"""Class for reading and writing uvfits files.""" from astropy import constants as const import astropy from astropy.time import Time from astropy.io import fits import numpy as np import warnings from uvdata import UVData import parameter as uvp import utils as uvutils class UVFITS(UVData): """ Defines a uvfits-specific subclass of UVData for reading and writing uvfits files. This class should not be interacted with directly, instead use the read_uvfits and write_uvfits methods on the UVData class. Attributes: uvfits_required_extra: Names of optional UVParameters that are required for uvfits. """ uvfits_required_extra = ['antenna_positions', 'gst0', 'rdate', 'earth_omega', 'dut1', 'timesys'] def read_uvfits(self, filename, run_check=True, check_extra=True, run_check_acceptability=True): """ Read in data from a uvfits file. Args: filename: The uvfits file to read from. run_check: Option to check for the existence and proper shapes of parameters after reading in the file. Default is True. check_extra: Option to check optional parameters as well as required ones. Default is True. run_check_acceptability: Option to check acceptable range of the values of parameters after reading in the file. Default is True. """ F = fits.open(filename) D = F[0] # assumes the visibilities are in the primary hdu hdr = D.header.copy() hdunames = uvutils.fits_indexhdus(F) # find the rest of the tables # astropy.io fits reader scales date according to relevant PZER0 (?) time0_array = D.data['DATE'] try: # uvfits standard is to have 2 DATE parameters, both floats: # DATE (full day) and _DATE (fractional day) time1_array = D.data['_DATE'] self.time_array = (time0_array.astype(np.double) + time1_array.astype(np.double)) except(KeyError): # cotter uvfits files have one DATE that is a double self.time_array = time0_array if np.finfo(time0_array[0]).precision < 5: raise ValueError('JDs in this file are not precise to ' 'better than a second.') if (np.finfo(time0_array[0]).precision > 5 and np.finfo(time0_array[0]).precision < 8): warnings.warn('The JDs in this file have sub-second ' 'precision, but not sub-millisecond. ' 'Use with caution.') self.Ntimes = len(np.unique(self.time_array)) # if antenna arrays are present, use them. otherwise use baseline array try: # Note: uvfits antennas are 1 indexed, # need to subtract one to get to 0-indexed self.ant_1_array = np.int32(D.data.field('ANTENNA1')) - 1 self.ant_2_array = np.int32(D.data.field('ANTENNA2')) - 1 subarray = np.int32(D.data.field('SUBARRAY')) - 1 # error on files with multiple subarrays if len(set(subarray)) > 1: raise ValueError('This file appears to have multiple subarray ' 'values; only files with one subarray are ' 'supported.') except(KeyError): # cannot set this to be the baseline array because it uses the # 256 convention, not our 2048 convention bl_input_array = np.int64(D.data.field('BASELINE')) # get antenna arrays based on uvfits baseline array self.ant_1_array, self.ant_2_array = \ self.baseline_to_antnums(bl_input_array) # check for multi source files try: source = D.data.field('SOURCE') if len(set(source)) > 1: raise ValueError('This file has multiple sources. Only single ' 'source observations are supported.') except(KeyError): pass # get self.baseline_array using our convention self.baseline_array = \ self.antnums_to_baseline(self.ant_1_array, self.ant_2_array) self.Nbls = len(np.unique(self.baseline_array)) # initialize internal variables based on the antenna lists self.Nants_data = int( len(np.unique(self.ant_1_array.tolist() + self.ant_2_array.tolist()))) self.set_phased() # check