GONG helper functions

import os

import numpy as np


def get_gong_map():
    """
    Automatically download and unzip a sample GONG synoptic map.
    """
    if not os.path.exists('190310t0014gong.fits') and not os.path.exists('190310t0014gong.fits.gz'):
        import urllib.request
        urllib.request.urlretrieve(
            'https://gong2.nso.edu/oQR/zqs/201903/mrzqs190310/mrzqs190310t0014c2215_333.fits.gz',
            '190310t0014gong.fits.gz')

    if not os.path.exists('190310t0014gong.fits'):
        import gzip
        with gzip.open('190310t0014gong.fits.gz', 'rb') as f:
            with open('190310t0014gong.fits', 'wb') as g:
                g.write(f.read())

    return '190310t0014gong.fits'