def iod_obs_tod(location: EarthLocation, epoch: Time):
"""
Get the true of date (tod) position-velocity vector of the observatory
Parameters
----------
location: `~astropy.coordinates.EarthLocation`
Position vector in body fixed reference frame.
epoch: `~astropy.time.Time`
Returns
-------
pos, vel: ~astropy.units.Quantity
Position and velocity vector of the observation, in tod frame
"""
from astropy.coordinates.earth import OMEGA_EARTH
from astropy import _erfa as erfa
assert isinstance(location, EarthLocation)
assert isinstance(epoch, Time)
dut = epoch.get_delta_ut1_utc(iers_table=iers_table)
ut1 = Time(epoch.mjd + dut.to_value('day'), format='mjd', scale='ut1')
earth_rotation_angle = erfa.era00(ut1.jd1, ut1.jd2) * u.rad
loc = location.get_itrs()
unit = loc.x.unit
loc = np.array([loc.x.value, loc.y.value, loc.z.value])
pos = np.matmul(rotation_matrix(-earth_rotation_angle, 'z'), loc)
vel = [-OMEGA_EARTH.value * pos[1], OMEGA_EARTH.value * pos[0], 0.0]
acc = [-OMEGA_EARTH.value**2 * pos[0], -OMEGA_EARTH.value**2 * pos[1], 0.0]
return pos * unit, \
vel * unit * OMEGA_EARTH.unit, \
acc * unit * OMEGA_EARTH.unit * OMEGA_EARTH.unit
def delta_obs_ra_to_cirs_ra(mjd, longitude, latitude):
"""
difference between radio astronomers observed coords and CIRS coords
Args
====
mjd: (float) modified Julian date
longitude: (float) in degrees or as astropy Angle
latitude: (float) in degrees or as astropy Angle
Return
======
hour angle as astropy.coordinates.Angle
"""
from astropy import _erfa as erfa
from astropy.coordinates.builtin_frames.utils import get_jd12
# get the Earth Rotation Angle
era = erfa.era00(*get_jd12(APt.Time(mjd, format='mjd'), 'ut1'))
logger.debug("delta_obs_ra_to_cirs_ra: ERA = %f rad", era)
logger.debug("delta_obs_ra_to_cirs_ra: ERA = %s",
format_angles(era * 12 / pi))
theta_earth = APc.Angle(era, unit='rad')
# get the time of observation
obs_time = APt.Time(mjd,
format='mjd',
location=(APc.Angle(longitude, unit="deg"),
APc.Angle(latitude, unit="deg")))
# Greenwich apparent sidereal time of observation
gast = obs_time.sidereal_time('apparent', longitude=0) # Greenwich ST
logger.debug("delta_obs_ra_to_cirs_ra: GAST = %s", gast)
logger.debug("delta_obs_ra_to_cirs_ra: delta = %s", gast - theta_earth)
return (gast - theta_earth)
def cirs_to_tee_ra(cirs_ra, time):
from astropy import _erfa as erfa
from astropy.coordinates.builtin_frames.utils import get_jd12
era = erfa.era00(*get_jd12(time, 'ut1'))
theta_earth = Angle(era, unit='rad')
assert (isinstance(time, Time))
assert (isinstance(cirs_ra, Angle))
gast = time.sidereal_time('apparent', longitude=0)
tee_ra = cirs_ra + (gast - theta_earth)
return tee_ra
def cirs_to_itrs_mat(time):
# compute the polar motion p-matrix
xp, yp = get_polar_motion(time)
sp = erfa.sp00(*get_jd12(time, 'tt'))
pmmat = erfa.pom00(xp, yp, sp)
# now determine the Earth Rotation Angle for the input obstime
# era00 accepts UT1, so we convert if need be
era = erfa.era00(*get_jd12(time, 'ut1'))
# c2tcio expects a GCRS->CIRS matrix, but we just set that to an I-matrix
# because we're already in CIRS
return erfa.c2tcio(np.eye(3), era, pmmat)
def cirs_to_itrs_mat(time):
# compute the polar motion p-matrix
xp, yp = get_polar_motion(time)
sp = erfa.sp00(*get_jd12(time, 'tt'))
pmmat = erfa.pom00(xp, yp, sp)
# now determine the Earth Rotation Angle for the input obstime
# era00 accepts UT1, so we convert if need be
era = erfa.era00(*get_jd12(time, 'ut1'))
# c2tcio expects a GCRS->CIRS matrix, but we just set that to an I-matrix
# because we're already in CIRS
return erfa.c2tcio(np.eye(3), era, pmmat)
def _pvobs(self):
'''calculates position and velocity of the observatory
returns position/velocity in AU and AU/d in GCRS reference frame
'''
