[amsat-bb] Planetarium program?

Hi,

Any recommendations of a good freeware planetarium program, or web site, where you can put in the parameters of an object such as a comet and your QTH, and get the azimuth and elevation? Somewhat off topic, but someone who saw my antennas asked. Google of course is very productive, probably too much so.

73s,

Alan WA4SCA