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near_field can now be specified as the cat_type in the phasing method…
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…. This will first apply sidereal far-field phasing, then apply near-field corrections.
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@baron-de-montblanc
baron-de-montblanc committed Jan 7, 2025
1 parent 42adbe7 commit ba8783f
Showing 1 changed file with 43 additions and 72 deletions.
115 changes: 43 additions & 72 deletions src/pyuvdata/uvdata/uvdata.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4354,6 +4354,24 @@ def _apply_w_proj(self, *, new_w_vals, old_w_vals, select_mask=None):
(-1j * 2 * np.pi) * delta_w_lambda[:, :, None]
)

def unproject_near_field(self, flipconj=False):
"""
Undo near-field phasing.

TODO: How to implement this/Is it needed?

Parameters
----------
flipconj : bool
Is the conjugation scheme "flipped" compared to
what pyuvdata expects? (Default False)

Returns
-------
None (performs operations inplace)
"""
pass

def unproject_phase(
self, *, use_ant_pos=True, select_mask=None, cat_name="unprojected"
):
Expand All @@ -4379,7 +4397,7 @@ def unproject_phase(
If the object is alread unprojected.
"""
# Start by undoing the near-field phasing
self.unproject_near_field()
# self.unproject_near_field()

# select_mask_use is length Nblts, True means should be unprojected
# only select blts that are actually phased.
Expand Down Expand Up @@ -4451,8 +4469,6 @@ def _phase_dict_helper(
cat_name,
lookup_name,
time_array,
dist_units="pc",
near_field=False,
):
"""
Supplies a dictionary with parameters for the phase method to use.
Expand Down Expand Up @@ -4539,8 +4555,6 @@ def _phase_dict_helper(
cat_pm_dec = pm_dec
cat_dist = dist
cat_vrad = vrad
cat_dist_units = dist_units
cat_near_field = near_field
else:
temp_dict = self.phase_center_catalog[cat_id]
cat_type = temp_dict["cat_type"]
Expand All @@ -4555,8 +4569,6 @@ def _phase_dict_helper(
cat_pm_dec = temp_dict.get("cat_pm_dec")
cat_dist = temp_dict.get("cat_dist")
cat_vrad = temp_dict.get("cat_vrad")
cat_dist_units = temp_dict.get("cat_dist_units")
cat_near_field = temp_dict.get("cat_near_field")
else:
# The name of the source is unique!
cat_type = "sidereal" if cat_type is None else cat_type
Expand All @@ -4569,8 +4581,6 @@ def _phase_dict_helper(
cat_pm_dec = pm_dec
cat_dist = dist
cat_vrad = vrad
cat_dist_units = dist_units
cat_near_field = near_field

if (cat_epoch is None) and (cat_type != "unprojected"):
cat_epoch = 1950.0 if (cat_frame in ["fk4", "fk4noeterms"]) else 2000.0
Expand Down Expand Up @@ -4628,8 +4638,6 @@ def _phase_dict_helper(
"cat_vrad": cat_vrad,
"info_source": info_source,
"cat_id": cat_id,
"cat_dist_units": cat_dist_units,
"cat_near_field": cat_near_field,
}

# Finally, make sure everything is a float or an ndarray of floats
Expand All @@ -4639,11 +4647,6 @@ def _phase_dict_helper(
elif (key == "cat_id") and (phase_dict[key] is not None):
# If this is the cat_id, make it an int
phase_dict[key] = int(phase_dict[key])
elif not ((phase_dict[key] is None) or isinstance(phase_dict[key], str)):
# cat_dist_units should be str and cat_near_field should be bool
if (key != "cat_dist_units") and (key != "cat_near_field"):
phase_dict[key] = float(phase_dict[key])

return phase_dict

def _apply_near_field_corrections(self, focus, ra, dec, flipconj=False):
Expand Down Expand Up @@ -4701,41 +4704,11 @@ def _apply_near_field_corrections(self, focus, ra, dec, flipconj=False):

# Set data at each polarization (Npols = 4 usually)
for pol in self.polarization_array:

# For some reason the data need an extra axis?
prev = np.reshape(self.get_data(pol), (self.Nblts, self.Nfreqs, 1))
corr = np.reshape(phase_corrections, (self.Nblts, self.Nfreqs, 1))

self.set_data(corr * prev, pol)

def unproject_near_field(self, flipconj=False):
"""
Undo near-field phasing.

Works by near-field projecting to a distance of infinity.

