Good suggestions! Works perfectly now. Thank you for your help. I had to convert JScript to VBS (even EquDist() was JScript) and build (er, steal) an ArcCosine function.

In another message I'll post this ACP Add-on that draws a 30' x 30' map of the sky where the telescope is pointing, using the reference catalog set up in ACP/Preferences for the stars. The Add-on has an .asp file that goes in the .../ac folder, and two new tiddlers - one to call the .asp file and also a "slider" for a brief information pop-up.

Thanks again.