Plot DESI Lyman-alpha SNR

In [1]:

    

%pylab inline
import numpy as np
import matplotlib.pyplot as plt
import spectrograph as sp


    

    




Populating the interactive namespace from numpy and matplotlib

In [2]:

    

def plot_quasar(spec,z,mag,lobs):
    label='z='+str(z)+', mag='+str(mag)
    Nl = len(l)
    noise = np.empty(Nl)
    for i in range(Nl):
        noise[i] = spec.PixelNoiseRMS(mag,z,l[i],1.0)
    plt.plot(l,noise,label=label)


    

In [3]:

    

#create spectrograph object 
band='r'
spec = sp.Spectrograph(band)
lmin,lmax = spec.range_lobs_A()


    

In [4]:

    

# make plot of SNR for a couple of quasar (z,mag)
l = np.linspace(lmin,lmax,1000)
plot_quasar(spec,z=2.5,mag=22.0,lobs=l)
plot_quasar(spec,z=2.5,mag=22.5,lobs=l)
plot_quasar(spec,z=3.0,mag=22.0,lobs=l)
plot_quasar(spec,z=3.0,mag=22.5,lobs=l)
plt.legend(fontsize=15)
plt.ylim(0,2.0)
plt.xlim(3600,6000)
plt.xlabel('wavelength [A]',fontsize=15)
plt.ylabel('pixel noise',fontsize=15)
if band is 'r':
    plt.title('Lya SNR as a function of quasar (z, r mag)')
elif band is 'g':
    plt.title('Lya SNR as a function of quasar (z, g mag)')
else:
    print('bad band in plot_noise',band)
    raise SystemExit


    

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