SLA_MAP - Mean to Apparent

From d54fe7c1f704a63824c5bfa0ece65245572e9b27 Mon Sep 17 00:00:00 2001 From: Joseph Hunkeler Date: Wed, 4 Mar 2015 21:21:30 -0500 Subject: Initial commit --- src/slalib/sun67.htx/node126.html | 157 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 157 insertions(+) create mode 100644 src/slalib/sun67.htx/node126.html (limited to 'src/slalib/sun67.htx/node126.html') diff --git a/src/slalib/sun67.htx/node126.html b/src/slalib/sun67.htx/node126.html new file mode 100644 index 0000000..abe5fb6 --- /dev/null +++ b/src/slalib/sun67.htx/node126.html @@ -0,0 +1,157 @@ + + + + +SLA_MAP - Mean to Apparent + + + + + + + + + + + + +

+ +

+
+ Next: SLA_MAPPA - Mean to Apparent Parameters +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_M2AV - Rotation Matrix to Axial Vector +

SLA_MAP - Mean to Apparent + +

ACTION: +: Transform star $[\,\alpha,\delta\,]$ from mean place to geocentric apparent. +The reference frames and timescales used are post IAU 1976. +
CALL: +: CALL sla_MAP (RM, DM, PR, PD, PX, RV, EQ, DATE, RA, DA) +

GIVEN: +

+
+ + + + + + + + + + + + + + + + + + + + + + + + + +

RM,DM	D	mean $[\,\alpha,\delta\,]$ (radians)
PR,PD	D	proper motions: $[\,\alpha,\delta\,]$ changes per Julian year
PX	D	parallax (arcsec)
RV	D	radial velocity (km s^-1, +ve if receding)
EQ	D	epoch and equinox of star data (Julian)
DATE	D	TDB for apparent place (JD-2400000.5)

RETURNED: +

+
+ + + + + +

RA,DA	D	apparent $[\,\alpha,\delta\,]$ (radians)

NOTES: +

1. +: EQ is the Julian epoch specifying both the reference +frame and the epoch of the position - usually 2000. +For positions where the epoch and equinox are + different, use the routine sla_PM to apply proper + motion corrections before using this routine. +
2. +: The distinction between the required TDB and TT is + always negligible. Moreover, for all but the most + critical applications UTC is adequate. +
3. +: The $\alpha$ proper motions are $\dot{\alpha}$ rather than + $\dot{\alpha}\cos\delta$ , and are per year rather than per century. +
4. +: This routine may be wasteful for some applications + because it recomputes the Earth position/velocity and + the precession/nutation matrix each time, and because + it allows for parallax and proper motion. Where + multiple transformations are to be carried out for one + epoch, a faster method is to call the sla_MAPPA routine + once and then either the sla_MAPQK routine (which includes + parallax and proper motion) or sla_MAPQKZ (which assumes + zero parallax and FK5 proper motion). +

REFERENCES: +

1. +: 1984 Astronomical Almanac, pp B39-B41. +
2. +: Lederle & Schwan, 1984. Astr.Astrophys. 134, 1-6. +

+ +

+
+ Next: SLA_MAPPA - Mean to Apparent Parameters +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_M2AV - Rotation Matrix to Axial Vector +

+SLALIB --- Positional Astronomy Library
Starlink User Note 67
P. T. Wallace
12 October 1999
E-mail:ptw@star.rl.ac.uk +

+ + -- cgit