if we have an spw dimension if hdr.pop('NAXIS') == 7: if hdr['NAXIS5'] > 1: raise ValueError('Sorry. Files with more than one spectral' + 'window (spw) are not yet supported. A ' + 'great project for the interested student!') self.data_array = (D.data.field('DATA')[:, 0, 0, :, :, :, 0] + 1j * D.data.field('DATA')[:, 0, 0, :, :, :, 1]) self.flag_array = (D.data.field('DATA')[:, 0, 0, :, :, :, 2] <= 0) self.nsample_array = np.abs( D.data.field('DATA')[:, 0, 0, :, :, :, 2]) self.Nspws = hdr.pop('NAXIS5') assert(self.Nspws == self.data_array.shape[1]) # the axis number for phase center depends on if the spw exists # subtract 1 to be zero-indexed self.spw_array = np.int32(uvutils.fits_gethduaxis(D, 5)) - 1 self.phase_center_ra_degrees = np.float(hdr.pop('CRVAL6')) self.phase_center_dec_degrees = np.float(hdr.pop('CRVAL7')) else: # in many uvfits files the spw axis is left out, # here we put it back in so the dimensionality stays the same self.data_array = (D.data.field('DATA')[:, 0, 0, :, :, 0] + 1j * D.data.field('DATA')[:, 0, 0, :, :, 1]) self.data_array = self.data_array[:, np.newaxis, :, :] self.flag_array = (D.data.field('DATA')[:, 0, 0, :, :, 2] <= 0) self.flag_array = self.flag_array[:, np.newaxis, :, :] self.nsample_array = np.abs(D.data.field('DATA')[:, 0, 0, :, :, 2]) self.nsample_array = (self.nsample_array[:, np.newaxis, :, :]) # the axis number for phase center depends on if the spw exists self.Nspws = 1 self.spw_array = np.array([0]) self.phase_center_ra_degrees = np.float(hdr.pop('CRVAL5')) self.phase_center_dec_degrees = np.float(hdr.pop('CRVAL6')) # get shapes self.Nfreqs = hdr.pop('NAXIS4') self.Npols = hdr.pop('NAXIS3') self.Nblts = hdr.pop('GCOUNT') # read baseline vectors in units of seconds, return in meters self.uvw_array = (np.array(np.stack((D.data.field('UU'), D.data.field('VV'), D.data.field('WW')))) * const.c.to('m/s').value).T self.freq_array = uvutils.fits_gethduaxis(D, 4) self.channel_width = hdr.pop('CDELT4') try: self.integration_time = float(D.data.field('INTTIM')[0]) except(KeyError): if self.Ntimes > 1: self.integration_time = \ float(np.diff(np.sort(list(set(self.time_array)))) [0]) * 86400 else: raise ValueError('integration time not specified and only ' 'one time present') self.freq_array.shape = (self.Nspws,) + self.freq_array.shape self.polarization_array = np.int32(uvutils.fits_gethduaxis(D, 3)) # other info -- not required but frequently used self.object_name = hdr.pop('OBJECT', None) self.telescope_name = hdr.pop('TELESCOP', None) self.instrument = hdr.pop('INSTRUME', None) latitude_degrees = hdr.pop('LAT', None) longitude_degrees = hdr.pop('LON', None) altitude = hdr.pop('ALT', None) self.x_orientation = hdr.pop('XORIENT', None) self.history = str(hdr.get('HISTORY', '')) if not uvutils.check_history_version(self.history, self.pyuvdata_version_str): self.history += self.pyuvdata_version_str while 'HISTORY' in hdr.keys(): hdr.remove('HISTORY') # if 'CASAHIST' in hdr.keys(): # self.casa_history=hdr.pop('CASAHIST',None) self.vis_units = hdr.pop('BUNIT', 'UNCALIB') self.phase_center_epoch = hdr.pop('EPOCH', None) # remove standard FITS header items that are still around std_fits_substrings = ['SIMPLE', 'BITPIX', 'EXTEND', 'BLOCKED', 'GROUPS', 'PCOUNT', 'BSCALE', 'BZERO', 'NAXIS', 'PTYPE', 'PSCAL', 'PZERO', 'CTYPE', 'CRVAL', 'CRPIX', 'CDELT', 'CROTA', 'CUNIT', 'DATE-OBS'] for key in hdr.keys(): for sub in std_fits_substrings: if key.find(sub) > -1: hdr.remove(key) # find all the remaining header items and keep them as extra_keywords for