"""
Methods for importing data from the Cassini spacecraft.
"""
import datetime
import os
import pathlib
import pandas as pd
import calendar
import astropy.units as u
from collections import OrderedDict
from heliopy.data import util
from heliopy import config
data_dir = pathlib.Path(config['download_dir'])
use_hdf = config['use_hdf']
cassini_dir = data_dir / 'cassini'
# These mappings from months to strings are used in directory names
month2str = {1: '001_031_JAN',
2: '032_059_FEB',
3: '060_090_MAR',
4: '091_120_APR',
5: '121_151_MAY',
6: '152_181_JUN',
7: '182_212_JUL',
8: '213_243_AUG',
9: '244_273_SEP',
10: '274_304_OCT',
11: '305_334_NOV',
12: '335_365_DEC'}
leapmonth2str = {1: '001_031_JAN',
2: '032_060_FEB',
3: '061_091_MAR',
4: '092_121_APR',
5: '122_152_MAY',
6: '153_182_JUN',
7: '183_213_JUL',
8: '214_244_AUG',
9: '245_274_SEP',
10: '275_305_OCT',
11: '306_335_NOV',
12: '336_366_DEC'}
class _mag1minDownloader(util.Downloader):
def __init__(self, coords):
valid_coords = ['KRTP', 'KSM', 'KSO', 'RTN']
if coords not in valid_coords:
raise ValueError('coords must be one of {}'.format(valid_coords))
self.coords = coords
Rs = u.def_unit('saturnRad', 60268 * u.km)
if (coords == 'KRTP'):
self.units = OrderedDict([('Bx', u.nT), ('By', u.nT), ('Bz', u.nT),
('X', Rs), ('|B|', u.nT),
('Y', u.deg),
('Z', u.deg),
('Local hour', u.dimensionless_unscaled),
('n points', u.dimensionless_unscaled)])
if (coords == 'RTN'):
self.units = OrderedDict([('Bx', u.nT), ('By', u.nT), ('Bz', u.nT),
('X', u.AU), ('Y', u.AU), ('Z', u.AU),
('|B|', u.nT),
('Local hour', u.dimensionless_unscaled),
('n points', u.dimensionless_unscaled)])
if (coords == 'KSM' or coords == 'KSO'):
self.units = OrderedDict([('Bx', u.nT), ('By', u.nT), ('Bz', u.nT),
('X', Rs), ('Y', Rs), ('Z', Rs),
('|B|', u.nT),
('Local hour', u.dimensionless_unscaled),
('n points', u.dimensionless_unscaled)])
def intervals(self, starttime, endtime):
return self.intervals_yearly(starttime, endtime)
def fname(self, interval):
year = interval.start.strftime('%Y')
return f'{year}_FGM_{self.coords}_1M.TAB'
def local_dir(self, interval):
return pathlib.Path('cassini') / 'mag' / '1min'
def download(self, interval):
local_dir = self.local_path(interval).parent
local_dir.mkdir(parents=True, exist_ok=True)
year = interval.start.strftime('%Y')
base_url = ('http://pds-ppi.igpp.ucla.edu/ditdos/download?'
'id=pds://PPI/CO-E_SW_J_S-MAG-4-SUMM-1MINAVG-V2.0/DATA')
url = '{}/{}'.format(base_url, year)
util._download_remote(url,
self.fname(interval),
local_dir)
def load_local_file(self, interval):
f = open(self.local_path(interval))
if 'error_message' in f.readline():
f.close()
os.remove(f.name)
raise util.NoDataError()
data = pd.read_csv(f,
names=['Time', 'Bx', 'By', 'Bz', '|B|',
'X', 'Y', 'Z', 'Local hour', 'n points'],
delim_whitespace=True,
parse_dates=[0], index_col=0)
f.close()
return data
def mag_1min(starttime, endtime, coords):
"""
Import 1 minute magnetic field from Cassini.
See http://pds-ppi.igpp.ucla.edu/search/view/?f=yes&id=pds://PPI/CO-E_SW_J_S-MAG-4-SUMM-1MINAVG-V1.0
for more information.
Cassini Orbiter Magnetometer Calibrated MAG data in 1 minute averages
available covering the period 1999-08-16 (DOY 228) to 2016-12-31 (DOY 366).
The data are provided in RTN coordinates throughout the mission, with
Earth, Jupiter, and Saturn centered coordinates for the respective
flybys of those planets.
Parameters
----------
starttime : datetime
Interval start time.
endtime : datetime
Interval end time.
coords : strings
Requested coordinate system. Must be one of
``['KRTP', 'KSM', 'KSO', 'RTN']``
Returns
-------
data : :class:`~sunpy.timeseries.TimeSeries`
Requested data
"""
dl = _mag1minDownloader(coords)
return dl.load(starttime, endtime)
def mag_hires(starttime, endtime, try_download=True):
"""
Import high resolution magnetic field from Cassini.
See http://pds-ppi.igpp.ucla.edu/search/view/?f=yes&id=pds://PPI/CO-E_SW_J_S-MAG-3-RDR-FULL-RES-V1.0
for more information.
Cassini Orbiter Magnetometer Calibrated MAG data at the highest time
resolution available covering the period 1999-08-16 (DOY 228) to
2016-12-31 (DOY 366).
The data are in RTN coordinates prior Cassini's arrival at Saturn, and
Kronographic (KRTP) coordinates at Saturn (beginning 2004-05-14, DOY 135).
Parameters
----------
starttime : datetime
Interval start time.
endtime : datetime
Interval end time.
Returns
-------
data : :class:`~sunpy.timeseries.TimeSeries`
Requested data
"""
remote_base_url = ('http://pds-ppi.igpp.ucla.edu/ditdos/download?id='
'pds://PPI/CO-E_SW_J_S-MAG-3-RDR-FULL-RES-V2.0/DATA')
dirs = []
fnames = []
extension = '.TAB'
units = OrderedDict([('Bx', u.nT), ('By', u.nT), ('Bz', u.nT),
('coords', u.dimensionless_unscaled)])
local_base_dir = cassini_dir / 'mag' / 'hires'
for [day, _, _] in util._daysplitinterval(starttime, endtime):
year = day.year
if calendar.isleap(year):
monthstr = leapmonth2str[day.month]
else:
monthstr = month2str[day.month]
if day < datetime.date(2004, 5, 14):
coords = 'RTN'
else:
coords = 'KRTP'
doy = day.strftime('%j')
dirs.append(pathlib.Path(str(year)) / monthstr)
fnames.append(str(year)[2:] + doy + '_FGM_{}'.format(coords))
def download_func(remote_base_url, local_base_dir,
directory, fname, remote_fname, extension):
url = remote_base_url + '/' + str(directory)
util._download_remote(url, fname + extension,
local_base_dir / directory)
def processing_func(f):
if 'error_message' in f.readline():
f.close()
os.remove(f.name)
raise util.NoDataError()
df = pd.read_csv(f, names=['Time', 'Bx', 'By', 'Bz'],
delim_whitespace=True,
parse_dates=[0], index_col=0)
return df
return util.process(dirs, fnames, extension, local_base_dir,
remote_base_url, download_func, processing_func,
starttime, endtime, units=units,
try_download=try_download)
