Tutorial script for running BNS event GW170817

examples/open_data_examples/GW170817.py

+#!/usr/bin/env python
+"""
+This tutorial includes advanced specifications
+for analysing binary neutron star event data.
+Here GW170817 is used as an example.
+"""
+from __future__ import division, print_function
+import bilby
+
+outdir = 'outdir'
+label = 'GW170817'
+time_of_event = bilby.gw.utils.get_event_time(label)
+bilby.core.utils.setup_logger(outdir=outdir, label=label)
+# GET DATA FROM INTERFEROMETER
+# include 'V1' for appropriate O2 events
+interferometer_names = ['H1', 'L1', 'V1']
+duration = 32
+roll_off = 0.2  # how smooth is the transition from no signal
+# to max signal in a Tukey Window.
+psd_offset = -512  # PSD is estimated using data from
+# `center_time+psd_offset` to `center_time+psd_offset + psd_duration`
+# This determines the time window used to fetch open data.
+psd_duration = 1024
+coherence_test = False  # coherence between detectors
+filter_freq = None  # low pass filter frequency to cut signal content above
+# Nyquist frequency. The condition is 2 * filter_freq >= sampling_frequency
+
+
+# All keyword arguments are passed to
+# `gwpy.timeseries.TimeSeries.fetch_open_data()'
+kwargs = {}
+# Data are stored by LOSC at 4096 Hz, however
+# there may be event-related data releases with a 16384 Hz rate.
+kwargs["sample_rate"] = 4096
+# For O2 events a "tag" is required to download the data.
+# CLN = clean data; C00 or C01 = raw data
+kwargs["tag"] = 'C00'
+interferometers = bilby.gw.detector.get_event_data(
+    label,
+    interferometer_names=interferometer_names,
+    duration=duration,
+    roll_off=roll_off,
+    psd_offset=psd_offset,
+    psd_duration=psd_duration,
+    cache=True,
+    filter_freq=filter_freq,
+    **kwargs)
+# CHOOSE PRIOR FILE
+prior = bilby.gw.prior.BNSPriorDict(filename='binary_neutron_stars.prior')
+deltaT = 0.1
+prior["geocent_time"] = bilby.core.prior.Uniform(
+    minimum=time_of_event - deltaT / 2,
+    maximum=time_of_event + deltaT / 2,
+    name="geocent_time",
+    latex_label="$t_c$",
+    unit="$s$")
+# GENERATE WAVEFORM
+# OVERVIEW OF APPROXIMANTS:
+# https://www.lsc-group.phys.uwm.edu/ligovirgo/cbcnote/Waveforms/Overview
+duration = None  # duration and sampling frequency will be overwritten
+# to match the ones in interferometers.
+sampling_frequency = kwargs["sample_rate"]
+start_time = 0  # set the starting time of the time array
+waveform_arguments = {
+    'waveform_approximant': 'TaylorF2', 'reference_frequency': 20}
+
+source_model = bilby.gw.source.lal_binary_neutron_star
+waveform_generator = bilby.gw.WaveformGenerator(
+    duration=duration,
+    sampling_frequency=sampling_frequency,
+    start_time=start_time,
+    frequency_domain_source_model=source_model,
+    waveform_arguments=waveform_arguments,)
+
+# CHOOSE LIKELIHOOD FUNCTION
+# Time marginalisation uses FFT.
+# Distance marginalisation uses a look up table calculated at run time.
+# Phase marginalisation is done analytically using a Bessel function.
+likelihood = bilby.gw.likelihood.GravitationalWaveTransient(
+    interferometers,
+    waveform_generator,
+    time_marginalization=False,
+    distance_marginalization=False,
+    phase_marginalization=False,)
+
+# RUN SAMPLER
+# Implemented Samplers:
+# LIST OF AVAILABLE SAMPLERS: Run -> bilby.sampler.implemented_samplers
+# conversion function = bilby.gw.conversion.generate_all_bns_parameters
+npoints = 512
+sampler = 'dynesty'
+result = bilby.run_sampler(
+    likelihood,
+    prior,
+    outdir=outdir,
+    label=label,
+    sampler=sampler,
+    npoints=npoints,
+    use_ratio=False,
+    injection_parameters=None,
+    conversion_function=None)
+result.plot_corner()