How to get Sector and Vector Coords of star?

Post Reply
CMDR ARGHouse
Posts: 16
Joined: Mon Feb 11, 2019 1:34 pm
Location: Australia

How to get Sector and Vector Coords of star?

Post by CMDR ARGHouse » Thu Nov 26, 2020 11:08 am

Hi, been doing some research into how pioneer handles sectors and placing of stars and I'm still stumped by how sector and vector co-ordinates are calculated?

For example. Castor in the bright stars file is:
(5,2,3,v(0.012,0.194,0.404))

while out of pioneer, it's RA is 07h 34m 35.863s, DEC is +31° 53′ 17.79″ and is about 51 LY away from Sol. I'm am wondering how Sector and Vector Coordinates are calculated from astrometric data?

nozmajner
Posts: 1029
Joined: Mon Jul 01, 2013 3:25 pm
Location: Budapest HU

Re: How to get Sector and Vector Coords of star?

Post by nozmajner » Thu Nov 26, 2020 11:26 am

The numbers between the parenthesis are subcoordinates let's say, where they lie inside the sector. Sectors are 8*8*8 ly cubes.
I once figured out how to convert RA coordinates to our cartesian coordinates, but I have to dig that up.

nozmajner
Posts: 1029
Joined: Mon Jul 01, 2013 3:25 pm
Location: Budapest HU

Re: How to get Sector and Vector Coords of star?

Post by nozmajner » Thu Nov 26, 2020 12:41 pm

I just found this, it might be useful: Coordinate converter

CMDR ARGHouse
Posts: 16
Joined: Mon Feb 11, 2019 1:34 pm
Location: Australia

Re: How to get Sector and Vector Coords of star?

Post by CMDR ARGHouse » Sat Nov 28, 2020 4:08 am

https://astronomy.stackexchange.com/que ... h-distance
I found something, I've just got to brush off my trig knowledge.

sturnclaw
Posts: 49
Joined: Tue Sep 18, 2018 12:20 am

Re: How to get Sector and Vector Coords of star?

Post by sturnclaw » Tue Dec 01, 2020 4:28 am

So, I'm not the person who originally set the coordinates of the stars, but here are a few fundamental points about our coordinate system:

- Sol (0, 0, 0) is the center of the coordinate system.
- The density of the galactic plane varies uniformly with respect to abs(sector.Z), indicating that the Z axis is defined as normal to the galactic plane.
- Sagittarius A* is located at (-3125, 0, 0), so the X axis of the coordinate system is directly aligned with the exact galactic center.

Therefore, I can at least semi-confidently say that our galaxy is addressed with a coordinate system exactly like so:
Image

Sol is at sector coordinate (0, 0, 0), with the negative X axis of the sector coordinate system pointed towards 0 degrees in that image and the positive Y axis of the coordinate system pointed towards 90 degrees. Converting from Right Ascension+Declination to Galactic Cartesian Coordinates is accomplished by following https://en.wikipedia.org/wiki/Galactic_ ... oordinates to get 'l' and 'b', then with the link you posted to convert spherical coordinates into Cartesian.

Be wary to make sure the galactic longitude of 0 gives you a cartesian coordinate in the negative X direction, as we don't follow the "standard" axis convention for galactic *or* spherical coordinates.

Gliese852
Posts: 5
Joined: Sat Jun 06, 2020 12:12 pm

Re: How to get Sector and Vector Coords of star?

Post by Gliese852 » Thu Dec 03, 2020 12:23 pm

I would like to point out a couple of things:
1. In Pioneer, there is no translation from the equatorial coordinate system to the galactic one, all custom systems, except for the Sagittarius A*, are inserted into the galaxy directly in the equatorial one. (see viewtopic.php?f=3&t=302&start=20)
2. Translation from one spherical coordinate system to another is always a pain. Therefore, if you need Cartesian coordinates at the end, convert the coordinates to Cartesian first. Then you can easily translate them into any coordinate system by simply multiplying by the correct matrix.

pld
Posts: 2
Joined: Mon Nov 30, 2020 4:32 pm

Re: How to get Sector and Vector Coords of star?

Post by pld » Sat Dec 05, 2020 7:09 pm

I have an additional question today.
how is the vector of a ship from hyperspace calculated when entering a star system? ...

pld
Posts: 2
Joined: Mon Nov 30, 2020 4:32 pm

Re: How to get Sector and Vector Coords of star?

Post by pld » Sat Dec 05, 2020 7:19 pm

...and so, I mean it's flat space
(coordinate stars)
the solution is a random vector of the ship and.
ecliptic planes must be randomly generated or specified in a file, etc.

It is obvious

Post Reply

Who is online

Users browsing this forum: No registered users and 2 guests