavelen_min,
wavelen_max + wavelen_step / 2.0,
wavelen_step,
dtype="float",
)
self.phi = None
self.sb = np.ones(len(self.wavelen), dtype="float")
# Set up a temporary bandpass object to hold data from each file.
tempbandpass = Bandpass()
for component in component_list:
# Read data from file.
with warnings.catch_warnings():
warnings.simplefilter("ignore")
tempbandpass.read_throughput(os.path.join(root_dir, component))
tempbandpass.resample_bandpass(
wavelen_min=wavelen_min,
wavelen_max=wavelen_max,
wavelen_step=wavelen_step,
)
# Multiply self by new sb values.
self.sb = self.sb * tempbandpass.sb
self.bandpassname = "".join(component_list)
def get_bandpass(self):
wavelen = np.copy(self.wavelen)
sb = np.copy(self.sb)
return wavelen, sb
# utilities
[docs]
def check_use_self(self, wavelen, sb):
"""
Simple utility to check if should be using self.wavelen/sb
or passed arrays.
Useful for other methods in this class.
Also does data integrity check on wavelen/sb if not self.
"""
update_self = False
if (wavelen is None) or (sb is None):
# Then one of the arrays was not passed - check if true for both.
if (wavelen is not None) or (sb is not None):
# Then only one of the arrays was passed - raise exception.
raise ValueError("Must either pass *both* wavelen/sb pair, or use self defaults")
# Okay, neither wavelen or sb was passed in - using self only.
update_self = True
else:
# Both of the arrays were passed in - check their validity.
if (isinstance(wavelen, np.ndarray) is False) or (isinstance(sb, np.ndarray) is False):
raise ValueError("Must pass wavelen/sb as numpy arrays")
if len(wavelen) != len(sb):
raise ValueError("Must pass equal length wavelen/sb arrays")
return update_self
[docs]
def resample_bandpass(
self,
wavelen=None,
sb=None,
wavelen_min=300,
wavelen_max=1150,
wavelen_step=0.1,
):
"""
Resamples wavelen/sb (or self.wavelen/sb) onto grid
defined by min/max/step.
Either returns wavelen/sb (if given those arrays) or
updates wavelen / Sb in self. If updating self, resets phi to None.
"""
# Check wavelength limits.
wavelen_min = wavelen_min
wavelen_max = wavelen_max
wavelen_step = wavelen_step
# Is method acting on self.wavelen/sb or passed in wavelen/sb?
update_self = (wavelen is None) & (sb is None)
if update_self:
wavelen = self.wavelen
sb = self.sb
# Now, on with the resampling.
if (wavelen.min() > wavelen_max) or (wavelen.max() < wavelen_min):
raise Exception("No overlap between known wavelength range and desired wavelength range.")
# Set up gridded wavelength.
wavelen_grid = np.arange(wavelen_min, wavelen_max + wavelen_step / 2.0, wavelen_step, dtype="float")
# Do the interpolation of wavelen/sb onto the grid.
# (note wavelen/sb type failures will die here).
f = interpolate.interp1d(wavelen, sb, fill_value=0, bounds_error=False)
sb_grid = f(wavelen_grid)
# Update self values if necessary.
if update_self:
self.phi = None
self.wavelen = wavelen_grid
self.sb = sb_grid
return
return wavelen_grid, sb_grid
# more complicated bandpass functions
[docs]
def sb_tophi(self):
"""
Calculate and set phi - the normalized system response.
This function only updates self.phi.
"""
# The definition of phi = (Sb/wavelength)/\int(Sb/wavelength)dlambda.
self.phi = self.sb / self.wavelen
# Normalize phi so that the integral of phi is 1.
norm = trapezoid(self.phi, x=self.wavelen)
self.phi = self.phi / norm
return
[docs]
def multiply_throughputs(self, wavelen_other, sb_other):
"""
Multiply self.sb by another wavelen/sb pair, return wavelen/sb arrays.
The returned arrays will be gridded like this bandpass.
This method does not affect self.
"""
# Resample wavelen_other/sb_other to match this bandpass.
if not np.all(self.wavelen == wavelen_other):
wavelen_other, sb_other = self.resample_bandpass(
wavelen=wavelen_other,
sb=sb_other,
wavelen_min=self.wavelen.min(),
wavelen_max=self.wavelen.max(),
wavelen_step=self.wavelen[1] - self.wavelen[0],
)
# Make new memory copy of wavelen.
wavelen_new = np.copy(self.wavelen)
# Calculate new transmission - this is also new memory.
sb_new = self.sb * sb_other
return wavelen_new, sb_new
[docs]
def calc_zp_t(self, photometric_parameters):
"""
Calculate the instrumental zeropoint for a bandpass.
Parameters
----------
photometric_parameters : `PhotometricParameters`
Details about the photometric response of the telescope.
Defaults to LSST values.
"""
# ZP_t is the magnitude of a (F_nu flat) source which produced
# 1 count per second.
# This is often also known as the 'instrumental zeropoint'.
# Set gain to 1 if want to explore photo-electrons rather than adu.
# The typical LSST exposure time is 15s and this is default here,
# but typical zp_t definition is for 1s.
# SED class uses flambda in ergs/cm^2/s/nm, so need effarea in cm^2.
#
# Check dlambda value for integral.
self.wavelen[1] - self.wavelen[0]
# Set up flat source of arbitrary brightness,
# but where the units of fnu are Jansky (for AB mag zeropoint = -8.9).
flatsource = Sed()
flatsource.set_flat_sed()
adu = flatsource.calc_adu(self, phot_params=photometric_parameters)
# Scale fnu so that adu is 1 count/expTime.
flatsource.fnu = flatsource.fnu * (1 / adu)
# Now need to calculate AB magnitude of the source with this fnu.
if self.phi is None:
self.sb_tophi()
zp_t = flatsource.calc_mag(self)
return zp_t
[docs]
def calc_eff_wavelen(self):
"""
Calculate effective wavelengths for filters.
"""
# This is useful for summary numbers for filters.
# Calculate effective wavelength of filters.
if self.phi is None:
self.sb_tophi()
effwavelenphi = (self.wavelen * self.phi).sum() / self.phi.sum()
effwavelensb = (self.wavelen * self.sb).sum() / self.sb.sum()
return effwavelenphi, effwavelensb
[docs]
def write_throughput(self, filename, print_header=None, write_phi=False):
"""
Write throughput to a file.
"""
# Useful if you build a throughput up from components
# and need to record the combined value.
f = open(filename, "w")
# Print header.
if print_header is not None:
if not print_header.startswith("#"):
print_header = "#" + print_header
f.write(print_header)
if write_phi:
if self.phi is None:
self.sb_tophi()
print("# Wavelength(nm) Throughput(0-1) Phi", file=f)
else:
print("# Wavelength(nm) Throughput(0-1)", file=f)
# Loop through data, printing out to file.
for i in range(0, len(self.wavelen), 1):
if write_phi:
print(self.wavelen[i], self.sb[i], self.phi[i], file=f)
else:
print(self.wavelen[i], self.sb[i], file=f)
f.close()
