nb6. Query by frequency

import numpy as np
import astropy
import pyvo
import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle

service = pyvo.dal.TAPService("https://almascience.eso.org/tap")      # for the EU ALMA TAP service

# service = pyvo.dal.TAPService("https://almascience.nao.ac.jp/tap")  # for the EA ALMA TAP service
# service = pyvo.dal.TAPService("https://almascience.nrao.edu/tap")   # for the NA ALMA TAP service

def query_spectral_range(service, science_category, freq_min, freq_max):
    """Returns all observations that have (a portion of) their spectral coverage overlapping the range freq_min to freq_max
        
       service               pyvo TAPService instance
       science_category      (substring of) one of the ALMA science science categories (see +Notebook 4)
       freq_min              minimum frequency of the requested coverage (GHz)
       freq_max              maximum frequency of the requested coverage (GHz)
              
       returns               pandas table with frequency (GHz) and bandwidth (GHz)
    """

    query = f"""   
            SELECT member_ous_uid, target_name, frequency, bandwidth
            FROM ivoa.obscore   
            WHERE (frequency - 0.5 * bandwidth/1e9) < {freq_max} AND (frequency + 0.5 * bandwidth/1e9) > {freq_min} AND scientific_category like '%{science_category}%'
            """
    
    return service.search(query).to_table().to_pandas()

def plot_all_frequencies(output_table):
    """Plots the frequencies and bandwidths for all of the observations in the output table
    
    output_table      pandas output table with frequency (GHz) and bandwidth (Hz) column
    
    returns           None   
    """

    plt.rcParams["figure.figsize"] = (20,20)
    fig, ax = plt.subplots()
    ax.plot([0,len(output_table['frequency'])],[84,480], alpha = 0)
    
    for i in range(len(output_table['frequency'])):
        freq_min = output_table['frequency'][i] - output_table['bandwidth'][i]/1e9/2
        freq_max = output_table['frequency'][i] + output_table['bandwidth'][i]/1e9/2
        left, bottom, width, height = (i, freq_min, 0.5,  freq_max - freq_min )
        ax.add_patch(Rectangle((left,bottom), width, height))

    ### Code each band
    ax.add_patch(Rectangle((-3,84),2,116-84,   facecolor = 'blue'))
    ax.add_patch(Rectangle((-3,125),2,163-125, facecolor = 'red'))
    ax.add_patch(Rectangle((-3,163),2,211-163, facecolor = 'green'))
    ax.add_patch(Rectangle((-3,211),2,275-211, facecolor = 'orange'))
    ax.add_patch(Rectangle((-3,275),2,373-275, facecolor = 'yellow'))
    ax.add_patch(Rectangle((-3,385),2,500-385, facecolor = 'magenta'))

    plt.title('Frequency coverage for "SPT0311-58"',fontsize=15)
    plt.xlabel('Observations',fontsize=15)
    plt.ylabel('Frequency [GHz]',fontsize=15)

output = query_spectral_range(service, 'Active galaxies', 200, 400)

query = f"""SELECT * FROM ivoa.obscore WHERE target_name = 'SPT0311-58'"""
result = service.search(query)
output = result.to_table().to_pandas()