The HYG Database, constructed by David Nash, combines the Hipparcos, Yale Bright Star and Gliese catalogues. It contains explicit xyz-coordinates for each of its 119,614 stars. Our hyg119614 instance of the TSP contains the full collection. But a word of warning. 10,215 of the HYG points are placed on a sphere exactly 100,000 parsecs from Earth, whereas each of the remaining 109,399 stars has distance less than 1,000 parsecs.
You can see the unusual structure in the image at the top of the page. The white dot in the middle is home to 109,399 stars. The two long diagonal lines indicate the legs of the tour from these core stars to the 100,000-parsec outer rim and back again. For a tour of just the core stars, see the hyg109399 page.
The data for hyg119614 were extracted from Field 13 in the original hygdata_v3.csv.gz file. The HYG Database provides the following description.
We scaled the coordinates by 10 to put them in units of 1/10th parsecs. The resulting 119,614 xyz triples of coordinates are listed in each of the following two files, one star per per line.
• hyg119614.xyz, list of coordinates
• hyg119614.tsp, the coordinates in TSPLIB format.
To order of the points in hyg119614 matches the order of the entries in the hygdata_v3.csv file on the HYG Database page.
The following three files give our optimal tour.
• hyg119614_order.txt, the points for hyg119614 permuted in optimal order,
• hyg119614_tour.txt, a list of integers from 1 up to 119,614, giving the order the stars appear in the tour,
• hyg119614.tour, the tour in TSPLIB format.
To create an instance of the TSP, we need to specify precisely the point-to-point distances we use. For this we adopt the standard TSPLIB norm for 3D Euclidean data. This norm takes the straight-line distance between two points and rounds the resulting value to the nearest integer. In our case, the star-to-star distance is therefore measured to the nearest 1/10th parsec. Here is a simplified version of the computer code used in Concorde for the distance calculation.
Stars -- Zoom, pan, and rotate the data set to see its 3D structure. Stars are represented by twinkling points.
Light -- In this version, stars are represented as square particles, resulting in an image that is easier to render (in case you have trouble with the twinkling version).
