Rotational spectra
==================
.. code-block:: python
    :name: Rotational spectra
    :linenos:

    import pyarts
    import numpy as np
    
    # Limit the frequency range of stored absorption lines
    fmin = 0
    fmax = 3e12
    
    # initialize ARTS
    ws = pyarts.workspace.Workspace()
    
    # Download ARTS catalogs if they are not already present.
    pyarts.cat.download.retrieve()
    
    # We are setting up our absorption species to include hydrogen chloride,
    # chlorine monoxide, carbon monoxide, nitrous oxide, and ozone
    # To speed up calculations some, we limit ourself to absorption lines with less
    # than 3 THz as their central frequency
    # NOTE: Limiting the frequency range of absorption lines like this artificially
    # removes absorption from the wings of stronger absorption lines that lie
    # outside of the given freqeuncy range.  This migth affect the accuracy of the
    # total absorption that is computed
    ws.abs_speciesSet(
        species=[f"HCl-*-{fmin}-{fmax}",
                 f"ClO-*-{fmin}-{fmax}",
                 f"CO-*-{fmin}-{fmax}",
                 f"N2O-*-{fmin}-{fmax}",
                 f"O3-*-{fmin}-{fmax}"])
    
    # Read the absorption lines.  These should be part of the arts-cata-data package
    ws.abs_lines_per_speciesReadSpeciesSplitCatalog(basename="lines/")
    
    # Use an automatic agenda
    ws.propmat_clearsky_agendaAuto()
    
    # Arts setup (No NLTE, no polarization, and standard isotopologue ratios)
    ws.nlte_do = 0
    ws.stokes_dim = 1
    ws.isotopologue_ratiosInitFromBuiltin()
    
    # Settings (Standard atmosphere midlatitude-summer)
    ws.Touch(ws.jacobian_quantities)
    ws.Touch(ws.select_abs_species)
    ws.Touch(ws.rtp_nlte)
    ws.rtp_mag = [10e-6, 20e-6, 40e-6]
    ws.rtp_los = [45, 45]
    ws.rtp_pressure = 110000
    ws.rtp_temperature = 2.942000e+02
    ws.f_grid = np.linspace(1e9, 3e12, 1000)
    ws.rtp_vmr = [1.000869e-09, 1.000869e-14,
                  2.850472e-06, 1.501303e-07, 3.019448e-08]
    
    # Check that the calculations are OK
    ws.lbl_checkedCalc()
    
    # Start the explorer
    ws.propmat_clearsky_agendaGUI()