# convert obs position from WGS84 (lat long) to ITRF geocentric coords in AU
xyz = self.location.to(u.AU).value
# now we need to convert this position to Celestial Coords
# specifically, the GCRS coords.
# conversion from celestial to terrestrial coords given by
# [TRS] = RPOM * R_3(ERA) * RC2I * [CRS]
# where:
# [CRS] is vector in GCRS (geocentric celestial system)
# [TRS] is vector in ITRS (International Terrestrial Ref System)
# ERA is earth rotation angle
# RPOM = polar motion matrix
tt = self.tt
mjd = self.utc.mjd
# we need the IERS values to correct for the precession/nutation of the Earth
iers_tab = IERS.open()
# Find UT1, which is needed to calculate ERA
# uses IERS_B by default , for more recent times use IERS_A download
try:
ut1 = self.ut1
except:
try:
iers_a_file = download_file(IERS_A_URL, cache=True)
iers_a = IERS_A.open(iers_a_file)
print "Trying to download...", iers_a_file
self.delta_ut1_utc = self.get_delta_ut1_utc(iers_a)
ut1 = self.ut1
except:
# fall back to UTC with degraded accuracy
warnings.warn('Cannot calculate UT1: using UTC with degraded accuracy')
ut1 = self.utc
# Gets x,y coords of Celestial Intermediate Pole (CIP) and CIO locator s
# CIO = Celestial Intermediate Origin
# Both in GCRS
X,Y,S = erfa.xys00a(tt.jd1,tt.jd2)
# Get dX and dY from IERS B
dX = np.interp(mjd, iers_tab['MJD'], iers_tab['dX_2000A']) * u.arcsec
dY = np.interp(mjd, iers_tab['MJD'], iers_tab['dY_2000A']) * u.arcsec
# Get GCRS to CIRS matrix
# can be used to convert to Celestial Intermediate Ref Sys
# from GCRS.
rc2i = erfa.c2ixys(X+dX.to(u.rad).value, Y+dY.to(u.rad).value, S)
# Gets the Terrestrial Intermediate Origin (TIO) locator s'
# Terrestrial Intermediate Ref Sys (TIRS) defined by TIO and CIP.
# TIRS related to to CIRS by Earth Rotation Angle
sp = erfa.sp00(tt.jd1,tt.jd2)
# Get X and Y from IERS B
# X and Y are
xp = np.interp(mjd, iers_tab['MJD'], iers_tab['PM_x']) * u.arcsec
yp = np.interp(mjd, iers_tab['MJD'], iers_tab['PM_y']) * u.arcsec
# Get the polar motion matrix. Relates ITRF to TIRS.
rpm = erfa.pom00(xp.to(u.rad).value, yp.to(u.rad).value, sp)