key in hdr: if key == '': continue if key == 'COMMENT': self.extra_keywords[key] = str(hdr.get(key)) else: self.extra_keywords[key] = hdr.get(key) # READ the antenna table ant_hdu = F[hdunames['AIPS AN']] # stuff in the header if self.telescope_name is None: self.telescope_name = ant_hdu.header['ARRNAM'] self.gst0 = ant_hdu.header['GSTIA0'] self.rdate = ant_hdu.header['RDATE'] self.earth_omega = ant_hdu.header['DEGPDY'] self.dut1 = ant_hdu.header['UT1UTC'] try: self.timesys = ant_hdu.header['TIMESYS'] except(KeyError): # CASA misspells this one self.timesys = ant_hdu.header['TIMSYS'] try: xyz_telescope_frame = ant_hdu.header['FRAME'] except(KeyError): warnings.warn('Required Antenna frame keyword not set, ' 'setting to ????') xyz_telescope_frame = '????' # get telescope location and antenna positions. # VLA incorrectly sets ARRAYX/ARRAYY/ARRAYZ to 0, and puts array center # in the antenna positions themselves if (np.isclose(ant_hdu.header['ARRAYX'], 0) and np.isclose(ant_hdu.header['ARRAYY'], 0) and np.isclose(ant_hdu.header['ARRAYZ'], 0)): x_telescope = np.mean(ant_hdu.data['STABXYZ'][:, 0]) y_telescope = np.mean(ant_hdu.data['STABXYZ'][:, 1]) z_telescope = np.mean(ant_hdu.data['STABXYZ'][:, 2]) self.antenna_positions = (ant_hdu.data.field('STABXYZ') - np.array([x_telescope, y_telescope, z_telescope])) else: x_telescope = ant_hdu.header['ARRAYX'] y_telescope = ant_hdu.header['ARRAYY'] z_telescope = ant_hdu.header['ARRAYZ'] # AIPS memo #117 says that antenna_positions should be relative to # the array center, but in a rotated ECEF frame so that the x-axis # goes through the local meridian. rot_ecef_positions = ant_hdu.data.field('STABXYZ') latitude, longitude, altitude = \ uvutils.LatLonAlt_from_XYZ(np.array([x_telescope, y_telescope, z_telescope])) self.antenna_positions = uvutils.ECEF_from_rotECEF(rot_ecef_positions, longitude) if xyz_telescope_frame == 'ITRF': self.telescope_location = np.array( [x_telescope, y_telescope, z_telescope]) else: if latitude_degrees is not None and longitude_degrees is not None and altitude is not None: self.telescope_location_lat_lon_alt_degrees = ( latitude_degrees, longitude_degrees, altitude) # stuff in columns ant_names = ant_hdu.data.field('ANNAME').tolist() self.antenna_names = [] for name in ant_names: self.antenna_names.append(name.replace('\x00!', '')) # subtract one to get to 0-indexed values rather than 1-indexed values self.antenna_numbers = ant_hdu.data.field('NOSTA') - 1 self.Nants_telescope = len(self.antenna_numbers) try: self.antenna_diameters = ant_hdu.data.field('DIAMETER') except(KeyError): pass del(D) try: self.set_telescope_params() except ValueError, ve: warnings.warn(str(ve)) self.set_lsts_from_time_array() # check if object has all required UVParameters set if run_check: self.check(check_extra=check_extra, run_check_acceptability=run_check_acceptability) def write_uvfits(self, filename, spoof_nonessential=False, force_phase=False, run_check=True, check_extra=True, run_check_acceptability=True): """ Write the data to a uvfits file. Args: filename: The uvfits file to write to. spoof_nonessential: Option to spoof the values of optional UVParameters that are not set but are required for uvfits files. Default is False. force_phase: Option to automatically phase drift scan data to zenith of the first timestamp. Default is False. run_check: Option to check for the existence and proper shapes of parameters before writing the file. Default is True. check_extra: Option to check optional parameters as well as required ones. Default is True. run_check_acceptability: