A vertical solar telescope feeds a white-light image of the Sun into the undergraduate astronomy laboratory. The coelestat mirror system shown here tracks the daily motion of the Sun and directs light downward into the telescope supported from the ceiling of the astronomy lab. ... Conditions in the ionosphere responsible for the strength of the signal are very sensitive to X-ray flux from solar flares and sudden x-ray emitting events outside the solar system, and rapidly alter the received signal. ...

A brief introduction to the XPA messaging system, which provides seamless communication between all kinds of Unix event-driven programs, including X programs, Tcl/Tk programs, and Perl programs. ... A program becomes an XPA-enabled server by defining named points of public access through which data and commands can be exchanged with other client programs (and users). ... An XPA name server program, xpans, through which XPA access point names are registered by servers and distributed to clients. ...