It is a chart of the stars on a given night from a given location on earth. These charts are the electronic version of what is known as Planispheres in Astronomy. A Planisphere is a star chart analog computing instrument in the form of two adjustable disks that rotate on a common pivot. It can be adjusted to display the visible stars for any time and date. It is an instrument to assist in learning how to recognize stars and constellations.
Our maps are plotted out of thousands of stars, showing you what is visible on a particular night from a specific location on a night you choose. Along with the stars, our software plots the most known constellations and the outline of our galaxy, The Milkyway. All map elements are plotted with the highest known scientific accuracy. We use Yale’s Bright Star Catalog and other astronomical databases for our celestial data which contain the coordinates and brightness of each known star in the galactic coordinate system. For constellation lines, we use Donald Menzel’s A Field Guide to the Stars and Planets. We also include Deep Sky Objects (e.g. nebulas and galaxies) and their labels which are available in the Messier Catalog and the New General Catalog.
Each customized map is generated after processing thousands of stars and hundreds of related data points to the greatest scientific accuracy. You can compare our maps with ones generated by open source software packages, such as Stellarium.