This notebook demonstrates and tests the SpectralEfficiency effect for the METIS long-slit spectroscopic modes. Lacking real data, the grating effciencies used here (and available in the irdb) are pure fantasy.

import scopesim as sim

sim.bug_report()

# Edit this path if you have a custom install directory, otherwise comment it out.
sim.rc.__config__["!SIM.file.local_packages_path"] = "../../../../"

import numpy as np
from astropy.io import fits
from astropy.io import ascii as ioascii
from astropy import units as u
from matplotlib import pyplot as plt
%matplotlib inline

If you haven’t got the instrument packages yet, uncomment the following cell.

# sim.download_packages(["METIS", "ELT", "Armazones"])

Source – constant spectrum

from synphot import SourceSpectrum, Empirical1D
from scopesim_templates.micado import flatlamp

lam = np.linspace(2.8, 18, 2048)
flux = 0.1 * np.ones_like(lam)
spec = SourceSpectrum(Empirical1D, points = lam * u.um, lookup_table=flux)

src = flatlamp()
src.spectra[0] = spec

L band

cmd_l = sim.UserCommands(use_instrument='METIS', set_modes=['lss_l'])

metis_l = sim.OpticalTrain(cmd_l)

metis_l['psf'].include = False                # PSF is not necessary for slit-filling source
metis_l['skycalc_atmosphere'].include = False # sky lines obscure flat spectrum

Observe the source with and without the grating efficiency. The ratio between the two results (we look at the image plane, which is noise free) shows directly the efficiency. As long as no realistic data are available, the efficiency effect is turned off by default and has to be included explicitely.

metis_l['grating_efficiency'].include  = True
metis_l.observe(src)
sim_l_with_effic = metis_l.image_planes[0].data

metis_l['grating_efficiency'].include = False
metis_l.observe(src, update=True)
sim_l_without_effic = metis_l.image_planes[0].data

ratio_l = sim_l_with_effic / sim_l_without_effic
plt.figure(figsize=(15, 5))
plt.subplot(131)
plt.imshow(sim_l_with_effic, origin='lower')
plt.title("L band, with grating efficiency")
plt.subplot(132)
plt.imshow(sim_l_without_effic, origin='lower')
plt.title("L band, without grating efficiency")
plt.subplot(133)
plt.imshow(ratio_l, origin='lower')
plt.title("L band, ratio");

plt.plot((sim_l_with_effic / sim_l_without_effic)[:, 1000]);

M band

cmd_m = sim.UserCommands(use_instrument='METIS', set_modes=['lss_m'])
metis_m = sim.OpticalTrain(cmd_m)

metis_m['psf'].include = False                # PSF is not necessary for slit-filling source
metis_m['skycalc_atmosphere'].include = False # sky lines obscure flat spectrum

metis_m['grating_efficiency'].include  = True
metis_m.observe(src, update=True)
sim_m_with_effic = metis_m.image_planes[0].data

metis_m['grating_efficiency'].include = False
metis_m.observe(src, update=True)
sim_m_without_effic = metis_m.image_planes[0].data

ratio_m = sim_m_with_effic / sim_m_without_effic
plt.figure(figsize=(15, 5))
plt.subplot(131)
plt.imshow(sim_m_with_effic, origin='lower')
plt.title("M band, with grating efficiency")
plt.subplot(132)
plt.imshow(sim_m_without_effic, origin='lower')
plt.title("M band, with grating efficiency")
plt.subplot(133)
plt.imshow(ratio_m, origin='lower')
plt.title("M band, ratio");

plt.plot(ratio_m[:, 1000]);

N band

cmd_n = sim.UserCommands(use_instrument='METIS', set_modes=['lss_n'])
metis_n = sim.OpticalTrain(cmd_n)

metis_n['psf'].include = False                # PSF is not necessary for slit-filling source
metis_n['skycalc_atmosphere'].include = False # sky lines obscure flat spectrum

metis_n['grating_efficiency'].include  = True
metis_n.observe(src, update=True)
sim_n_with_effic = metis_n.image_planes[0].data

metis_n['grating_efficiency'].include = False
metis_n.observe(src, update=True)
sim_n_without_effic = metis_n.image_planes[0].data

ratio_n = sim_n_with_effic / sim_n_without_effic
plt.figure(figsize=(15, 5))
plt.subplot(131)
plt.imshow(sim_n_with_effic, origin='lower')
plt.title("N band, with grating efficiency")
plt.subplot(132)
plt.imshow(sim_n_without_effic, origin='lower')
plt.title("N band, with grating efficiency")
plt.subplot(133)
plt.imshow(ratio_n, origin='lower')
plt.title("N band, ratio");

plt.plot(ratio_n[:, 1000]);