make_spectrum.py
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#! /usr/bin/env python
# ==========================================================================
# This script shows how to make a spectrum using obsutils.
#
# Copyright (C) 2014 Juergen Knoedlseder
#
# 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 GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# ==========================================================================
import gammalib
import ctools
try:
import matplotlib.pyplot as plt
has_matplotlib = True
except:
has_matplotlib = False
# =============== #
# Make a spectrum #
# =============== #
def make_spectrum():
"""
"""
# Set script parameters
model_name = "${CTOOLS}/share/models/crab.xml"
caldb = "dummy"
irf = "cta_dummy_irf"
ra = 83.63
dec = 22.01
rad_sim = 3.0
tstart = 0.0
tstop = 1800.0
emin = 0.1
emax = 100.0
# Simulate events
sim = ctools.ctobssim()
sim["infile"].filename(model_name)
sim["caldb"].string(caldb)
sim["irf"].string(irf)
sim["ra"].real(ra)
sim["dec"].real(dec)
sim["rad"].real(rad_sim)
sim["tmin"].real(tstart)
sim["tmax"].real(tstop)
sim["emin"].real(emin)
sim["emax"].real(emax)
sim.run()
# Generate an energy binning
e_min = gammalib.GEnergy(emin, "TeV")
e_max = gammalib.GEnergy(emax, "TeV")
ebounds = gammalib.GEbounds(10, e_min, e_max)
# Generate spectral points
spectrum = ctools.obsutils.spectrum(sim.obs(), "Crab", ebounds)
# Return spectrum
return spectrum
# ============= #
# Plot spectrum #
# ============= #
def plot_spectrum(spectrum):
"""
Plot spectrum.
"""
# Create figure
plt.figure(1)
plt.title("Crab spectrum")
# Plot spectrum
plt.loglog(spectrum['energy']['value'], \
spectrum['flux']['value'], 'ro', label='Crab')
plt.errorbar(spectrum['energy']['value'], \
spectrum['flux']['value'], \
spectrum['flux']['ed_value'], fmt=None, ecolor='r')
# Put labels
plt.xlabel("Energy ("+spectrum['energy']['unit']+")")
plt.ylabel("Flux ("+spectrum['flux']['unit']+")")
plt.legend(loc="lower left")
# Show spectrum
plt.show()
# Return
return
#==========================#
# Main routine entry point #
#==========================#
if __name__ == '__main__':
"""
Generate a Crab spectrum.
"""
# Generate spectrum
spectrum = make_spectrum()
# Plot spectrum
if has_matplotlib:
plot_spectrum(spectrum)