Option to check acceptable range of the values of parameters before writing the file. Default is True. """ if run_check: self.check(check_extra=check_extra, run_check_acceptability=run_check_acceptability) if self.phase_type == 'phased': pass elif self.phase_type == 'drift': if force_phase: print('The data are in drift mode and do not have a ' 'defined phase center. Phasing to zenith of the first ' 'timestamp.') self.phase_to_time(self.time_array[0]) else: raise ValueError('The data are in drift mode. ' + 'Set force_phase to true to phase the data ' + 'to zenith of the first timestamp before ' + 'writing a uvfits file.') else: raise ValueError('The phasing type of the data is unknown. ' 'Set the phase_type to drift or phased to ' 'reflect the phasing status of the data') if self.Nfreqs > 1: freq_spacing = self.freq_array[0, 1:] - self.freq_array[0, :-1] if not np.isclose(np.min(freq_spacing), np.max(freq_spacing), rtol=self._freq_array.tols[0], atol=self._freq_array.tols[1]): raise ValueError('The frequencies are not evenly spaced (probably ' 'because of a select operation). The uvfits format ' 'does not support unevenly spaced frequencies.') if not np.isclose(freq_spacing[0], self.channel_width, rtol=self._freq_array.tols[0], atol=self._freq_array.tols[1]): raise ValueError('The frequencies are separated by more than their ' 'channel width (probably because of a select operation). ' 'The uvfits format does not support frequencies ' 'that are spaced by more than their channel width.') freq_spacing = freq_spacing[0] else: freq_spacing = 1 if self.Npols > 1: pol_spacing = np.diff(self.polarization_array) if np.min(pol_spacing) < np.max(pol_spacing): raise ValueError('The polarization values are not evenly spaced (probably ' 'because of a select operation). The uvfits format ' 'does not support unevenly spaced polarizations.') pol_spacing = pol_spacing[0] else: pol_spacing = 1 for p in self.extra(): param = getattr(self, p) if param.name in self.uvfits_required_extra: if param.value is None: if spoof_nonessential: # spoof extra keywords required for uvfits if isinstance(param, uvp.AntPositionParameter): param.apply_spoof(self, 'Nants_telescope') else: param.apply_spoof() setattr(self, p, param) else: raise ValueError('Required attribute {attribute} ' 'for uvfits not defined. Define or ' 'set spoof_nonessential to True to ' 'spoof this attribute.' .format(attribute=p)) weights_array = self.nsample_array * \ np.where(self.flag_array, -1, 1) data_array = self.data_array[:, np.newaxis, np.newaxis, :, :, :, np.newaxis] weights_array = weights_array[:, np.newaxis, np.newaxis, :, :, :, np.newaxis] # uvfits_array_data shape will be (Nblts,1,1,[Nspws],Nfreqs,Npols,3) uvfits_array_data = np.concatenate([data_array.real, data_array.imag, weights_array], axis=6) uvw_array_sec = self.uvw_array / const.c.to('m/s').value # jd_midnight = np.floor(self.time_array[0] - 0.5) + 0.5 tzero = np.float32(self.time_array[0]) # uvfits convention is that time_array + relevant PZERO = actual JD # We are setting PZERO4 = float32(first time of observation) time_array = np.float32(self.time_array - np.float64(tzero)) int_time_array = (np.zeros_like((time_array), dtype=np.float) + self.integration_time) baselines_use = self.antnums_to_baseline(self.ant_1_array, self.ant_2_array, attempt256=True) # Set up dictionaries for populating hdu # Note that uvfits antenna arrays are 1-indexed so we add 1 # to our 0-indexed arrays group_parameter_dict = {'UU ': uvw_array_sec[:, 0], 'VV ': uvw_array_sec[:, 1], 'WW ': uvw_array_sec[:, 