def datetime2mjd_tdb(date, obsvr_long, obsvr_lat, obsvr_hgt, dbg=False):
auinkm = 149597870.691
# Compute MJD_UTC from passed datetime
mjd_utc = datetime2mjd_utc(date)
if mjd_utc == None: return None
# Compute MJD_TT
mjd_tt = mjd_utc2mjd_tt(mjd_utc, dbg)
# Compute TT->TDB
# Convert geodetic position to geocentric distance from spin axis (r) and from
# equatorial plane (z)
(r, z) = S.sla_geoc(obsvr_lat, obsvr_hgt)
ut1 = compute_ut1(mjd_utc, dbg)
if dbg: print "UT1=", ut1
# Compute relativistic clock correction TDB->TT
tdb_tt = S.sla_rcc(mjd_tt, ut1, -obsvr_long, r*auinkm, z*auinkm)
if dbg: print "(TDB-TT)=", tdb_tt
if dbg: print "(CT-UT)=", S.sla_dtt(mjd_utc)+tdb_tt
mjd_tdb = mjd_tt + (tdb_tt/86400.0)
return mjd_tdb
def datetime2mjd_tdb(date, obsvr_long, obsvr_lat, obsvr_hgt, dbg=False):
auinkm = 149597870.691
# Compute MJD_UTC from passed datetime
mjd_utc = datetime2mjd_utc(date)
if mjd_utc is None:
return None
# Compute MJD_TT
mjd_tt = mjd_utc2mjd_tt(mjd_utc, dbg)
# Compute TT->TDB
# Convert geodetic position to geocentric distance from spin axis (r) and from
# equatorial plane (z)
(r, z) = S.sla_geoc(obsvr_lat, obsvr_hgt)
ut1 = compute_ut1(mjd_utc, dbg)
if dbg:
print("UT1=", ut1)
# Compute relativistic clock correction TDB->TT
tdb_tt = S.sla_rcc(mjd_tt, ut1, -obsvr_long, r * auinkm, z * auinkm)
if dbg:
print("(TDB-TT)=", tdb_tt)
if dbg:
print("(CT-UT)=", S.sla_dtt(mjd_utc) + tdb_tt)
mjd_tdb = mjd_tt + (tdb_tt / 86400.0)
return mjd_tdb
def mjd_utc_to_mjd_tt(mjd_utc, dbg=False):
"""Converts a MJD in UTC (MJD_UTC) to a MJD in TT (Terrestial Time) which is
needed for any position/ephemeris-based calculations.UTC
UTC->TT consists of: UTC->TAI = 10s offset + 24 leapseconds (last one 2009 Jan 1.)
TAI->TT = 32.184s fixed offset"""
tt_utc = slalib.sla_dtt(mjd_utc)
if dbg: print 'TT-UTC(s)=', tt_utc
mjd_tt = mjd_utc + (tt_utc/86400.0)
if dbg: print 'MJD(TT) = ', mjd_tt
return mjd_tt
def mjd_utc2mjd_tt(mjd_utc, dbg=False):
'''Converts a MJD in UTC (MJD_UTC) to a MJD in TT (Terrestial Time) which is
needed for any position/ephemeris-based calculations.
UTC->TT consists of: UTC->TAI = 10s offset + 24 leapseconds (last one 2009 Jan 1.)
TAI->TT = 32.184s fixed offset'''
# UTC->TT offset
tt_utc = S.sla_dtt(mjd_utc)
if dbg: print('TT-UTC(s)=', tt_utc)
# Correct MJD to MJD(TT)
mjd_tt = mjd_utc + (tt_utc / 86400.0)
if dbg: print('MJD(TT) = ', mjd_tt)
return mjd_tt
def ut_mjd_to_tdb(ut_mjd):
tdb = ut_mjd + (sla.sla_dtt(ut_mjd) / 86400)
return tdb
def calc_tabular_interval(m, tdb):
'''Find n, the tabular interval (Ast.Alg., p.99).'''
