def geometric_delay(baselines, skypos, altaz=False, dircos=False, hadec=True,
units='mks', latitude=None):
"""
---------------------------------------------------------------------
Estimates the geometric delays matrix for different baselines from
different sky positions.
Inputs:
baselines: x, y, and z components of baseline vectors in a Mx3 numpy
array
skypos: Nx2 (Alt-Az or HA-Dec) or Nx3 (direction cosines) numpy array
of sky positions
altaz: [Boolean flag, default=False] If True, skypos is in Alt-Az
coordinates system
hadec: [Boolean flag, default=True] If True, skypos is in HA-Dec
coordinates system
dircos: [Boolean flag, default=False] If True, skypos is in direction
cosines coordinates system
units: Units of baselines. Default='mks'. Alternative is 'cgs'.
latitude: Latitude of the observatory. Required if hadec is True.
Outputs:
geometric delays [NxM numpy array] Geometric delay for every combination
of baselines and skypos.
---------------------------------------------------------------------
"""
try:
baselines, skypos
except NameError:
raise NameError('baselines and/or skypos not defined in geometric_delay().')
if (altaz)+(dircos)+(hadec) != 1:
raise ValueError('One and only one of altaz, dircos, hadec must be set to True.')
if hadec and (latitude is None):
raise ValueError('Latitude must be specified when skypos is in HA-Dec format.')
try:
units
except NameError:
print 'No units provided. Assuming MKS units.'
units = 'mks'
if (units != 'mks') and (units != 'cgs'):
print 'Units should be specified to be one of MKS or CGS. Default=MKS'
print 'Proceeding with MKS units.'
units = 'mks'
if not isinstance(baselines, NP.ndarray):
raise TypeError('baselines should be a Nx3 numpy array in geometric_delay().')
if len(baselines.shape) == 1:
baselines = baselines.reshape(1,-1)
if baselines.shape[1] == 1:
baselines = NP.hstack(baselines, NP.zeros((baselines.size,2)))
elif baselines.shape[1] == 2:
baselines = NP.hstack(baselines, NP.zeros((baselines.size,1)))
elif baselines.shape[1] > 3:
baselines = baselines[:,:3]
if altaz or hadec:
if len(skypos.shape) < 2:
if skypos.size != 2:
raise ValueError('Sky position in altitude-azimuth or HA-Dec should consist of 2 elements.')
else:
skypos = skypos.reshape(1,-1)
elif len(skypos.shape) > 2:
raise ValueError('Sky positions should be a Nx2 numpy array if using altitude-azimuth of HA-Dec.')
else:
if skypos.shape[1] != 2:
raise ValueError('Sky positions should be a Nx2 numpy array if using altitude-azimuth of HA-Dec.')
if altaz:
dc = GEOM.altaz2dircos(skypos, 'degrees')
else:
dc = GEOM.altaz2dircos(GEOM.hadec2altaz(skypos, latitude, 'degrees'), 'degrees')
else:
if len(skypos.shape) < 2:
if skypos.size != 3:
raise ValueError('Sky position in direction cosines should consist of 3 elements.')
else:
skypos = skypos.reshape(1,-1)
elif len(skypos.shape) > 2:
raise ValueError('Sky positions should be a Nx3 numpy array if using direction cosines.')
else:
if skypos.shape[1] != 3:
raise ValueError('Sky positions should be a Nx3 numpy array if using direction cosines.')
