make_spectrum.py
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#! /usr/bin/env python
# ==========================================================================
# This script shows how to make a spectrum using obsutils.
#
# Copyright (C) 2014-2015 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
import cscripts
try:
import matplotlib.pyplot as plt
has_matplotlib = True
except:
has_matplotlib = False
# =============== #
# Make a spectrum #
# =============== #
def make_spectrum():
"""
Make a spectrum.
"""
# Set script parameters
model_name = "${CTOOLS}/share/models/crab.xml"
caldb = "prod2"
irf = "South_50h"
ra = 83.63
dec = 22.01
rad_sim = 3.0
tstart = 0.0
tstop = 1800.0
emin = 0.1
emax = 100.0
enumbins = 10
# Simulate events
sim = ctools.ctobssim()
sim["inmodel"] = model_name
sim["caldb"] = caldb
sim["irf"] = irf
sim["ra"] = ra
sim["dec"] = dec
sim["rad"] = rad_sim
sim["tmin"] = tstart
sim["tmax"] = tstop
sim["emin"] = emin
sim["emax"] = 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)
# Setup csspec run
spec = cscripts.csspec(sim.obs())
spec["srcname"] = "Crab"
spec["outfile"] = "spectrum.fits"
spec["expcube"] = "NONE"
spec["psfcube"] = "NONE"
spec["bkgcube"] = "NONE"
spec["edisp"] = False
spec["emin"] = emin
spec["emax"] = emax
spec["enumbins"] = enumbins
spec["binned"] = False
spec.run()
# Get copy of spectrum
spectrum = spec.spectrum().copy()
# Return
return spectrum
# ============= #
# Plot spectrum #
# ============= #
def plot_spectrum(spectrum):
"""
Plot spectrum.
"""
# Read spectrum file
table = spectrum.table(1)
c_energy = table["Energy"]
c_ed = table["ed_Energy"]
c_eu = table["eu_Energy"]
c_flux = table["Flux"]
c_eflux = table["e_Flux"]
c_ts = table["TS"]
c_upper = table["UpperLimit"]
# Initialise arrays to be filled
energies = []
flux = []
ed_engs = []
eu_engs = []
e_flux = []
ul_energies = []
ul_ed_engs = []
ul_eu_engs = []
ul_flux = []
# Loop over rows of the file
nrows = table.nrows()
for row in range(nrows):
# Get TS
ts = c_ts.real(row)
flx = c_flux.real(row)
e_flx = c_eflux.real(row)
# Switch
if ts > 9.0 and e_flx < flx:
# Add information
energies.append(c_energy.real(row))
flux.append(c_flux.real(row))
ed_engs.append(c_ed.real(row))
eu_engs.append(c_eu.real(row))
e_flux.append(c_eflux.real(row))
#
else:
# Add information
ul_energies.append(c_energy.real(row))
ul_flux.append(c_upper.real(row))
ul_ed_engs.append(c_ed.real(row))
ul_eu_engs.append(c_eu.real(row))
# Create figure
plt.figure()
plt.title("Crab spectrum")
# Plot the spectrum
plt.loglog()
plt.grid()
plt.errorbar(energies, flux, yerr=e_flux, xerr=[ed_engs, eu_engs], fmt='ro')
plt.errorbar(ul_energies, ul_flux, xerr=[ul_ed_engs, ul_eu_engs], yerr=1.0e-11, uplims=True, fmt='ro')
plt.xlabel("Energy (TeV)")
plt.ylabel(r"dN/dE (erg cm$^{-2}$ s$^{-1}$)")
# 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)