pg_sphere--1.1.5beta0gavo--1.1.5beta2gavo.sql\

pg_sphere--1.1.5beta2gavo--1.1.5beta4gavo.sql\

pg_sphere--1.1.5beta4gavo--1.2.0.sql\

pg_sphere--1.1.5beta4gavo--1.2.0.sql\

pg_sphere--1.2.0--1.2.1.sql

DOCS = README.pg_sphere COPYRIGHT.pg_sphere

cat$^>$@

ifeq ($(has_parallel), n)

sed -i -e '/PARALLEL/d' $@# version $(pg_version) does not have support for PARALLEL

pg_sphere--1.2.0-1.2.1.sql: pgs_epochprop.sql.in

cat upgrade_scripts/$@.in$^>$@

pg_sphere--1.2.0--1.2.1.sql: pgs_moc_geo_casts.sql.in

pg_sphere--1.2.0--1.2.1.sql: pgs_moc_geo_casts.sql.in pgs_epochprop.sql.in

cat$^>$@

ifeq ($(has_parallel), n)

sed -i -e '/PARALLEL/d' $@# version $(pg_version) does not have support for PARALLEL

</example>

</sect2>

<sect2 id="funcs.epochprop">

<title>

Epoch propagation

</title>

<sect3 id="funcs.epochprop.full">

<title>6-Parameter Epoch Propagation</title>

<funcsynopsis>

<funcprototype>

<funcdef><type>double precision[6]</type>

<function>epoch_prop</function></funcdef>

<paramdef>spoint <parameter>pos</parameter></paramdef>

<paramdef>double precision <parameter>parallax</parameter></paramdef>

<paramdef>double precision <parameter>pm_long</parameter></paramdef>

<paramdef>double precision <parameter>pm_lat</parameter></paramdef>

<paramdef>double precision <parameter>radial_velocity</parameter></paramdef>

<paramdef>double precision <parameter>delta_t</parameter></paramdef>

</funcprototype>

</funcsynopsis>

<para>

Propagates a spherical phase vector in time (in particular,

applies proper motion to positions)

</para>

<para>

Following both pg_sphere and, where missing, astronomical

conventions makes units somewhat eclectic here; pm_long and pm_lat

need to be in rad/yr, whereas parallax is in mas, and

radial_velocity in km/s. The time difference must be in

(Julian) years.

</para>

<para>

This function returns a 6-array of [long, lat, parallax,

pm_long, pm_lat, radial_velocity] of the corresponding values

delta_t years after the reference epoch for the original position.

As in the function arguments, long and lat are in rad, pm_lon and

pm_lat are in rad/yr, parallax is in mas, and radial_velocity is

in km/s. If you are only interested in the position, consider

the epoch_prop_pos functions below that have a somewhat less

contorted signature.

</para>

<para>

It is an error to have either pos or delta_t NULL. For all

other arguments, NULLs are turned into 0s, except for parallax,

where some very small default is put in. In that case,

both parallax and radial_velocity will be NULL in the output

array.

</para>

<para>

This uses the rigorous method derived in "The Hipparcos and Tycho

Catalogues", ESA Special Publication 1200 (1997), p 94f. It does

not take into account relativistic effects, and it also does not

account for secular aberration.

</para>

<example>

<title>Propagating Barnard's star into the past</title>

<programlisting><![CDATA[

SELECT

to_char(DEGREES(tp[1]), '999D9999999999'),

to_char(DEGREES(tp[2]), '999D9999999999'),

to_char(tp[3], '999D999'),

to_char(DEGREES(tp[4])*3.6e6, '999D999'),

to_char(DEGREES(tp[5])*3.6e6, '99999D999'),

to_char(tp[6], '999D999')

FROM (

SELECT epoch_prop(

spoint(radians(269.45207695), radians(4.693364966)), 546.9759,

RADIANS(-801.551/3.6e6), RADIANS(10362/3.6e6), -110,

-100) AS tp) AS q;

to_char | to_char | to_char | to_char | to_char | to_char

-----------------+-----------------+----------+----------+------------+----------

269.4742714391 | 4.4072939987 | 543.624 | -791.442 | 10235.412 | -110.450

]]></programlisting>

</example>

</sect3>

<sect3>

<title>Epoch Propagation of Positions Only</title>

<funcsynopsis>

<funcprototype>

<funcdef><type>spoint</type>

<function>epoch_prop_pos</function></funcdef>

<paramdef>spoint <parameter>pos</parameter></paramdef>

<paramdef>double precision <parameter>parallax</parameter></paramdef>

<paramdef>double precision <parameter>pm_long</parameter></paramdef>

<paramdef>double precision <parameter>pm_lat</parameter></paramdef>

<paramdef>double precision <parameter>radial_velocity</parameter></paramdef>

<paramdef>double precision <parameter>delta_t</parameter></paramdef>

</funcprototype>

</funcsynopsis>

<funcsynopsis>

<funcprototype>

<funcdef><type>spoint</type>

<function>epoch_prop_pos</function></funcdef>

<paramdef>spoint <parameter>pos</parameter></paramdef>

<paramdef>double precision <parameter>pm_long</parameter></paramdef>

<paramdef>double precision <parameter>pm_lat</parameter></paramdef>

<paramdef>double precision <parameter>delta_t</parameter></paramdef>

</funcprototype>

</funcsynopsis>

<para>

These are simplified versions of epoch_prop returning only spoints;

the propagated values for the other coordinates are discarded

(but still internallay computed; these functions do not

run any faster than epoch_prop itself).

</para>

<para>

As with epoch_prop itself, missing values (except for pos and

delta_t) are substituted by 0 (or a very small value in the

case of parallax).

</para>

<example>

<title>Barnard's star, position and proper motion</title>

<programlisting><![CDATA[

SELECT epoch_prop_pos(

spoint(radians(269.45207695), radians(4.693364966)),

RADIANS(-801.551/3.6e6), RADIANS(10362/3.6e6),

20) AS tp;

tp

-----------------------------------------

(4.70274793061952 , 0.0829193989380876)

]]></programlisting>

</example>

</sect3>

</sect2>

</sect1>