dc = skypos
# geometric_delays = delay_envelope(baselines, dc, units)[:,:,-1]
geometric_delays = NP.dot(dc, baselines.T)/c
return geometric_delays
# pfb_interp_func = interpolate.interp1d(pfbfreq[useful_freq_range]/1e3, pfbwin[useful_freq_range])
# pfbwin_interp = pfb_interp_func(chans)
pfbwin_interp = NP.interp(chans, pfbfreq[useful_freq_range]/1e3, pfbwin[useful_freq_range])
bandpass_shape = 10**(pfbwin_interp/10)
window = n_channels * DSP.windowing(n_channels, shape=bpass_shape, pad_width=n_pad, centering=True, area_normalize=True)
bpass = base_bpass * bandpass_shape
n_snaps = int(t_obs/t_snap)
lst = (lst_init + (t_snap/3.6e3) * NP.arange(n_snaps)) * 15.0 # in degrees
if obs_mode == 'track':
pointings_radec = NP.repeat(NP.asarray(pointing_init).reshape(-1,2), n_snaps, axis=0)
else:
pointings_radec = NP.hstack((NP.asarray(lst-pointing_init[0]).reshape(-1,1), pointing_init[1]+NP.zeros(n_snaps).reshape(-1,1)))
pointings_hadec = NP.hstack(((lst-pointings_radec[:,0]).reshape(-1,1), pointings_radec[:,1].reshape(-1,1)))
pointings_altaz = GEOM.hadec2altaz(pointings_hadec, latitude, units='degrees')
pointings_dircos = GEOM.altaz2dircos(pointings_altaz, units='degrees')
## Interferometer parameters
# baseline_orientation = NP.asarray([0.0, 90.0]) # in degrees from East towards North
# baseline_length = 1000.0 + NP.zeros(2) # in m
# baseline_vect = NP.zeros((2,3))
# baseline_vect[:,0] = baseline_length * NP.cos(NP.radians(baseline_orientation))
# baseline_vect[:,1] = baseline_length * NP.sin(NP.radians(baseline_orientation))
# baseline_orientation_str = '{0:.1f}'.format(baseline_orientation)
# baseline_length_str = '{0:.1f}'.format(baseline_length)
# ia = RI.InterferometerArray(labels, bl, chans, telescope=telescope, latitude=latitude, A_eff=A_eff, freq_scale='GHz')
# # ia = RI.InterferometerArray(['B1','B2'], baseline_vect, chans, telescope=telescope, latitude=latitude, A_eff=A_eff, freq_scale='GHz')
bandpass_shape[flagged_channels] = 0.0
n_snaps = int(1.0 * t_obs / t_snap)
lst = (lst_init + (t_snap / 3.6e3) * NP.arange(n_snaps)) * 15.0 # in degrees
if obs_mode == 'track':
pointings_radec = NP.repeat(NP.asarray(pointing_init).reshape(-1, 2),
n_snaps,
axis=0)
else:
pointings_radec = NP.hstack(
(NP.asarray(lst - pointing_init[0]).reshape(-1, 1),
pointing_init[1] + NP.zeros(n_snaps).reshape(-1, 1)))
pointings_hadec = NP.hstack(((lst - pointings_radec[:, 0]).reshape(-1, 1),
pointings_radec[:, 1].reshape(-1, 1)))
pointings_altaz = GEOM.hadec2altaz(pointings_hadec, latitude, units='degrees')
pointings_dircos = GEOM.altaz2dircos(pointings_altaz, units='degrees')
use_GSM = args['ASM']
use_DSM = args['DSM']
use_NVSS = args['NVSS']
use_SUMSS = args['SUMSS']
use_MSS = args['MSS']
use_GLEAM = args['GLEAM']
use_PS = args['PS']
fg_str = ''
nside = args['nside']
flux_unit = args['flux_unit']
if use_GSM:
hdulist = fits.open(infile+'.fits')
latitude = hdulist[0].header['latitude']
pointing_coords = hdulist[0].header['pointing_coords']
pointings_table = hdulist['POINTING AND PHASE CENTER INFO'].data
lst = pointings_table['LST']
n_snaps = lst.size
hdulist.close()
