SacredStar

This project implements an easy interface to conduct astrological research.

It can be used to easily cast a chart and:

• Run house calculations
• Do birthtime rectification
• Calculate different zodiacal positions
• Supports Vedic varga charts (up to D60)
• Calculates Vimshottari dashas
• Supports traditional and modern planets
• Supports sidereal and tropical charts
• Runs on Moshier's analytical ephemeris (swemmoon.c for the moon, swemplan.c for the planets), so no ephemeris data files are read at runtime

Applications using SacredStar

• Astrologos

Installation

Add the library to your Go project

go get github.com/afjoseph/sacredstar

This library uses native code, so you'll need to run CGO=1 when building

Also, you'll need to set up SwissEph library. See below

Setting up Swisseph

This project uses Just task runner to run project commands. You can install it on an OSX machine with brew install just. See the project for other installation instructions.

This project uses the swisseph library and header files for calculation of planet and star positions.

All the required files are bundled in ./ext/swisseph/.

In most cases, running just build-and-symlink-swisseph should be enough to set this project to work on your development machine.

Note that only the library and headers are needed: swisseph's ephemeris data files are never read, since every calculation passes SEFLG_MOSEPH. See "Ephemeris backend" below.

Ephemeris backend

Every swe_calc_ut call passes SEFLG_MOSEPH, which selects Moshier's analytical series (swemmoon.c for the moon, swemplan.c for the planets) instead of the compressed JPL data files (*.se1).

• Nothing is read off disk, so there is no ephemeris path to configure and nothing to ship next to your binary
• Drift against the .se1 files is well under an arcsecond for the bodies this library computes (Sun through Pluto, plus the true node), i.e., far below any usable orb
• Valid range is roughly 3000 BC to 3000 AD
• Bodies Moshier doesn't cover (asteroids like Chiron) would need SEFLG_SWIEPH and the data files

Explanation

This is the directory breakdown of swisseph

• ./ext/swisseph
  • the swisseph library from astro.com
  • ./original_project contains the original swisseph source files, downloaded verbatim from https://www.astro.com/ftp/swisseph/src/
    • crudely with wget -r --no-parent https://www.astro.com/ftp/swisseph/src/
  • ./include contains the used header files
    • Those are copy-pasted from ./original_project
  • ./lib
    • Contains the generated libswe.a file
    • libswe.a was generated with just build-and-symlink-swisseph

We use pkg-config to inform cgo (the FFI responsible for calling C code from Go) where the swisseph libraries and header files are located. We're doing this using pkg-config, as opposed to a simple relative path, to maintain uniformity between building on a developer machine (e.g., using OSX) and a production instance (e.g., running a linux distro or using Docker with a linux distro).

If you look at the header of ./backend/swisseph/chart/chart.go, you'll find this:

package chart

import (
	// #cgo pkg-config: swisseph
	// #include <stdio.h>
	// #include <errno.h>
	// #include "swephexp.h"
	"C"
)

This just means we're telling cgo to use pkg-config --libs --cflags during compilation. The swisseph.pc file is located in ./backend/ext/swisseph/. You'll need to symlink it to your machine before backend development can start. You can do that with just build-and-symlink-swisseph. The commands were configured to work successfully on an OSX machine, but you might need to tweak it for your system.

Another reason we're doing this is because libswe.a (i.e., the main swisseph library) will use a different architecture depending on the machine it was built with (e.g., arm64 on an OSX machine with M1+ chips, and x86_64 on a production instance running a linux machine).

Setting up SwissEph on a Remote Machine

After building your project, you'd wanna deploy it somewhere. SwissEph needs to be symlinked properly on your remote machine.