2], 'DATE ': time_array, 'BASELINE': baselines_use, 'ANTENNA1': self.ant_1_array + 1, 'ANTENNA2': self.ant_2_array + 1, 'SUBARRAY': np.ones_like(self.ant_1_array), 'INTTIM': int_time_array} pscal_dict = {'UU ': 1.0, 'VV ': 1.0, 'WW ': 1.0, 'DATE ': 1.0, 'BASELINE': 1.0, 'ANTENNA1': 1.0, 'ANTENNA2': 1.0, 'SUBARRAY': 1.0, 'INTTIM': 1.0} pzero_dict = {'UU ': 0.0, 'VV ': 0.0, 'WW ': 0.0, 'DATE ': tzero, 'BASELINE': 0.0, 'ANTENNA1': 0.0, 'ANTENNA2': 0.0, 'SUBARRAY': 0.0, 'INTTIM': 0.0} # list contains arrays of [u,v,w,date,baseline]; # each array has shape (Nblts) if (np.max(self.ant_1_array) < 255 and np.max(self.ant_2_array) < 255): # if the number of antennas is less than 256 then include both the # baseline array and the antenna arrays in the group parameters. # Otherwise just use the antenna arrays parnames_use = ['UU ', 'VV ', 'WW ', 'DATE ', 'BASELINE', 'ANTENNA1', 'ANTENNA2', 'SUBARRAY', 'INTTIM'] else: parnames_use = ['UU ', 'VV ', 'WW ', 'DATE ', 'ANTENNA1', 'ANTENNA2', 'SUBARRAY', 'INTTIM'] group_parameter_list = [group_parameter_dict[parname] for parname in parnames_use] hdu = fits.GroupData(uvfits_array_data, parnames=parnames_use, pardata=group_parameter_list, bitpix=-32) hdu = fits.GroupsHDU(hdu) for i, key in enumerate(parnames_use): hdu.header['PSCAL' + str(i + 1) + ' '] = pscal_dict[key] hdu.header['PZERO' + str(i + 1) + ' '] = pzero_dict[key] # ISO string of first time in self.time_array hdu.header['DATE-OBS'] = Time(self.time_array[0], scale='utc', format='jd').isot hdu.header['CTYPE2 '] = 'COMPLEX ' hdu.header['CRVAL2 '] = 1.0 hdu.header['CRPIX2 '] = 1.0 hdu.header['CDELT2 '] = 1.0 hdu.header['CTYPE3 '] = 'STOKES ' hdu.header['CRVAL3 '] = self.polarization_array[0] hdu.header['CRPIX3 '] = 1.0 hdu.header['CDELT3 '] = pol_spacing hdu.header['CTYPE4 '] = 'FREQ ' hdu.header['CRVAL4 '] = self.freq_array[0, 0] hdu.header['CRPIX4 '] = 1.0 hdu.header['CDELT4 '] = freq_spacing hdu.header['CTYPE5 '] = 'IF ' hdu.header['CRVAL5 '] = 1.0 hdu.header['CRPIX5 '] = 1.0 hdu.header['CDELT5 '] = 1.0 hdu.header['CTYPE6 '] = 'RA' hdu.header['CRVAL6 '] = self.phase_center_ra_degrees hdu.header['CTYPE7 '] = 'DEC' hdu.header['CRVAL7 '] = self.phase_center_dec_degrees hdu.header['BUNIT '] = self.vis_units hdu.header['BSCALE '] = 1.0 hdu.header['BZERO '] = 0.0 hdu.header['OBJECT '] = self.object_name hdu.header['TELESCOP'] = self.telescope_name hdu.header['LAT '] = self.telescope_location_lat_lon_alt_degrees[0] hdu.header['LON '] = self.telescope_location_lat_lon_alt_degrees[1] hdu.header['ALT '] = self.telescope_location_lat_lon_alt[2] hdu.header['INSTRUME'] = self.instrument hdu.header['EPOCH '] = float(self.phase_center_epoch) if self.x_orientation is not None: hdu.header['XORIENT'] = self.x_orientation for line in self.history.splitlines(): hdu.header.add_history(line) # end standard keywords; begin user-defined keywords for key, value in self.extra_keywords.iteritems(): # header keywords have to be 8 characters or less if len(str(key)) > 8: warnings.warn('key {key} in extra_keywords is longer than 8 ' 'characters. It will be truncated to 8 as required ' 'by the uvfits file format.'.format(key=key)) keyword = key[:8].upper() if isinstance(value, (dict, list, np.ndarray)): raise TypeError('Extra keyword {keyword} is of {keytype}. ' 'Only strings and numbers are ' 'supported in uvfits.'