if pointing_coords == 'altaz':
pointings_altaz = NP.hstack((pointings_table['pointing_latitude'].reshape(-1,1), pointings_table['pointing_longitude'].reshape(-1,1)))
pointings_hadec = GEOM.altaz2hadec(pointings_altaz, latitude, units='degrees')
pointings_dircos = GEOM.altaz2dircos(pointings_altaz, units='degrees')
elif pointing_coords == 'radec':
pointings_radec = NP.hstack((pointings_table['pointing_longitude'].reshape(-1,1), pointings_table['pointing_latitude'].reshape(-1,1)))
pointings_hadec = NP.hstack(((lst-pointings_radec[:,0]).reshape(-1,1), pointings_radec[:,1].reshape(-1,1)))
pointings_altaz = GEOM.hadec2altaz(pointings_hadec, latitude, units='degrees')
pointings_dircos = GEOM.altaz2dircos(pointings_altaz, units='degrees')
elif pointing_coords == 'hadec':
pointings_hadec = NP.hstack((pointings_table['pointing_longitude'].reshape(-1,1), pointings_table['pointing_latitude'].reshape(-1,1)))
pointings_radec = NP.hstack(((lst-pointings_hadec[:,0]).reshape(-1,1), pointings_hadec[:,1].reshape(-1,1)))
pointings_altaz = GEOM.hadec2altaz(pointings_hadec, latitude, units='degrees')
pointings_dircos = GEOM.altaz2dircos(pointings_altaz, units='degrees')
hdulist = fits.open(asm_CLEAN_infile+'.fits')
clean_lags = hdulist['SPECTRAL INFO'].data['lag']
clean_lags_orig = NP.copy(clean_lags)
asm_cc_skyvis = hdulist['CLEAN NOISELESS VISIBILITIES REAL'].data + 1j * hdulist['CLEAN NOISELESS VISIBILITIES IMAG'].data
asm_cc_skyvis_res = hdulist['CLEAN NOISELESS VISIBILITIES RESIDUALS REAL'].data + 1j * hdulist['CLEAN NOISELESS VISIBILITIES RESIDUALS IMAG'].data
asm_cc_vis = hdulist['CLEAN NOISY VISIBILITIES REAL'].data + 1j * hdulist['CLEAN NOISY VISIBILITIES IMAG'].data
asm_cc_vis_res = hdulist['CLEAN NOISY VISIBILITIES RESIDUALS REAL'].data + 1j * hdulist['CLEAN NOISY VISIBILITIES RESIDUALS IMAG'].data
hdulist.close()
obs_mode = 'track'
if obs_mode == 'track':
pointings_radec = NP.repeat(NP.asarray(pointing_init).reshape(-1, 2),
n_snaps,
axis=0)
else:
ha_init = lst_init * 15.0 - pointing_init[0]
pointings_radec = NP.hstack(
(NP.asarray(lst - ha_init).reshape(-1, 1),
pointing_init[1] + NP.zeros(n_snaps).reshape(-1, 1)))
pointings_hadec = NP.hstack(((lst - pointings_radec[:, 0]).reshape(-1, 1),
pointings_radec[:, 1].reshape(-1, 1)))
pointings_altaz = GEOM.hadec2altaz(pointings_hadec,
latitude,
units='degrees')
pointings_dircos = GEOM.altaz2dircos(pointings_altaz, units='degrees')
pointings_radec_orig = NP.copy(pointings_radec)
pointings_hadec_orig = NP.copy(pointings_hadec)
pointings_altaz_orig = NP.copy(pointings_altaz)
pointings_dircos_orig = NP.copy(pointings_dircos)
lst_wrapped = lst + 0.0
lst_wrapped[lst_wrapped > 180.0] = lst_wrapped[lst_wrapped > 180.0] - 360.0
if lst_wrapped.size > 1:
lst_edges = NP.concatenate(
(lst_wrapped,
[lst_wrapped[-1] + lst_wrapped[-1] - lst_wrapped[-2]]))
else:
ant_locs = NP.loadtxt(antenna_file, skiprows=6, comments='#', usecols=(1,2,3))
bl = RI.baseline_generator(ant_locs, auto=False, conjugate=False)
bl_lengths = NP.sqrt(NP.sum(bl**2,axis=1))
decl = -27.0 # in degrees
lat = -27.0 # in degrees
ha_range = 4.0 # in hrs
