thesky_comets Module Reference

Procedures for comets. More...

Functions/Subroutines
subroutine	cometxyz (t1, comid, x, y, z)
	Calculate heliocentric xyz coordinates for comet com at t1 (in J.mill DT). Usually called by cometgc() below.
subroutine	cometgc (t, t0, comid, r, l, b, d)
	Calc geocentric lbr coordinates for comet com at t1 (in Julian millennia Dynamical Time)

Detailed Description

Procedures for comets.

Function/Subroutine Documentation

cometgc()

subroutine thesky_comets::cometgc	(	real(double), intent(in)	t,
		real(double), intent(in)	t0,
		integer, intent(in)	comid,
		real(double), intent(out)	r,
		real(double), intent(out)	l,
		real(double), intent(out)	b,
		real(double), intent(out)	d )

Calc geocentric lbr coordinates for comet com at t1 (in Julian millennia Dynamical Time)

Note

This a computational detour to allow correction for aberration, fk5 and nutation in planet_position (and keep overview there)

Parameters

t	Apparent time (taking light time into account) in Julian millennia Dynamical Time
t0	True time in Julian millennia DT
comID	Comet ID
r	Apparent heliocentric distance of comet (output). Note: r=0 if calculation diverged!
l	Apparent geocentric ecliptic longitude of comet (output)
b	Apparent geocentric ecliptic latitude of comet (output)
d	Apparent geocentric distance of comet (output)

Definition at line 264 of file comets.f90.

References thesky_cometdata::comepoche, cometxyz(), thesky_coordinates::ecl_spher_2_eq_rect(), thesky_coordinates::eq_2_ecl(), thesky_coordinates::fk5(), thesky_nutation::nutation(), thesky_coordinates::precess_xyz(), and thesky_vsop::vsop87d_lbr().

Referenced by thesky_visibility::comet_invisible(), and thesky_planets::planet_position().

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cometxyz()

subroutine thesky_comets::cometxyz	(	real(double), intent(in)	t1,
		integer, intent(in)	comid,
		real(double), intent(out)	x,
		real(double), intent(out)	y,
		real(double), intent(out)	z )

Calculate heliocentric xyz coordinates for comet com at t1 (in J.mill DT). Usually called by cometgc() below.

Parameters

t1	Time in Julian millennia DT
comID	Comet ID
x	Heliocentric x coordinate (output)
y	Heliocentric y coordinate (output)
z	Heliocentric z coordinate (output)

Note

x=y=z=0 is returned if the calculation does not converge.

See also

Meeus, Astronomical Algorithms, 1998, Ch. 30, 33-35. Equation and page numbers refer to this book.

Todo

Use "hyperbolic method" for 0.98 < e < 1 as well? - see CHECK

Definition at line 45 of file comets.f90.

References thesky_cometdata::comepoche, thesky_cometdata::cometelems, thesky_cometdata::cometnames, thesky_nutation::nutation(), and thesky_constants::thesky_verbosity.

Referenced by cometgc().

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