.format(keyword=key, keytype=type(value))) # print "keyword=-value-", keyword+'='+'-'+str(value)+'-' if keyword == 'COMMENT': for line in value.splitlines(): hdu.header.add_comment(line) else: hdu.header[keyword] = value # ADD the ANTENNA table staxof = np.zeros(self.Nants_telescope) # 0 specifies alt-az, 6 would specify a phased array mntsta = np.zeros(self.Nants_telescope) # beware, X can mean just about anything poltya = np.full((self.Nants_telescope), 'X', dtype=np.object_) polaa = [90.0] + np.zeros(self.Nants_telescope) poltyb = np.full((self.Nants_telescope), 'Y', dtype=np.object_) polab = [0.0] + np.zeros(self.Nants_telescope) col1 = fits.Column(name='ANNAME', format='8A', array=self.antenna_names) # AIPS memo #117 says that antenna_positions should be relative to # the array center, but in a rotated ECEF frame so that the x-axis # goes through the local meridian. longitude = self.telescope_location_lat_lon_alt[1] rot_ecef_positions = uvutils.rotECEF_from_ECEF(self.antenna_positions, longitude) col2 = fits.Column(name='STABXYZ', format='3D', array=rot_ecef_positions) # convert to 1-indexed from 0-indexed indicies col3 = fits.Column(name='NOSTA', format='1J', array=self.antenna_numbers + 1) col4 = fits.Column(name='MNTSTA', format='1J', array=mntsta) col5 = fits.Column(name='STAXOF', format='1E', array=staxof) col6 = fits.Column(name='POLTYA', format='1A', array=poltya) col7 = fits.Column(name='POLAA', format='1E', array=polaa) # col8 = fits.Column(name='POLCALA', format='3E', array=polcala) col9 = fits.Column(name='POLTYB', format='1A', array=poltyb) col10 = fits.Column(name='POLAB', format='1E', array=polab) # col11 = fits.Column(name='POLCALB', format='3E', array=polcalb) # note ORBPARM is technically required, but we didn't put it in col_list = [col1, col2, col3, col4, col5, col6, col7, col9, col10] if self.antenna_diameters is not None: col12 = fits.Column(name='DIAMETER', format='1E', array=self.antenna_diameters) col_list.append(col12) cols = fits.ColDefs(col_list) ant_hdu = fits.BinTableHDU.from_columns(cols) ant_hdu.header['EXTNAME'] = 'AIPS AN' ant_hdu.header['EXTVER'] = 1 # write XYZ coordinates if not already defined ant_hdu.header['ARRAYX'] = self.telescope_location[0] ant_hdu.header['ARRAYY'] = self.telescope_location[1] ant_hdu.header['ARRAYZ'] = self.telescope_location[2] ant_hdu.header['FRAME'] = 'ITRF' ant_hdu.header['GSTIA0'] = self.gst0 ant_hdu.header['FREQ'] = self.freq_array[0, 0] ant_hdu.header['RDATE'] = self.rdate ant_hdu.header['UT1UTC'] = self.dut1 ant_hdu.header['TIMSYS'] = self.timesys if self.timesys != 'UTC': raise ValueError('This file has a time system {tsys}. ' 'Only "UTC" time system files are supported'.format(tsys=self.timesys)) ant_hdu.header['ARRNAM'] = self.telescope_name ant_hdu.header['NO_IF'] = self.Nspws ant_hdu.header['DEGPDY'] = self.earth_omega # ant_hdu.header['IATUTC'] = 35. # set mandatory parameters which are not supported by this object # (or that we just don't understand) ant_hdu.header['NUMORB'] = 0 # note: Bart had this set to 3. We've set it 0 after aips 117. -jph ant_hdu.header['NOPCAL'] = 0 ant_hdu.header['POLTYPE'] = 'X-Y LIN' # note: we do not support the concept of "frequency setups" # -- lists of spws given in a SU table. ant_hdu.header['FREQID'] = -1 # if there are offsets in images, this could be the culprit ant_hdu.header['POLARX'] = 0.0 ant_hdu.header['POLARY'] = 0.0 ant_hdu.header['DATUTC'] = 0 # ONLY UTC SUPPORTED # we always output right handed coordinates ant_hdu.header['XYZHAND'] = 'RIGHT' # ADD the FQ table # skipping for now and limiting to a single spw # write the file hdulist = fits.HDUList(hdus=[hdu, ant_hdu]) if float(astropy.__version__[0:3]) < 1.3: hdulist.writeto(filename, clobber=True) else: hdulist.writeto(filename, overwrite=True)