For Ansible deployments, do something like this to copy, build and symlink swisseph on your remote machine

- name: Copy swisseph directory to the remote machine
  copy:
    src: sacredstar/ext/swisseph
    dest: /home/myuser/app
    mode: '0755'

- name: Set up Swisseph libraries and links
  vars:
    # Remember to
    swisseph_path: /home/myuser/app/swisseph
  shell: |
    rm -rf /usr/local/lib/pkgconfig/swisseph.pc
    rm -rf /usr/local/include/swisseph
    rm -rf /usr/local/lib/swisseph
    (cd {{ swisseph_path }}/original_project && make clean libswe.a)
    cp {{ swisseph_path }}/original_project/libswe.a {{ swisseph_path }}/lib/libswe.a
    mkdir -p /usr/local/lib/pkgconfig
    ln -sf {{ swisseph_path }}/swisseph.pc /usr/local/lib/pkgconfig/swisseph.pc
    ln -sf {{ swisseph_path }}/include /usr/local/include/swisseph
    ln -sf {{ swisseph_path }}/lib /usr/local/lib/swisseph
  args:
    executable: /bin/bash

For Docker builds, the Docker image needs to copy, build and symlink SwissEph

    # Set up Swisseph libraries
    RUN rm -rf /usr/local/lib/pkgconfig/swisseph.pc && \
        rm -rf /usr/local/include/swisseph && \
        rm -rf /usr/local/lib/swisseph
    # Copy and build Swisseph
    COPY ./ext/swisseph /swisseph
    RUN cd /swisseph/original_project && make clean libswe.a && \
        cp /swisseph/original_project/libswe.a /swisseph/lib/libswe.a && \
        mkdir -p /usr/local/lib/pkgconfig && \
        ln -sf /swisseph/swisseph.pc /usr/local/lib/pkgconfig/swisseph.pc && \
        ln -sf /swisseph/include /usr/local/include/swisseph && \
        ln -sf /swisseph/lib /usr/local/lib/swisseph

Usage

For example, here is William Lilly's "Considerations Before Judgement" implemented with SacredStar

    package main

    import (
        "time"

        "github.com/afjoseph/sacredstar/chart"
        "github.com/afjoseph/sacredstar/house"
        "github.com/afjoseph/sacredstar/pointid"
        "github.com/afjoseph/sacredstar/rulership"
        "github.com/afjoseph/sacredstar/timeandzone"
        "github.com/afjoseph/sacredstar/wrapper"
        "github.com/afjoseph/sacredstar/zodiacalpos"
    )

    func main() {
        // Init wrapper
        mysacredstar := wrapper.New()
        defer mysacredstar.Close()

        chartTime := time.Date(2025, 1, 9, 10, 21, 0, 0, time.UTC)
        currTimeInJulian := mysacredstar.GoTimeToJulianDay(date)
        lon, lat, _ := timeandzone.Zones.GetLonLatFromTimezone("Europe/Zurich")
        myChart, _ := chart.NewChartFromJulianDay(
            mysacredstar,
            currTimeInJulian,
            lon, lat,
            chart.TropicalChartType,
            // Or pointid.ModernPlanets, or pointid.VedicPlanets
            pointid.TraditionalPlanets,
        )

        // Ascendant too early / too late
        ascendant := myChart.MustGetPoint(pointid.ASC)
        if ascendant.ZodiacalPos.Degrees < 4 {
            ...
        }
        if ascendant.ZodiacalPos.Degrees > 26 {
            ...
        }

        // Moon too late
        moon := myChart.MustGetPoint(pointid.Moon)
        if moon.ZodiacalPos.Degrees > 26 {
            ...
        }

        // Seventh house afflicted
        seventhHouseRuler := rulership.MustFindRuler(myChart, house.House7)
        seventhHouseRulerStrength, s, reasons := rulership.GetStrength(
            myChart,
            seventhHouseRuler,
        )
        if seventhHouseRulerStrength == rulership.StrengthWeak {
            ...
        }

        // Ascendant ruler combust
        ascendantRuler := rulership.MustFindRuler(myChart, house.House1)
        sunPoint := myChart.MustGetPoint(pointid.Sun)
        asp := ascendantRuler.ZodiacalPos.GetAspect(sunPoint.ZodiacalPos)
        if asp != nil && asp.Type == zodiacalpos.AspectType_Conjunction {
            ...
        }

        // Saturn on ascendant or descendant
        // This means Saturn is conjunct/opposed with the ascendant
        saturn := myChart.MustGetPoint(pointid.Saturn)
        asp = saturn.ZodiacalPos.GetAspect(ascendant.ZodiacalPos)
        if asp != nil &&
            (asp.Type == zodiacalpos.AspectType_Conjunction ||
                asp.Type == zodiacalpos.AspectType_Opposition) {
            ...
        }
    }

Testing

Run tests with just test. This is a really good way to see if your machine's integration is sound.