def get_cip(jd1, jd2):
"""
Find the X, Y coordinates of the CIP and the CIO locator, s.
Parameters
----------
jd1 : float or `np.ndarray`
First part of two part Julian date (TDB)
jd2 : float or `np.ndarray`
Second part of two part Julian date (TDB)
Returns
--------
x : float or `np.ndarray`
x coordinate of the CIP
y : float or `np.ndarray`
y coordinate of the CIP
s : float or `np.ndarray`
CIO locator, s
"""
# classical NPB matrix, IAU 2006/2000A
rpnb = erfa.pnm06a(jd1, jd2)
# CIP X, Y coordinates from array
x, y = erfa.bpn2xy(rpnb)
# CIO locator, s
s = erfa.s06(jd1, jd2, x, y)
return x, y, s
# SOFA heliocentric Earth ephemeris.
pvh, pvb = erfa.epv00(tt1, tt2)
# JPL DE405 barycentric Earth ephemeris.
pvb = np.array(
[
(
(-0.9741704366519668, -0.2115201000882231, -0.0917583114068277),
(0.0036436589347388, -0.0154287318503146, -0.0066892203821059),
)
]
)
# era 2000A CIP.
r = erfa.pnm00a(tt1, tt2)
x, y = erfa.bpn2xy(r)
# Apply IERS corrections.
x += dx
y += dy
# SOFA CIO locator. */
s = erfa.s06(tt1, tt2, x, y)
# Populate the context.
astrom = erfa.apci(tt1, tt2, pvb, pvh, x, y, s)
# Carry out the transformation and report the results.
ri, di = erfa.atciq(rc, dc, pr, pd, px, rv, astrom)
reprd("ICRS -> CIRS (JPL, IERS):", ri, di)
# The same but with Saturn then Jupiter then Sun light deflection.
aob, zob, hob, dob, rob, eo = erfa.atco13(rc, dc, pr, pd, px, rv, utc1, utc2,
dut1, elong, phi, hm, xp, yp, phpa,
tc, rh, wl)
reprd("ICRS -> observed:", rob, dob)
# ICRS to CIRS using some user-supplied parameters.
# SOFA heliocentric Earth ephemeris.
pvh, pvb = erfa.epv00(tt1, tt2)
# JPL DE405 barycentric Earth ephemeris.
pvb = ((-0.9741704366519668, -0.2115201000882231, -0.0917583114068277),
(0.0036436589347388, -0.0154287318503146, -0.0066892203821059))
# era 2000A CIP.
r = erfa.pnm00a(tt1, tt2)
x, y = erfa.bpn2xy(r)
# Apply IERS corrections.
x += dx
y += dy
# SOFA CIO locator. */
s = erfa.s06(tt1, tt2, x, y)
# Populate the context.
astrom = erfa.apci(tt1, tt2, pvb, pvh[0], x, y, s)
# Carry out the transformation and report the results.
ri, di = erfa.atciq(rc, dc, pr, pd, px, rv, *astrom)
reprd("ICRS -> CIRS (JPL, IERS):", ri, di)
# The same but with Saturn then Jupiter then Sun light deflection.