10
PNSW name changed to TERCEL (TERrestrial-to-CELestial transformation). Input argument
changed to UT1 Julian date in pair of double-precision words.
CELPOL input corrections to pole position can now be either (X, Y) or (
, ), the choice
specified by a new input parameter. Units must now be in milliarcseconds.
SPIN no longer specifically associated with sidereal time. Now applies a rotation about the current
z-axis, with angle expressed in degrees.
SUNFLD replaced by GRVDEF, a more general subroutine that evaluates the gravitational
deflection of light due to several solar system bodies.
All of the high-level subroutines (PLACE, APSTAR, APPLAN, etc.) now assume that they are
working with ICRS data; this goes for the input RA, Dec, and proper motion components for the
star routines and the position and velocity vectors obtained from SOLSYS (e.g., from DE-405) in
both the star and planet routines. VPSTAR, LPSTAR, VPPLAN, LPPLAN, ASSTAR, ASPLAN,
and MPSTAR produce output positions in the ICRS.
Significant Internal Changes to Code
Common error conditions will now generate error messages sent to unit=* (standard output, usually the
terminal screen). Each error message always begins with the name of the subroutine that produced
it, and is a plain-English description of the problem.
All subroutines that need astronomical constants now call ASTCON to obtain the values they need on
their first call. Those values are SAVEd for use on subsequent calls. Those values are:
SPEED OF LIGHT IN METERS/SECOND -- A DEFINING PHYSICAL CONSTANT:
c = 299,792,458
LIGHT-TIME FOR ONE ASTRONOMICAL UNIT IN TDB SECONDS, FROM DE-405:
a(sec) = 499.0047838061
SPEED OF LIGHT IN AU/DAY:
c(AU/day) = 86400 / a(sec)
LENGTH OF ASTRONOMICAL UNIT IN METERS:
a = a(sec)
×
c
HELIOCENTRIC GRAVITATIONAL CONSTANT IN METERS
3
/SECOND
2
, FROM DE-405:
GS = 1.32712440017987
× 10
20
GEOCENTRIC GRAVITATIONAL CONSTANT IN METERS
3
/SECOND
2
, FROM DE-405:
GM = 3.98600433
× 10
14
EQUATORIAL RADIUS OF EARTH IN METERS, FROM IERS CONVENTIONS (2003):
r
= 6,378,136.6
FLATTENING FACTOR OF EARTH, FROM IERS CONVENTIONS (2003):
f = 1 / 298.25642
NOMINAL MEAN ROTATIONAL ANGULAR VELOCITY OF EARTH, IN RADIANS/SECOND, FROM
IERS CONVENTIONS (2003):
= 7.2921150
× 10
-5
RECIPROCAL MASSES (SUN MASS/BODY MASS) FOR SOLAR SYSTEM BODIES
SUN = 1
MOON = 27,068,700.387534
MERCURY = 6,023,600
VENUS = 408,523.71