Parameters
----------
flipconj : bool
Is the conjugation scheme "flipped" compared to
what pyuvdata expects? (Default False)

Returns
-------
None (performs operations inplace)
"""
# Keep the far-field Ra and Dec
key = list(self.phase_center_catalog.keys())[-1]
ra = self.phase_center_catalog[key]["cat_lon"]
dec = self.phase_center_catalog[key]["cat_lat"]

self._apply_near_field_corrections(
focus=1e19 * units.km, # TODO: Is there a better way to do this?
ra=ra,
dec=dec,
flipconj=flipconj,
)

def phase(
self,
*,
Expand All @@ -4756,7 +4729,6 @@ def phase(
use_ant_pos=True,
select_mask=None,
cleanup_old_sources=True,
near_field=False,
):
"""
Phase data to a new direction, supports sidereal, ephemeris and driftscan types.
Expand Down Expand Up @@ -4797,7 +4769,9 @@ def phase(
cat_type : str
Type of phase center to be added. Must be one of:
"sidereal" (fixed RA/Dec), "ephem" (RA/Dec that moves with time),
"driftscan" (fixed az/el position). Default is "sidereal".
"driftscan" (fixed az/el position), "near_field" (applies near-field
corrections to the specified dist, assuming sidereal phase center).
Default is "sidereal".
ephem_times : ndarray of float
Only used when `cat_type="ephem"`. Describes the time for which the values
of `cat_lon` and `cat_lat` are caclulated, in units of JD. Shape is (Npts,).
Expand All @@ -4807,13 +4781,14 @@ def phase(
pm_dec : float
Proper motion in Dec, in units of mas/year. Only used for sidereal phase
centers.
dist : float or ndarray of float or astropy.units.Quantity object
dist : float or ndarray of float or astropy.units.Quantity object.
Distance to the source. Used for sidereal and ephem phase centers,
and for applying near-field corrections. If passed either as a float
(for sidereal phase centers) or as an ndarray of floats of shape (Npts,)
(for ephem phase centers), will be interpreted in units of parsec.
Alternatively, an astropy.units.Quantity object may be passed instead,
in which case the units will be infered automatically.
(for ephem phase centers), will be interpreted in units of parsec for all
cat_types except near_field; in the latter case it will be interpreted
in meters. Alternatively, an astropy.units.Quantity object may be passed
instead, in which case the units will be infered automatically.
vrad : float or ndarray of float
Radial velocity of the source, in units of km/s. Only used for sidereal and
ephem phase centers. Expected to be a float for sidereal phase
Expand All @@ -4831,20 +4806,16 @@ def phase(
select_mask : ndarray of bool
Optional mask for selecting which data to operate on along the blt-axis.
Shape is (Nblts,). Ignored if `use_old_proj` is True.
near_field : bool
Option to apply near-field corrections to the provided
ra, dec, and distance. Defaults to False
(apply far-field corrections only).

Raises
------
ValueError
If the `cat_name` is None.

"""
key = list(self.phase_center_catalog.keys())[-1]
if self.phase_center_catalog[key]["cat_name"] != "":
self.unproject_near_field()
# key = list(self.phase_center_catalog.keys())[-1]
# if self.phase_center_catalog[key]["cat_name"] != "":
# self.unproject_near_field()

if cat_type != "unprojected":
if lon is None:
Expand All @@ -4865,22 +4836,24 @@ def phase(
# Before moving forward with the heavy calculations, we need to do some
# basic housekeeping to make sure that we've got the coordinate data that
# we need in order to proceed.
dist_units = "pc"
if dist is not None:
if isinstance(dist, units.Quantity):
dist_units = dist.unit
dist_qt = copy.deepcopy(dist)
dist = dist.value
else:
dist_qt = dist * units.parsec
if cat_type == "near_field":
dist_qt = dist * units.meters
else:
dist_qt = dist * units.parsec

if near_field:
warnings.warn(
"near_field is set to True, but dist is not an "
"astropy.units.Quantity object. "
"Distance will be interpreted in units of parsec.",
UserWarning,
)
dist = dist_qt.to(
units.parsec
).value # phase_dict internally stores in parsecs

if cat_type == "near_field":
near_field = True
cat_type = "sidereal" # apply far-field phasing BEFORE near-field
else:
near_field = False

phase_dict = self._phase_dict_helper(
lon=lon,
Expand All @@ -4896,8 +4869,6 @@ def phase(
cat_name=cat_name,
lookup_name=lookup_name,
time_array=self.time_array,
dist_units=dist_units,
near_field=near_field,
)

if phase_dict["cat_type"] not in ["ephem", "unprojected"]:
Expand Down

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