# multiply ITRF position of obs by transpose of polar motion matrix
# Gives Intermediate Ref Frame position of obs
x,y,z = np.array([rpmMat.T.dot(xyz) for rpmMat in rpm]).T
# Functions of Earth Rotation Angle, theta
# Theta is angle bewtween TIO and CIO (along CIP)
# USE UT1 here.
theta = erfa.era00(ut1.jd1,ut1.jd2)
S,C = np.sin(theta),np.cos(theta)
# Position #GOT HERE
pos = np.asarray([C*x - S*y, S*x + C*y, z]).T
# multiply by inverse of GCRS to CIRS matrix
# different methods for scalar times vs arrays
if pos.ndim > 1:
pos = np.array([np.dot(rc2i[j].T,pos[j]) for j in range(len(pos))])
else:
pos = np.dot(rc2i.T,pos)
# Velocity
vel = np.asarray([SR*(-S*x - C*y), SR*(C*x-S*y), np.zeros_like(x)]).T
# multiply by inverse of GCRS to CIRS matrix
if vel.ndim > 1:
vel = np.array([np.dot(rc2i[j].T,vel[j]) for j in range(len(pos))])
else:
vel = np.dot(rc2i.T,vel)
#return position and velocity
return pos,vel
def _pvobs(self):
'''calculates position and velocity of the observatory
returns position/velocity in AU and AU/d in GCRS reference frame
'''
# convert obs position from WGS84 (lat long) to ITRF geocentric coords in AU
xyz = self.location.to(u.AU).value
# now we need to convert this position to Celestial Coords
# specifically, the GCRS coords.
# conversion from celestial to terrestrial coords given by
# [TRS] = RPOM * R_3(ERA) * RC2I * [CRS]
# where:
# [CRS] is vector in GCRS (geocentric celestial system)
# [TRS] is vector in ITRS (International Terrestrial Ref System)
# ERA is earth rotation angle
# RPOM = polar motion matrix
tt = self.tt
mjd = self.utc.mjd
# we need the IERS values to correct for the precession/nutation of the Earth
iers_tab = IERS.open()
# Find UT1, which is needed to calculate ERA
# uses IERS_B by default , for more recent times use IERS_A download
try:
ut1 = self.ut1
except:
try:
iers_a_file = download_file(IERS_A_URL, cache=True)
iers_a = IERS_A.open(iers_a_file)
self.delta_ut1_utc = self.get_delta_ut1_utc(iers_a)
ut1 = self.ut1
except:
# fall back to UTC with degraded accuracy
warnings.warn(
'Cannot calculate UT1: using UTC with degraded accuracy')
ut1 = self.utc
# Gets x,y coords of Celestial Intermediate Pole (CIP) and CIO locator s
# CIO = Celestial Intermediate Origin
# Both in GCRS
X, Y, S = erfa.xys00a(tt.jd1, tt.jd2)
# Get dX and dY from IERS B
dX = np.interp(mjd, iers_tab['MJD'], iers_tab['dX_2000A']) * u.arcsec
dY = np.interp(mjd, iers_tab['MJD'], iers_tab['dY_2000A']) * u.arcsec
# Get GCRS to CIRS matrix
# can be used to convert to Celestial Intermediate Ref Sys
# from GCRS.
rc2i = erfa.c2ixys(X + dX.to(u.rad).value, Y + dY.to(u.rad).value, S)
# Gets the Terrestrial Intermediate Origin (TIO) locator s'
# Terrestrial Intermediate Ref Sys (TIRS) defined by TIO and CIP.
# TIRS related to to CIRS by Earth Rotation Angle
sp = erfa.sp00(tt.jd1, tt.jd2)
# Get X and Y from IERS B
# X and Y are
xp = np.interp(mjd, iers_tab['MJD'], iers_tab['PM_x']) * u.arcsec
yp = np.interp(mjd, iers_tab['MJD'], iers_tab['PM_y']) * u.arcsec
# Get the polar motion matrix. Relates ITRF to TIRS.
rpm = erfa.pom00(xp.to(u.rad).value, yp.to(u.rad).value, sp)
