def test_slalib(self, mjd, config):
from pyslalib import slalib
ra = numpy.zeros(len(mjd), 'float')
dec = numpy.zeros(len(mjd), 'float')
for i in range(len(mjd)):
# Calculate sun's (topocentric) position.
#ra_RAD, dec_RAD, diam = slalib.sla_rdplan(mjd[i], 0,
# config['longitude']*_deg2rad, config['latitude']*_deg2rad)
# Sun's (geocentric?) position.
bary_vel, bary_pos, helio_vel, helio_pos = slalib.sla_evp(
mjd, 2000)
sun_pos = -1 * (bary_pos)
ra_RAD, dec_RAD = slalib.sla_dcc2s(sun_pos)
ra[i] = ra_RAD * _rad2deg
dec[i] = dec_RAD * _rad2deg
print "Sun: Test_slalib results"
print " ... ra(slalib)"
print ra
print " ... ra(self)"
print self.ra
print self.ra.min(), self.ra.max()
print " ... dec(slalib)"
print dec
print " ... dec(self)"
print self.dec
def helio_geo_correction(ra, dec, mjd, st):
"""Motion of earth's center in heliocentric frame"""
# line-of-sight unit vector to astronomical object
k_los = sla_dcs2c(ra.radian, dec.radian)
# Velocity and position of earth in barycentric and heliocentric frames
# Units are AU and AU/s
vel_bary, pos_bary, vel_hel, pos_hel = sla_evp(mjd, 2000.0)
# Radial velocity correction (km/s) due to helio-geocentric transformation
# Positive when earth is moving away from object
return u.AU.to(u.km, -np.dot(vel_hel, k_los))
def compute_lsrk(self):
""" Computes the LSR in km/s
uses the MJD, RA and DEC of observation to compute
along with the telescope location. Requires pyslalib
"""
ra = Angle(self.header[b'src_raj'], unit='hourangle')
dec = Angle(self.header[b'src_dej'], unit='degree')
mjdd = self.header[b'tstart']
rarad = ra.to('radian').value
dcrad = dec.to('radian').value
last = self.compute_lst()
tellat = np.deg2rad(self.coords[0])
tellong = np.deg2rad(self.coords[1])
# convert star position to vector
starvect = s.sla_dcs2c(rarad, dcrad)
# velocity component in ra,dec due to Earth rotation
Rgeo = s.sla_rverot(tellat, rarad, dcrad, last)
# get Barycentric and heliocentric velocity and position of the Earth.
evp = s.sla_evp(mjdd, 2000.0)
dvb = evp[0] # barycentric velocity vector, in AU/sec
dpb = evp[1] # barycentric position vector, in AU
dvh = evp[2] # heliocentric velocity vector, in AU/sec
dph = evp[3] # heliocentric position vector, in AU
# dot product of vector to object and heliocentric velocity
# convert AU/sec to km/sec
vcorhelio = -s.sla_dvdv(starvect, dvh) * 149.597870e6
vcorbary = -s.sla_dvdv(starvect, dvb) * 149.597870e6
# rvlsrd is velocity component in ra,dec direction due to the Sun's
# motion with respect to the "dynamical" local standard of rest
rvlsrd = s.sla_rvlsrd(rarad, dcrad)
# rvlsrk is velocity component in ra,dec direction due to i
# the Sun's motion w.r.t the "kinematic" local standard of rest
rvlsrk = s.sla_rvlsrk(rarad, dcrad)
# rvgalc is velocity component in ra,dec direction due to
#the rotation of the Galaxy.
rvgalc = s.sla_rvgalc(rarad, dcrad)
totalhelio = Rgeo + vcorhelio
totalbary = Rgeo + vcorbary
totallsrk = totalhelio + rvlsrk
totalgal = totalbary + rvlsrd + rvgalc
return totallsrk
def rvel(self, mjdd, radeg, decdeg):
global tellat, tellong, telelev
last = self.hlst(mjdd) # apparent LST in radians
# convert ra,dec to radians
rarad = radeg * math.pi / 180.0
dcrad = decdeg * math.pi / 180.0
# convert star position to vector
starvect = s.sla_dcs2c(rarad, dcrad)
# velocity component in ra,dec due to Earth rotation
Rgeo = s.sla_rverot(tellat, rarad, dcrad, last)
