Naked eye sky v19.6.29 Move the chart by dragging with mouse or 1-finger touch

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This program was first written in Java around 2011 when I was developing a talk to give to photographers to try to interest them in doing astrophotography. There are about 5,000 stars visible to the naked eye in an unpolluted night sky. The data for these stars come from the Hipparcos mission of the European Space Agency (ESA) in the 1990s. The data are freely available on a web site of the University of Strasbourg. I have processed the data to extract just those stars brighter than magnitude 6.5.

I am amazed that this JavaScript version of the program runs as fast as it does in current browsers. Not only are there 5,000 stars whose positions within the chart have to be calculated but there are lists of constellation names and connecting lines. Also every star is drawn with a Gaussian profile calculated specifically for that star. All of that has to be recalculated every time the chart is drawn. That means every time it is dragged with the mouse or finger, yet dragging by mouse works in real time (finger dragging is slower because I convert touch events to mouse events and that seems to take some time).