ha_step = 1.0/60. # in hrs
ha = 15.0*NP.arange(-ha_range/2, ha_range/2, ha_step)
ha = NP.asarray(ha).reshape(-1,1)
dec = decl + NP.zeros((len(ha),1))
dec.reshape(-1,1)
hadec = NP.hstack((ha, dec))
altaz = GEOM.hadec2altaz(hadec, lat, units='degrees')
dircos = GEOM.altaz2dircos(altaz, units='degrees')
dm = DLY.delay_envelope(bl, dircos, units='mks')
min_delays = dm[:,:,1]-dm[:,:,0]
max_delays = NP.sum(dm,axis=2)
fig = PLT.figure(figsize=(14,8))
ax = PLT.axes([0.12,0.1,0.8,0.8])
PLT.xlim(NP.min(bl_lengths)-1.0,NP.max(bl_lengths)+100.0)
PLT.ylim(1e9*(NP.min(min_delays)-1.e-8),1e9*(NP.max(max_delays)+1.e-8))
PLT.xlabel('Baseline Length [m]', fontsize=18, weight='semibold')
PLT.ylabel('Delay [ns]', fontsize=18, weight='semibold')
PLT.title('Delay Envelope', fontsize=18, weight='semibold')
def observe(
self, timestamp, Tsys, bandpass, pointing_center, skymodel, tobs, pb_min=0.1, fov_radius=None, lst=None
):
if bandpass.size != self.bp.shape[1]:
raise ValueError("bandpass length does not match.")
self.Tsys = self.Tsys + [Tsys]
self.vis_rms_freq = self.vis_rms_freq + [
2.0 * FCNST.k * Tsys / self.A_eff / self.eff_Q / NP.sqrt(2) / tobs / self.freq_resolution / CNST.Jy
]
self.tobs = self.tobs + [tobs]
self.lst = self.lst + [lst]
if self.timestamp == []:
self.bp = NP.asarray(bandpass).reshape(1, -1)
self.pointing_center = NP.asarray(pointing_center).reshape(1, -1)
else:
self.bp = NP.vstack((self.bp, NP.asarray(bandpass).reshape(1, -1)))
self.pointing_center = NP.vstack((self.pointing_center, NP.asarray(pointing_center).reshape(1, -1)))
pointing_lon = self.pointing_center[-1, 0]
pointing_lat = self.pointing_center[-1, 1]
if self.skycoords == "radec":
if self.pointing_coords == "hadec":
if lst is not None:
pointing_lon = lst - self.pointing_center[-1, 0]
pointing_lat = self.pointing_center[-1, 1]
else:
raise ValueError(
"LST must be provided. Sky coordinates are in RA-Dec format while pointing center is in HA-Dec format."
)
elif self.pointing_coords == "altaz":
pointing_lonlat = lst - GEOM.altaz2hadec(self.pointing_center[-1, :], self.latitude, units="degrees")
pointing_lon = pointing_lonlat[0]
pointing_lat = pointing_lonlat[1]
elif self.skycoords == "hadec":
if self.pointing_coords == "radec":
if lst is not None:
pointing_lon = lst - self.pointing_center[-1, 0]
pointing_lat = self.pointing_center[-1, 1]
else:
raise ValueError(
"LST must be provided. Sky coordinates are in RA-Dec format while pointing center is in HA-Dec format."
)
elif self.pointing_coords == "altaz":
pointing_lonlat = lst - GEOM.altaz2hadec(self.pointing_center[-1, :], self.latitude, units="degrees")
pointing_lon = pointing_lonlat[0]
pointing_lat = pointing_lonlat[1]
else:
if self.pointing_coords == "radec":
if lst is not None:
pointing_lonlat = GEOM.hadec2altaz(
NP.asarray([lst - self.pointing_center[-1, 0], self.pointing_center[-1, 1]]),
self.latitude,
units="degrees",
)
pointing_lon = pointing_lonlat[0]
pointing_lat = pointing_lonlat[1]
else:
raise ValueError(
"LST must be provided. Sky coordinates are in Alt-Az format while pointing center is in RA-Dec format."
