9

GRVDEF replacement for SUNFLD that supervises the evaluation of gravitational deflection of light

due to the Sun, Jupiter, and other solar system bodies. Calls new subroutine GRVD to do the

deflection calculation for each body.

GEOPOS called from PLACE to compute the geocentric position and velocity vectors of an observer

on or above the surface of the Earth.

LITTIM called from PLACE to antedate the position of a solar system body for light-time.

LIMANG evaluates where an observed object is with respect to the Earth's limb (horizon), given the

geocentric position vectors of the observer and the object. PLACE calls LIMANG for the

topocentric cases in deciding whether to include the gravitational deflection of light due to the

Earth itself.

CEORA returns the value of the true right ascension of the CEO for a given TDB Julian date.

CEORAI

- returns the value of the ICRS right ascension of the CEO for a given TDB Julian date.

CEORD

- for high-accuracy calculations, reads and returns a set of values of the ICRS right ascension

of the CEO, near a given TDB Julian date, from an external file (either formatted sequential or

binary direct-access).

CEOFIL allows the specification of the external file of CEO right ascensions that CEORD reads.

CEOBAS

- returns orthonormal basis vectors for non-rotating equatorial (intermediate) system.

SETMOD sets method/accuracy mode for Earth rotation calculations.

GETMOD retrieves method/accuracy mode for Earth rotation calculations.

EQINOX specifies that equinox-based method is to be used for Earth rotation calculations.

CEOTEO specifies that the CEO-based method is to be used for Earth rotation calculations.

HIACC specifies that high-accuracy (~1 µas) algorithms are to be used for Earth rotation

calculations.

LOACC specifies that low-accuracy (~0.1 mas) algorithms are to be used for Earth rotation

calculations.

RESUME reverts to method/accuracy mode used prior to latest change (by one of the above

subroutines).

Changes to Existing (NOVAS Version F2.0) Calling Sequences

APSTAR, VPSTAR, ASSTAR, CATRAN, GETHIP, VECTRS proper motion units (in both RA and

Dec) changed to milliarcseconds/year (pm in RA includes cos

factor), parallax units changed to

milliarcseconds.

TPSTAR, TPPLAN, LPSTAR, LPPLAN the user's option to specify the input time argument as

apparent sidereal time in hours is now discouraged; specifying the corresponding UT1 Julian date

is now recommended. Sidereal time input is still supported but might not be in future NOVAS

releases.

PRECES, CATRAN one of the input epochs must now be 2451545.0 (J2000.0). Can no longer do

two arbitrary epochs (the new precession expressions are not as flexible as Newcomb's or

Lieske's).

CATRAN has two new transformation options: IT=4 rotates data from the dynamical equator and

equinox of J2000.0 to the ICRS and IT=5 does the opposite rotation.

WOBBLE Julian date argument added.