# multiply ITRF position of obs by transpose of polar motion matrix
# Gives Intermediate Ref Frame position of obs
x, y, z = np.array([rpmMat.T.dot(xyz) for rpmMat in rpm]).T
# Functions of Earth Rotation Angle, theta
# Theta is angle bewtween TIO and CIO (along CIP)
# USE UT1 here.
theta = erfa.era00(ut1.jd1, ut1.jd2)
S, C = np.sin(theta), np.cos(theta)
# Position #GOT HERE
pos = np.asarray([C * x - S * y, S * x + C * y, z]).T
# multiply by inverse of GCRS to CIRS matrix
# different methods for scalar times vs arrays
if pos.ndim > 1:
pos = np.array(
[np.dot(rc2i[j].T, pos[j]) for j in range(len(pos))])
else:
pos = np.dot(rc2i.T, pos)
# Velocity
vel = np.asarray(
[SR * (-S * x - C * y), SR * (C * x - S * y),
np.zeros_like(x)]).T
# multiply by inverse of GCRS to CIRS matrix
if vel.ndim > 1:
vel = np.array(
[np.dot(rc2i[j].T, vel[j]) for j in range(len(pos))])
else:
vel = np.dot(rc2i.T, vel)
#return position and velocity
return pos, vel
def gcrs2irts_matrix_b(t, eop):
"""
Ref: http://www.iausofa.org/sofa_pn_c.pdf
Purpose:
This function calculates the cartesian transformation matrix for transforming GCRS to ITRS or vice versa
:param eop:
eop is a dataframe containing the Earth Orientation Parameters as per IAU definitions
:param t:
t is a datetime object or a list of datetime objects with the UTC times for the transformation matrix to be
calculated for
:return:
matrix is a [3,3] numpy array or list of arrays used for transforming GCRS to ITRS or vice versa at the
specified times; ITRS = matrix @ GCRS
"""
if not (isinstance(t, Iterable)):
t = [t]
matrix = []
for ti in t:
year = ti.year
month = ti.month
day = ti.day
hour = ti.hour
minute = ti.minute
second = ti.second
# TT (MJD). */
djmjd0, date = erfa.cal2jd(iy=year, im=month, id=day)
# jd = djmjd0 + date
day_frac = (60.0 * (60.0 * hour + minute) + second) / DAYSEC
utc = date + day_frac
Dat = erfa.dat(year, month, day, day_frac)
tai = utc + Dat / DAYSEC
tt = tai + 32.184 / DAYSEC
# UT1. */
dut1 = eop["UT1-UTC"][date] * (
1 - day_frac) + eop["UT1-UTC"][date + 1] * day_frac
tut = day_frac + dut1 / DAYSEC
# ut1 = date + tut
# CIP and CIO, IAU 2006/2000A. */
x, y, s = erfa.xys06a(djmjd0, tt)
# X, Y offsets
dx06 = (eop["dX"][date] *
(1 - day_frac) + eop["dX"][date + 1] * day_frac) * DAS2R
dy06 = (eop["dY"][date] *
(1 - day_frac) + eop["dY"][date + 1] * day_frac) * DAS2R
# Add CIP corrections. */
x = x + dx06
y = y + dy06
# GCRS to CIRS matrix. */
rc2i = erfa.c2ixys(x, y, s)
# Earth rotation angle. */
era = erfa.era00(djmjd0 + date, tut)
# Form celestial-terrestrial matrix (no polar motion yet). */
rc2ti = erfa.cr(rc2i)
rc2ti = eraRZ(era, rc2ti)
#rc2ti = erfa.rz(era, rc2ti)
# Polar motion matrix (TIRS->ITRS, IERS 2003). */
xp = (eop["x"][date] *
(1 - day_frac) + eop["x"][date + 1] * day_frac) * DAS2R
yp = (eop["y"][date] *
(1 - day_frac) + eop["y"][date + 1] * day_frac) * DAS2R
rpom = erfa.pom00(xp, yp, erfa.sp00(djmjd0, tt))
# Form celestial-terrestrial matrix (including polar motion). */
rc2it = erfa.rxr(rpom, rc2ti)
matrix.append(rc2it)
if len(matrix) == 1:
matrix = matrix[0]
return matrix
def __call__(self, md, exposureId=None):
"""Construct a VisitInfo and strip associated data from the metadata.
Parameters
----------
md : `lsst.daf.base.PropertyList` or `lsst.daf.base.PropertySet`
Metadata to pull from.
Items that are used are stripped from the metadata.
exposureId : `int`, optional
Ignored. Here for compatibility with `MakeRawVisitInfo`.
Returns
-------
visitInfo : `lsst.afw.image.VisitInfo`
`~lsst.afw.image.VisitInfo` derived from the header using
a `~astro_metadata_translator.MetadataTranslator`.
