rv_shift.py

from __future__ import print_function
import glob
from os import path
import numpy as np
import pandas as pd
from matplotlib import pyplot as plt
from astropy import units as u
from astropy import constants as c


def read_spectra(filen):
    df = pd.read_csv(filen, names=['wavel', 'intens'], sep=' ', skiprows=1)
    return df


def plot_spectra(filen):
    cen_wavel = 6569.53  # Angstroms
    del_wavel = 0.5
    ref = read_spectra('ReferenceSpectrum.txt')
    obs = read_spectra(filen)
    ref['velo'] = (ref['wavel'] - cen_wavel) / cen_wavel * c.c.to('km/s').value
    obs['velo'] = (obs['wavel'] - cen_wavel) / cen_wavel * c.c.to('km/s').value
    fig, ax = plt.subplots()
    ax.step(ref.velo, ref.intens, where='mid', color='red', label='Ref')
    ax.step(obs.velo, obs.intens, where='mid', color='black', label='Obs')
    ax.set_xlim([-10, +10])
    ax.set_xlabel('Velocity [km / s]')
    ax.set_ylabel('Intensity')
    ax.legend()
    ax.grid()
    plt.savefig(path.splitext(filen)[0] + '.pdf')
    plt.close()


def plot_all():
    for filen in glob.glob('Group*.txt'):
        plot_spectra(filen)