# get Barycentric and heliocentric velocity and position of the Earth.
evp = s.sla_evp(mjdd, 2000.0)
dvb = evp[0] # barycentric velocity vector, in AU/sec
dpb = evp[1] # barycentric position vector, in AU
dvh = evp[2] # heliocentric velocity vector, in AU/sec
dph = evp[3] # heliocentric position vector, in AU
# dot product of vector to object and heliocentric velocity
# convert AU/sec to km/sec
vcorhelio = -s.sla_dvdv(starvect, dvh) * 149.597870e6
vcorbary = -s.sla_dvdv(starvect, dvb) * 149.597870e6
# rvlsrd is velocity component in ra,dec direction due to the Sun's motion with
# respect to the "dynamical" local standard of rest
rvlsrd = s.sla_rvlsrd(rarad, dcrad)
# rvlsrk is velocity component in ra,dec direction due to the Sun's motion with
# respect to the "kinematic" local standard of rest
rvlsrk = s.sla_rvlsrk(rarad, dcrad)
# rvgalc is velocity component in ra,dec direction due to the rotation of the Galaxy.
rvgalc = s.sla_rvgalc(rarad, dcrad)
totalhelio = Rgeo + vcorhelio
totalbary = Rgeo + vcorbary
totallsrk = totalhelio + rvlsrk
totalgal = totalbary + rvlsrd + rvgalc
# ('UTHr', 'LST', 'Geo', 'Helio', 'Total Helio', 'LSRK', 'Galacto')
#(hour,last*12.0/math.pi,Rgeo,vcorb,totalhelio,totallsrk,totalgal)
# resulting velocities in km/sec
return ((mjdd, last * 12.0 / math.pi, Rgeo, totalhelio, totalbary,
totallsrk, totalgal))
def rvcorr(hdr):
"""Calculate helio- and geo-centric corrections to radial velocities
The result should be subtracted from the observed (topocentric)
velocities in order to give velocities in the heliocentric frame.
"""
# The following page was very helpful in pointing to the relevant
# SLALIB routines and how to use them
# http://star-www.rl.ac.uk/docs/sun67.htx/node230.html
# Object coordinates
ra = coord.RA(hdr["RA"], U.hour)
dec = coord.Dec(hdr["DEC"], U.degree)
# Modified Julian Date
jdate = float(hdr["MJD"])
# Sidereal time
st = coord.Angle((hdr["ST"]), U.hour)
# line-of-sight unit vector to astronomical object
k_los = sla_dcs2c(ra.radians, dec.radians)
# Velocity and position of earth in barycentric and heliocentric frames
# Units are AU and AU/s
vel_bary, pos_bary, vel_hel, pos_hel = sla_evp(jdate, 2000.0)
# Radial velocity correction (km/s) due to helio-geocentric transformation
# Positive when earth is moving away from object
vcorr_hel = U.AU.to(U.km, -np.dot(vel_hel, k_los))
# Long/lat/altitude of observatory (radians, radians, meters)
obs_id, obs_name, obs_long, obs_lat, obs_height = sla_obs(0, "KECK1")
# Radial velocity correction (km/s) due to geo-topocentric transformation
# Positive when observatory is moving away from object
vcorr_geo = sla_rverot(obs_lat, ra.radians, dec.radians, st.radians)
return vcorr_hel + vcorr_geo
def test_slalib(self, mjd, config):
from pyslalib import slalib
ra = numpy.zeros(len(mjd), 'float')
dec = numpy.zeros(len(mjd), 'float')
for i in range(len(mjd)):
# Calculate sun's (topocentric) position.
#ra_RAD, dec_RAD, diam = slalib.sla_rdplan(mjd[i], 0,
# config['longitude']*_deg2rad, config['latitude']*_deg2rad)
# Sun's (geocentric?) position.
bary_vel, bary_pos, helio_vel, helio_pos = slalib.sla_evp(mjd, 2000)
sun_pos = -1 * (bary_pos)
ra_RAD, dec_RAD = slalib.sla_dcc2s(sun_pos)
ra[i] = ra_RAD * _rad2deg
dec[i] = dec_RAD * _rad2deg
print "Sun: Test_slalib results"
print " ... ra(slalib)"
print ra
print " ... ra(self)"
print self.ra
print self.ra.min(), self.ra.max()
print " ... dec(slalib)"
print dec
print " ... dec(self)"
print self.dec
