![]() ![]() (see for more information).Ĭonversion from Galactic XYZ to Astrosynthesis XYZ Galactic latitude is also measured from Sol, with positive (Galactic North) latitudes being above the galactic plane, and negative (South) latitudes being below the galactic plane. Since Sol is actually located about 67 lightyears above galactic plane, the Galactic Equator is the plane parallel to the galactic plane with Sol at its origin. Longitude is measured anticlockwise from this line (90° is Spinward, 180° is Rimward, 270° is Trailing). Instead, galactic co-ordinates are used – this co-ordinate system is centred on Sol, with 0° Galactic longitude pointing towards the galactic core (Coreward). Since these definitions are specific to Earth, it doesn’t make much sense to use them to mark star locations. Polaris is at a Declination of around +89°, making it the north pole star. ![]() A Dec of 0° would be at the celestial equator, defined as the projection of the earth’s equator into the celestial sphere. The RA zero meridian is the “first point of Aries”, where the sun crosses the celestial equator in March. RA (Right Ascension) is measured in hours/minutes/seconds, and Dec measured in degrees. Right Ascension and Declination are equatorial co-ordinates, and can be imagined as the Earth’s latitude and longitude projected into the celestial sphere. 1950.00) – this is due to inaccuracies in the older data, along with precession of the star co-ordinates since that epoch. The spreadsheets will not produce accurate results for data from earlier epochs (e.g. J2000.0 co-ordinates can be downloaded from Vizier using the “Compute” options in the search forms there. This conversion should also work without modification for J1991.25 equatorial co-ordinates from the Hipparcos database, but it’s best to use J2000.0 just in case. Note that J2000 equatorial co-ordinates must be entered into the spreadsheets. This spreadsheet will also convert to Astrosynthesis X, Y and Z co-ordinates.ĭownload: Bulk_Converter: converts lists of stars from J2000.0 equatorial to galactic co-ordinates A sample star is shown, and the Explanation tab explains the columns. If you want to convert lists of stars from equatorial to galactic co-ordinates and galactic XYZ, you can use the bulk_converter Excel 2007 spreadsheet – just copy/paste the RA/Dec or alpha/delta (decimal coordinates) and copy the formulae in the tables. (Thanks to Veeger, PraedSt, and Grant Hutchison from BAUTforum, and Spaceman Spiff and Selden from the Celestia forums for all their help with figuring out the conversions).ĭownload: Coordinate_converter: J2000.0 equatorial co-ordinates galactic co-ordinates conversion spreadsheet The spreadsheet requires the Right Ascension and Declination (in hr/min/sec and deg/min/sec respectively, both in J2000.00 epoch) and the J2000.00 trigonometric parallax values (in arcseconds). All of these data can be accessed from Vizier and other sources. The Excel 2007 coordinate_converter spreadsheet allows you to convert between J2000.0 Right Ascension/Declination and Galactic Latitude/Longitude (both ways) for a single star, and also provides X/Y/Z co-ordinates for the star if its parallax is known. stars added to datasets that had been omitted for various reasons). Section 5 lists any updates to the data presented on this page. Section 4 presents links to additional articles that expand on the Stellar Mapping page! Section 3 provides some advice and ideas for combining and presenting the data in Astrosynthesis. AstroDB files are not included here since they can be easily generated using Astrosynthesis after importing this data. ![]() The data is presented in CSV (comma separated variable) format, which can be read into both Excel and Astrosynthesis. Several star datasets and catalogues are provided (each with its own advantages and disadvantages) that include stars up to 300 lightyears from Sol. An Excel file is also provided for users to convert from RA/DEC to Galactic Coordinates and back again. Section 1 describes the techniques used to convert existing astronomical data into a more usable form. The stellar data is visualised using Astrosynthesis 3.0, published by NBOS, which is available for $35 from DrivethruRPG and RPGNow (I strongly recommend buying it if you’re interested in this sort of thing – which presumably you are, since you’re reading this – it’s an excellent 3D visualisation tool!) Every effort has been made to make the data as simple to interpret as possible, though FTL routes have not been calculated here. This dataset is aimed at anyone interested in astronomy or who is interested in adding nearby stars to their own RPG or sci-fi/Traveller universes – the raw data is easily adaptable to any sci-fi setting or RPG. The aim of this project is to show the locations of the stars around Sol as accurately as possible.
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