)
elif self.pointing_coords == "hadec":
pointing_lonlat = GEOM.hadec2altaz(self.pointing_center, self.latitude, units="degrees")
pointing_lon = pointing_lonlat[0]
pointing_lat = pointing_lonlat[1]
pointing_phase = 0.0
baseline_in_local_frame = self.baseline
if self.baseline_coords == "equatorial":
baseline_in_local_frame = GEOM.xyz2enu(self.baseline, self.latitude, "degrees")
ptmp = self.pointing_center[-1, :] # Convert pointing center to Alt-Az coordinates
if self.pointing_coords == "hadec":
ptmp = GEOM.hadec2altaz(self.pointing_center[-1, :], self.latitude, units="degrees")
elif self.pointing_coords == "radec":
if lst is not None:
ptmp = GEOM.hadec2altaz(
NP.asarray([lst - self.pointing_center[-1, 0], self.pointing_center[-1, 1]]),
self.latitude,
units="degrees",
)
else:
raise ValueError(
"LST must be provided. Sky coordinates are in Alt-Az format while pointing center is in RA-Dec format."
)
ptmp = GEOM.altaz2dircos(ptmp, "degrees") # Convert pointing center to direction cosine coordinates
pointing_phase = (
2.0
* NP.pi
* NP.dot(baseline_in_local_frame.reshape(1, -1), ptmp.reshape(-1, 1))
* self.channels.reshape(1, -1)
/ FCNST.c
)
if fov_radius is None:
fov_radius = 90.0
# PDB.set_trace()
m1, m2, d12 = GEOM.spherematch(
pointing_lon,
pointing_lat,
skymodel.catalog.location[:, 0],
skymodel.catalog.location[:, 1],
fov_radius,
maxmatches=0,
)
# if fov_radius is not None:
# m1, m2, d12 = GEOM.spherematch(pointing_lon, pointing_lat, skymodel.catalog.location[:,0], skymodel.catalog.location[:,1], fov_radius, maxmatches=0)
# else:
# m1 = [0] * skymodel.catalog.location.shape[0]
# m2 = xrange(skymodel.catalog.location.shape[0])
# d12 = GEOM.sphdist(NP.empty(skymodel.catalog.shape[0]).fill(pointing_lon), NP.empty(skymodel.catalog.shape[0]).fill(pointing_lat), skymodel.catalog.location[:,0], skymodel.catalog.location[:,1])
if len(d12) != 0:
pb = NP.empty((len(d12), len(self.channels)))
fluxes = NP.empty((len(d12), len(self.channels)))
coords_str = self.skycoords
if self.skycoords == "radec":
coords_str = "altaz"
source_positions = GEOM.hadec2altaz(
NP.hstack(
(
NP.asarray(lst - skymodel.catalog.location[m2, 0]).reshape(-1, 1),
skymodel.catalog.location[m2, 1].reshape(-1, 1),
)
),
self.latitude,
"degrees",
)
for i in xrange(len(self.channels)):
# pb[:,i] = PB.primary_beam_generator(d12, self.channels[i]/1.0e9, 'degrees', self.telescope)
pb[:, i] = PB.primary_beam_generator(
source_positions, self.channels[i] / 1.0e9, "altaz", self.telescope
)
fluxes[:, i] = (
skymodel.catalog.flux_density[m2]
* (self.channels[i] / skymodel.catalog.frequency) ** skymodel.catalog.spectral_index[m2]
)
geometric_delays = DLY.geometric_delay(
baseline_in_local_frame,
source_positions,
altaz=(coords_str == "altaz"),
hadec=(coords_str == "hadec"),
latitude=self.latitude,
)
self.geometric_delays = self.geometric_delays + [geometric_delays.reshape(len(source_positions))]
phase_matrix = 2.0 * NP.pi * NP.repeat(
geometric_delays.reshape(-1, 1), len(self.channels), axis=1
) * NP.repeat(self.channels.reshape(1, -1), len(d12), axis=0) - NP.repeat(pointing_phase, len(d12), axis=0)
skyvis = NP.sum(
pb
* fluxes
* NP.repeat(NP.asarray(bandpass).reshape(1, -1), len(d12), axis=0)
* NP.exp(-1j * phase_matrix),
axis=0,
)
if fov_radius is not None:
self.obs_catalog_indices = self.obs_catalog_indices + [m2]
# self.obs_catalog = self.obs_catalog + [skymodel.catalog.subset(m2)]
else:
print "No sources found in the catalog within matching radius. Simply populating the observed visibilities with noise."