"""
argDict = dict()
obsInfo = ObservationInfo(md, translator_class=self.metadataTranslator)
# Strip all the cards out that were used
for c in obsInfo.cards_used:
del md[c]
# Map the translated information into a form suitable for VisitInfo
if obsInfo.exposure_time is not None:
argDict["exposureTime"] = obsInfo.exposure_time.to_value("s")
if obsInfo.dark_time is not None:
argDict["darkTime"] = obsInfo.dark_time.to_value("s")
argDict["exposureId"] = obsInfo.detector_exposure_id
# VisitInfo uses the middle of the observation for the date
if obsInfo.datetime_begin is not None and obsInfo.datetime_end is not None:
tdelta = obsInfo.datetime_end - obsInfo.datetime_begin
middle = obsInfo.datetime_begin + 0.5 * tdelta
# DateTime uses nanosecond resolution, regardless of the resolution
# of the original date
middle.precision = 9
# isot is ISO8601 format with "T" separating date and time and no
# time zone
argDict["date"] = DateTime(middle.tai.isot, DateTime.TAI)
# Derive earth rotation angle from UT1 (being out by a second is not
# a big deal given the uncertainty over exactly what part of the
# observation we are needing it for).
# ERFA needs a UT1 time split into two floats
# We ignore any problems with DUT1 not being defined for now.
try:
ut1time = middle.ut1
except iers.IERSRangeError:
ut1time = middle
era = erfa.era00(ut1time.jd1, ut1time.jd2)
argDict["era"] = era * radians
else:
argDict["date"] = DateTime()
# Coordinates
if obsInfo.tracking_radec is not None:
icrs = obsInfo.tracking_radec.transform_to("icrs")
argDict["boresightRaDec"] = SpherePoint(icrs.ra.degree,
icrs.dec.degree,
units=degrees)
altaz = obsInfo.altaz_begin
if altaz is not None:
argDict["boresightAzAlt"] = SpherePoint(altaz.az.degree,
altaz.alt.degree,
units=degrees)
argDict["boresightAirmass"] = obsInfo.boresight_airmass
if obsInfo.boresight_rotation_angle is not None:
argDict[
"boresightRotAngle"] = obsInfo.boresight_rotation_angle.degree * degrees
if obsInfo.boresight_rotation_coord is not None:
rotType = RotType.UNKNOWN
if obsInfo.boresight_rotation_coord == "sky":
rotType = RotType.SKY
argDict["rotType"] = rotType
# Weather and Observatory Location
temperature = float("nan")
if obsInfo.temperature is not None:
temperature = obsInfo.temperature.to_value(
"deg_C", astropy.units.temperature())
pressure = float("nan")
if obsInfo.pressure is not None:
pressure = obsInfo.pressure.to_value("Pa")
relative_humidity = float("nan")
if obsInfo.relative_humidity is not None:
relative_humidity = obsInfo.relative_humidity
argDict["weather"] = Weather(temperature, pressure, relative_humidity)
if obsInfo.location is not None:
geolocation = obsInfo.location.to_geodetic()
argDict["observatory"] = Observatory(
geolocation.lon.degree * degrees,
geolocation.lat.degree * degrees,
geolocation.height.to_value("m"))
for key in list(
argDict.keys()): # use a copy because we may delete items
if argDict[key] is None:
self.log.warn("argDict[{}] is None; stripping".format(
key, argDict[key]))
del argDict[key]
return VisitInfo(**argDict)
def gcrs_posvel_from_itrf(loc, toas, obsname="obs"):
"""Return a list of PosVel instances for the observatory at the TOA times.
Observatory location should be given in the loc argument as an astropy
EarthLocation object. This location will be in the ITRF frame (i.e.
co-rotating with the Earth).
The optional obsname argument will be used as label in the returned
PosVel instance.
This routine returns a list of PosVel instances, containing the
positions (m) and velocities (m / s) at the times of the toas and
referenced to the Earth-centered Inertial (ECI, aka GCRS) coordinates.
This routine is basically SOFA's pvtob() [Position and velocity of
a terrestrial observing station] with an extra rotation from c2ixys()
[Form the celestial to intermediate-frame-of-date matrix given the CIP
X,Y and the CIO locator s].
