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Dcp uvfits rdate fix #1436

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Dcp uvfits rdate fix #1436

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a85d447
Issue #1433: RDATE and DATE-OBS in UVFITS writer
May 3, 2024
316a5cf
Adding EarthLocation to obs_date0 Time
May 3, 2024
1f80f9c
Appeasing linter gods
May 3, 2024
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40 changes: 24 additions & 16 deletions pyuvdata/uvdata/uvfits.py
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
from astropy import constants as const
from astropy.io import fits
from astropy.time import Time
from astropy.coordinates import EarthLocation
from docstring_parser import DocstringStyle

from .. import utils as uvutils
Expand Down Expand Up @@ -59,9 +60,11 @@ def _get_parameter_data(
# angles in uvfits files are stored in degrees, so convert to radians
self.lst_array = np.deg2rad(vis_hdu.data.par("lst"))
if run_check_acceptability:
(latitude, longitude, altitude) = (
self.telescope_location_lat_lon_alt_degrees
)
(
latitude,
longitude,
altitude,
) = self.telescope_location_lat_lon_alt_degrees
uvutils.check_lsts_against_times(
jd_array=self.time_array,
lst_array=self.lst_array,
Expand Down Expand Up @@ -1158,8 +1161,18 @@ def write_uvfits(
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
# Create an astropy.time.Time object from first timestamp.
# This is used to generate DATE-OBS and RDATE keywords
eloc = EarthLocation(
self.telescope_location[0],
self.telescope_location[1],
self.telescope_location[2],
unit="m",
)
obs_date0 = Time(self.time_array[0], format="jd", scale="utc", location=eloc)

# Per AIPS memo 117, DATE-OBS is the YYYY-MM-DD string
hdu.header["DATE-OBS"] = obs_date0.strftime("%Y-%m-%d")

hdu.header["CTYPE2 "] = "COMPLEX "
hdu.header["CRVAL2 "] = 1.0
Expand Down Expand Up @@ -1338,26 +1351,21 @@ def write_uvfits(
else:
ant_hdu.header["FREQ"] = self.freq_array[0, 0]

# RDATE: Reference date when obs started, YYYY-MM-DD
if (self.rdate is None) or (self.rdate == ""):
rdate_obj = Time(np.floor(self.time_array[0]), format="jd", scale="utc")
else:
try:
rdate_obj = Time(self.rdate, scale="utc")
except ValueError:
rdate_obj = Time(np.floor(self.time_array[0]), format="jd", scale="utc")

if self.rdate is None:
ant_hdu.header["RDATE"] = rdate_obj.strftime("%Y-%m-%d")
ant_hdu.header["RDATE"] = obs_date0.strftime("%Y-%m-%d")
else:
ant_hdu.header["RDATE"] = self.rdate

# GSTIA0: Greenwich sidereal time in degrees at zero hours on RDATE
if self.gst0 is None:
ant_hdu.header["GSTIA0"] = rdate_obj.sidereal_time("apparent", "tio").deg
ant_hdu.header["GSTIA0"] = obs_date0.sidereal_time("apparent", "tio").deg
else:
ant_hdu.header["GSTIA0"] = self.gst0

# UT1UTC: the difference between UT1 and UTC in seconds on RDATE
if self.dut1 is None:
ant_hdu.header["UT1UTC"] = float(rdate_obj.delta_ut1_utc)
ant_hdu.header["UT1UTC"] = float(obs_date0.delta_ut1_utc)
else:
ant_hdu.header["UT1UTC"] = self.dut1

Expand Down