skyvis = NP.zeros((1, len(self.channels)))
if self.timestamp == []:
self.skyvis_freq = skyvis.reshape(1, -1)
self.vis_noise_freq = self.vis_rms_freq[-1] * (
NP.random.randn(len(self.channels)).reshape(1, -1)
+ 1j * NP.random.randn(len(self.channels)).reshape(1, -1)
)
self.vis_freq = self.skyvis_freq + self.vis_noise_freq
else:
self.skyvis_freq = NP.vstack((self.skyvis_freq, skyvis.reshape(1, -1)))
self.vis_noise_freq = NP.vstack(
(
self.vis_noise_freq,
self.vis_rms_freq[-1]
* (
NP.random.randn(len(self.channels)).reshape(1, -1)
+ 1j * NP.random.randn(len(self.channels)).reshape(1, -1)
),
)
)
self.vis_freq = NP.vstack(
(self.vis_freq, (self.skyvis_freq[-1, :] + self.vis_noise_freq[-1, :]).reshape(1, -1))
)
self.timestamp = self.timestamp + [timestamp]
n_snaps = int(t_obs/t_snap)
else:
t_obs = n_snaps * t_snap
t_snap = t_snap + NP.zeros(n_snaps)
lst = (lst_init + (t_snap/3.6e3) * NP.arange(n_snaps)) * 15.0 # in degrees
if obs_mode is None:
obs_mode = 'track'
if obs_mode == 'track':
pointings_radec = NP.repeat(NP.asarray(pointing_init).reshape(-1,2), n_snaps, axis=0)
else:
ha_init = lst_init * 15.0 - pointing_init[0]
pointings_radec = NP.hstack((NP.asarray(lst-ha_init).reshape(-1,1), pointing_init[1]+NP.zeros(n_snaps).reshape(-1,1)))
pointings_hadec = NP.hstack(((lst-pointings_radec[:,0]).reshape(-1,1), pointings_radec[:,1].reshape(-1,1)))
pointings_altaz = GEOM.hadec2altaz(pointings_hadec, latitude, units='degrees')
pointings_dircos = GEOM.altaz2dircos(pointings_altaz, units='degrees')
pointings_radec_orig = NP.copy(pointings_radec)
pointings_hadec_orig = NP.copy(pointings_hadec)
pointings_altaz_orig = NP.copy(pointings_altaz)
pointings_dircos_orig = NP.copy(pointings_dircos)
lst_wrapped = lst + 0.0
lst_wrapped[lst_wrapped > 180.0] = lst_wrapped[lst_wrapped > 180.0] - 360.0
if lst_wrapped.size > 1:
lst_edges = NP.concatenate((lst_wrapped, [lst_wrapped[-1]+lst_wrapped[-1]-lst_wrapped[-2]]))
else:
lst_edges = NP.concatenate((lst_wrapped, lst_wrapped+t_snap/3.6e3*15))
duration_str = '_{0:0d}x{1:.1f}s'.format(n_snaps, t_snap[0])
ant_locs = NP.loadtxt(antenna_file, skiprows=6, comments="#", usecols=(1, 2, 3))
bl = GEOM.baseline_generator(ant_locs, auto=False, conjugate=False)
bl_lengths = NP.sqrt(NP.sum(bl ** 2, axis=1))
decl = -27.0 # in degrees
lat = -27.0 # in degrees
ha_range = 4.0 # in hrs
ha_step = 1.0 / 60.0 # in hrs
ha = 15.0 * NP.arange(-ha_range / 2, ha_range / 2, ha_step)