"""
unpack = False
# If the input is a single TOA (i.e. a row from the table),
# then put it into a list
if type(toas) == table.row.Row:
ttoas = Time([toas["mjd"]])
unpack = True
elif type(toas) == table.table.Table:
ttoas = toas["mjd"]
elif isinstance(toas, Time):
if toas.isscalar:
ttoas = Time([toas])
unpack = True
else:
ttoas = toas
else:
if np.isscalar(toas):
ttoas = Time([toas], format="mjd")
unpack = True
else:
ttoas = toas
N = len(ttoas)
if len(ttoas.shape) != 1:
raise ValueError("At most one-dimensional array of times possible, "
"shape was {}".format(ttoas.shape))
# Get various times from the TOAs as arrays
tts = np.asarray([(t.jd1, t.jd2) for t in ttoas.tt]).T
ut1s = np.asarray([(t.jd1, t.jd2) for t in ttoas.ut1]).T
mjds = np.asarray(ttoas.mjd)
iers_b = get_iers_b_up_to_date(mjds.max())
# Get x, y coords of Celestial Intermediate Pole and CIO locator s
X, Y, S = erfa.xys00a(*tts)
# Get dX and dY from IERS A in arcsec and convert to radians
# dX = np.interp(mjds, iers_tab['MJD'], iers_tab['dX_2000A_B']) * asec2rad
# dY = np.interp(mjds, iers_tab['MJD'], iers_tab['dY_2000A_B']) * asec2rad
# Get dX and dY from IERS B in arcsec and convert to radians
dX = np.interp(mjds, iers_b["MJD"].to_value(u.d),
iers_b["dX_2000A"].to_value(u.rad))
dY = np.interp(mjds, iers_b["MJD"].to_value(u.d),
iers_b["dY_2000A"].to_value(u.rad))
# Get GCRS to CIRS matrices
rc2i = erfa.c2ixys(X + dX, Y + dY, S)
# Gets the TIO locator s'
sp = erfa.sp00(*tts)
# Get X and Y from IERS A in arcsec and convert to radians
# xp = np.interp(mjds, iers_tab['MJD'], iers_tab['PM_X_B']) * asec2rad
# yp = np.interp(mjds, iers_tab['MJD'], iers_tab['PM_Y_B']) * asec2rad
# Get X and Y from IERS B in arcsec and convert to radians
xp = np.interp(mjds, iers_b["MJD"].to_value(u.d),
iers_b["PM_x"].to_value(u.rad))
yp = np.interp(mjds, iers_b["MJD"].to_value(u.d),
iers_b["PM_y"].to_value(u.rad))
# Get the polar motion matrices
rpm = erfa.pom00(xp, yp, sp)
# Observatory geocentric coords in m
xyzm = np.array([a.to_value(u.m) for a in loc.geocentric])
x, y, z = np.dot(xyzm, rpm).T
# Functions of Earth Rotation Angle
theta = erfa.era00(*ut1s)
s, c = np.sin(theta), np.cos(theta)
sx, cx = s * x, c * x
sy, cy = s * y, c * y
# Initial positions and velocities
iposs = np.asarray([cx - sy, sx + cy, z]).T
ivels = np.asarray([OM * (-sx - cy), OM * (cx - sy), np.zeros_like(x)]).T
# There is probably a way to do this with np.einsum or something...
# and here it is .
poss = np.empty((N, 3), dtype=np.float64)
vels = np.empty((N, 3), dtype=np.float64)
poss = np.einsum("ij,ijk->ik", iposs, rc2i)
vels = np.einsum("ij,ijk->ik", ivels, rc2i)
r = PosVel(poss.T * u.m, vels.T * u.m / u.s, obj=obsname, origin="earth")
if unpack:
return r[0]
else:
return r
def observationInfo2visitInfo(obsInfo, log=None):
"""Construct a `~lsst.afw.image.VisitInfo` from an
`~astro_metadata_translator.ObservationInfo`
Parameters
----------
obsInfo : `astro_metadata_translator.ObservationInfo`
Information gathered from the observation metadata.
log : `logging.Logger` or `lsst.log.Log`, optional
Logger to use for logging informational messages.
