Aphelion and Perihelion

[ABer]

Hi there - I am wondering whether there is function to work out the longitude of the points of aphelion (most distant approach to the Sun) and perhelion (closest approach to the Sun) for each of the main planets within Astrobasic. This would be useful for a heliocentric module I am working on.

Thanks. Ed

[Jean]

Hi Ed,

it seems this is done by the SE function swe_nod_aps_ut(), here https://www.astro.com/swisseph/swephprg.htm#_Toc78973575

Ab has node()
Syntax: real node(char planet, real jd, char helio, real result[2]);
Action: returns ascending and descending nodes of 'planet' for julian day 'jd' in result[], set 'helio' for heliocentric.

I could make it return more values, what do you need?

[ABer]

Hi Jean - if you have some time it would be really helpful to have the degree in longitude for the heliocentric position of the aphelion and perihelion of each of the main planets (Sun-Chiron). Philip Sedgwick uses these points in his heliocentric approach (The Sun at the Center: A Primer of Heliocentric Astrology). I have attached a screenshot of the module as work in progress.

Thanks. Ed

[Jean]

Just published an update for node()

Syntax: real node(char planet, real jd, char helio, real result[4]);
Action: returns ascending and descending nodes, perihelion and aphelion of 'planet' for julian day 'jd' in result[], set 'helio' for heliocentric.

Duh, it was not necessary, it's already in there, look at the help for getplanet(), the last numbers.

[ABer]

Thanks Jean - I'd racked my brains about that but forgot about getplanet(). I appreciate your efforts with this. I will take a look at both options. I should be able to press on with the module now.

Ed

[ABer]

For reference:

Perihelion is found using planetnumber 89-97. Aphelion is found using planetnumber 98-106.

From the Astrobasic Helpfiles:

getplanet

Syntax: getplanet(int planetnumber, int horoscopenumber, real result[6]);

Action: calculates a planet or body. Some results rely on a horoscope being calculated, for others only sethoroscopetime is needed. The array result will have these values:

0 longitude
1 latitude
2 speed (degree/day)
3 declination
4 rectascension
5 radius (astronomical units)

Planetnumbers are:
-2 Armc
-1 Ecliptica
0 Sun
1 Moon
2 Mercury
3 Venus
4 Mars
5 Jupiter
6 Saturn
7 Uranus
8 Neptune
9 Pluto
10 Node (type currently defined in options general)
11 Chiron
12 Lilith / black moon
13 Pars
14 Ascendant
15 mc
16 Vertex
17 Mean Node
18 True Node
19 South Node
20 True Lilith
21 Pholus
22 Ceres
23 Pallas
24 Juno
25 Vesta
26 Nessus
27 Huya
28 Makemake
29 Haumea
30 Eris
31 Ixion
32 Orcus
33 Quaoar
34 Sedna
35 Varuna
36 Selena
37 Cupido
38 Hades
39 Zeus
40 Kronos
41 Apollon
42 Admetos
43 Vulkanus
44 Poseidon
45 Moo node Asc
46 Mer node Asc
47 Ven node Asc
48 Mar node Asc
49 Jup node Asc
50 Sat node Asc
51 Ura node Asc
52 Nep node Asc
53 Plu node Asc
54 Moo node Des
55 Mer node Des
56 Ven node Des
57 Mar node Des
58 Jup node Des
59 Sat node Des
60 Ura node Des
61 Nep node Des
62 Plu node Des
63 Dragon
64 Beast
65 Corr Lilith
66 Priapus
67 Corr Priapus
68 Black Sun
69 Diamond
70 Vulkanus
71 Persephone
72 Ecliptica
73-87 asteroid nodes
88 chiron node
89-97 moon - pluto perihelium
98-106 moon - pluto aphelium