ha = NP.asarray(ha).reshape(-1, 1)
dec = decl + NP.zeros((len(ha), 1))
dec.reshape(-1, 1)
hadec = NP.hstack((ha, dec))
altaz = GEOM.hadec2altaz(hadec, lat, units="degrees")
dircos = GEOM.altaz2dircos(altaz, units="degrees")
dm = DLY.delay_envelope(bl, dircos, units="mks")
min_delays = dm[:, :, 1] - dm[:, :, 0]
max_delays = NP.sum(dm, axis=2)
fig = PLT.figure(figsize=(14, 8))
ax = PLT.axes([0.12, 0.1, 0.8, 0.8])
PLT.xlim(NP.min(bl_lengths) - 1.0, NP.max(bl_lengths) + 100.0)
PLT.ylim(1e9 * (NP.min(min_delays) - 1.0e-8), 1e9 * (NP.max(max_delays) + 1.0e-8))
PLT.xlabel("Baseline Length [m]", fontsize=18, weight="semibold")
PLT.ylabel("Delay [ns]", fontsize=18, weight="semibold")
PLT.title("Delay Envelope", fontsize=18, weight="semibold")
## GSM and Power pattern animation data
gsm_cartesian = HP.cartview(fluxes.ravel(), coord=['G','E'], xsize=200, return_projected_map=True)
ragrid, decgrid = NP.meshgrid(NP.linspace(NP.amin(ra_deg), NP.amax(ra_deg), gsm_cartesian.shape[1]), NP.linspace(NP.amin(dec_deg), NP.amax(dec_deg), gsm_cartesian.shape[0]))
ravect = ragrid.ravel()
decvect = decgrid.ravel()
n_snaps = int(t_obs/t_snap)
lst = (lst_init + (t_snap/3.6e3) * NP.arange(n_snaps)) * 15.0 # in degrees
# Get pointings in RA-Dec coordinates for animation
if obs_mode == 'track':
pointings_radec = NP.repeat(NP.asarray(pointing_init).reshape(-1,2), n_snaps, axis=0)
else:
pointings_radec = NP.hstack((NP.asarray(lst-pointing_init[0]).reshape(-1,1), pointing_init[1]+NP.zeros(n_snaps).reshape(-1,1)))
pointings_hadec = NP.hstack(((lst-pointings_radec[:,0]).reshape(-1,1), pointings_radec[:,1].reshape(-1,1)))
pointings_altaz = GEOM.hadec2altaz(pointings_hadec, MWA_latitude, units='degrees')
pointings_dircos = GEOM.altaz2dircos(pointings_altaz, units='degrees')
delay_matrix = DLY.delay_envelope(intrfrmtr.baseline, pointings_dircos, units='mks')
pbeams = []
m2s = []
for i in xrange(n_snaps):
havect = lst[i] - ravect
altaz = GEOM.hadec2altaz(NP.hstack((havect.reshape(-1,1),decvect.reshape(-1,1))), MWA_latitude, units='degrees')
# m1, m2, d12 = GEOM.spherematch(pointings[i,0], pointings[i,1], ravect, decvect, 90.0, maxmatches=0)
roi_altaz = NP.asarray(NP.where(altaz[:,0] >= 0.0)).ravel()
pb = PB.primary_beam_generator(altaz[roi_altaz,:], freq, telescope='mwa', skyunits='altaz', freq_scale='Hz', phase_center=pointings_altaz[i,:])
pbeams += [pb]
m2s += [roi_altaz]
## Plotting animation