If `None` logging will be disabled.
Returns
-------
visitInfo : `lsst.afw.image.VisitInfo`
`~lsst.afw.image.VisitInfo` derived from the supplied
`~astro_metadata_translator.ObservationInfo`.
"""
argDict = dict()
# Map the translated information into a form suitable for VisitInfo
if obsInfo.exposure_time is not None:
argDict["exposureTime"] = obsInfo.exposure_time.to_value("s")
if obsInfo.dark_time is not None:
argDict["darkTime"] = obsInfo.dark_time.to_value("s")
argDict["exposureId"] = obsInfo.detector_exposure_id
# VisitInfo uses the middle of the observation for the date
if obsInfo.datetime_begin is not None and obsInfo.datetime_end is not None:
tdelta = obsInfo.datetime_end - obsInfo.datetime_begin
middle = obsInfo.datetime_begin + 0.5*tdelta
# DateTime uses nanosecond resolution, regardless of the resolution
# of the original date
middle.precision = 9
# isot is ISO8601 format with "T" separating date and time and no
# time zone
argDict["date"] = DateTime(middle.tai.isot, DateTime.TAI)
# Derive earth rotation angle from UT1 (being out by a second is not
# a big deal given the uncertainty over exactly what part of the
# observation we are needing it for).
# ERFA needs a UT1 time split into two floats
# We ignore any problems with DUT1 not being defined for now.
try:
# Catch any warnings about the time being in the future
# since there is nothing we can do about that for simulated
# data and it tells us nothing for data from the past.
with warnings.catch_warnings():
warnings.simplefilter("ignore", category=astropy.utils.exceptions.AstropyWarning)
ut1time = middle.ut1
except iers.IERSRangeError:
ut1time = middle
era = erfa.era00(ut1time.jd1, ut1time.jd2)
argDict["era"] = era * radians
else:
argDict["date"] = DateTime()
# Coordinates
if obsInfo.tracking_radec is not None:
icrs = obsInfo.tracking_radec.transform_to("icrs")
argDict["boresightRaDec"] = SpherePoint(icrs.ra.degree,
icrs.dec.degree, units=degrees)
altaz = obsInfo.altaz_begin
if altaz is not None:
argDict["boresightAzAlt"] = SpherePoint(altaz.az.degree,
altaz.alt.degree, units=degrees)
argDict["boresightAirmass"] = obsInfo.boresight_airmass
if obsInfo.boresight_rotation_angle is not None:
argDict["boresightRotAngle"] = obsInfo.boresight_rotation_angle.degree*degrees
if obsInfo.boresight_rotation_coord is not None:
rotType = RotType.UNKNOWN
if obsInfo.boresight_rotation_coord == "sky":
rotType = RotType.SKY
argDict["rotType"] = rotType
# Weather and Observatory Location
temperature = float("nan")
if obsInfo.temperature is not None:
temperature = obsInfo.temperature.to_value("deg_C", astropy.units.temperature())
pressure = float("nan")
if obsInfo.pressure is not None:
pressure = obsInfo.pressure.to_value("Pa")
relative_humidity = float("nan")
if obsInfo.relative_humidity is not None:
relative_humidity = obsInfo.relative_humidity
argDict["weather"] = Weather(temperature, pressure, relative_humidity)
if obsInfo.location is not None:
geolocation = obsInfo.location.to_geodetic()
argDict["observatory"] = Observatory(geolocation.lon.degree*degrees,
geolocation.lat.degree*degrees,
geolocation.height.to_value("m"))
for key in list(argDict.keys()): # use a copy because we may delete items
if argDict[key] is None:
if log is not None:
log.warn("argDict[{}] is None; stripping".format(key, argDict[key]))
del argDict[key]
return VisitInfo(**argDict)
def JD2era(JD):
JD_time = Time(JD, format="jd", scale="ut1")
era = _erfa.era00(JD_time.jd1, JD_time.jd2)
return era