return m + (sla.sla_dtt(tdb) / 86400)
# ra.append(math.degrees(r1))
# dec.append(math.degrees(d1))
#
#with open("slalib_hip_map.txt", "w") as f:
# f.write("# Apparent RA DEC for J2000.0 in degrees.\n")
# for r, d in zip(ra, dec):
# s = "%14.9f %14.9f\n"
# f.write(s % (r, d))
# sla_aop
# Convert apparent to observed place.
tab['pma'] = np.radians(tab['pma'] / 3600.0) / 100.0
tab['pmd'] = np.radians(tab['pmd'] / 3600.0) / 100.0
utc = slalib.sla_caldj(2010, 1, 1)[0]
tt = slalib.sla_dtt(utc) / 86400.0 + utc
dut = 1.4823561643834426 # from TPM.
aob = np.zeros((len(tab['raj2']), ), dtype=np.float64)
zob = aob.copy()
hob = aob.copy()
dob = aob.copy()
rob = aob.copy()
lon = np.radians(-111.598333)
lat = np.radians(31.956389)
for j, i in enumerate(tab):
r1, d1 = slalib.sla_map(i['raj2'], i['decj2'], i['pma'], i['pmd'], i['px'],
0.0, 2000.0, tt)
aob[j], zob[j], hob[j], dob[j], rob[j] = \
slalib.sla_aop(r1, d1, utc, dut, lon, lat, 2093.093, 0.0, 0.0,
def _convert_coordinates(self, lat, long, ra_ref, dec_ref, date, time):
""" Accurate conversion from equatorial coordiantes (RA, DEC) to Spherical (TH,PH) coordinates.
The code uses the pyslalib library for a number of functions from the SLALIB Fortran library converted to Python.
:param lat: latitude (decimal degrees)
:param long: longitude (decimal degrees)
:param ra_ref: RA(J2000) (decimal hours)
:param dec_ref: Dec(J2000) (decimal degrees)
:param date: vector date [iyear, imonth, iday]
:param time: vector time [ihour imin isec]
:return: [theta, pi]: Theta and Phi angles (degrees)
"""
const_2pi = 2.0 * math.pi
d2r = math.pi / 180
r2d = 180 / math.pi
# Conversion factor seconds of time to days
const_st2day = 1.0/(24 * 3600)
# Specify latitude and longitude (radians)
lat *= d2r
long *= d2r
# Specify catalogued position (J2000 coordinates, radians)
ra_ref = ra_ref * 15 * d2r
dec_ref *= d2r
# Specify current time and date %
isec = time[2]
imin = time[1]
ihour = time[0]
iday = date[2]
imonth = date[1]
iyear = date[0]
# Convert current UTC to Modified Julian date
djm, j1 = slalib.sla_cldj(iyear, imonth, iday)
fdutc, j2 = slalib.sla_dtf2d(ihour, imin, isec)
djutc = djm + fdutc
# Calculate Greenwich Mean Sidereal Time from MJD
gmst1 = slalib.sla_gmst(djutc)
# Add longitude and Equation of Equinoxes for Local Apparent ST
djtt = djutc + slalib.sla_dtt(djutc)*const_st2day
last = gmst1 + long + slalib.sla_eqeqx(djtt)
if last < 0.0:
last += const_2pi
# Convert catalogued position to apparent RA, Dec at current date
pr = 0.e0
pd = 0.e0
px = 0.e0
rv = 0.e0
eq = 2000.0e0
[raobs, decobs] = slalib.sla_map(ra_ref, dec_ref, pr, pd, px, rv, eq, djutc)
# Get Hour Angle and Declination
ha = last - raobs
if ha < -math.pi:
ha += const_2pi
if ha > math.pi:
ha -= const_2pi
dec = decobs
# Convert to Azimuth and Elevation
azim, elev = slalib.sla_de2h(ha, dec, lat)
theta = (90 - elev * r2d).real
phi = (azim * r2d).real
return [theta, phi]
