A number of caveats are provided on the use of ISSA images, which can contain traps for the unwary. Web clients dial into AstroVR, where a general purpose Web Server handles the request by dispatching it to the postage stamp generating object. There, the target string is taken and recast into the query grammar of the low-level postage stamp server running at IPAC, which requires a valid position. If successful, this query returns a position and the low-level server is tried again. We chose this size because it is the largest size that guarantees that the entire field will be on a single plate, and our philosophy is not to do any further processing of the data, such as creating mosaics, which might alter its reliability and usefulness.
Users are, of course, free to do so at their end.
Once extracted and saved to a public ftp area, gif representations of the postage stamps are made, and pointers to all these files are returned to the managing server. There an html page is generated, containing the gifs as inline images, along with text containing the target coordinates and a number of caveats as to the use of ISSA images. The html page is sent back to the user and formatted by their Web client. The service gets from a few to 50 requests a day, averaging about 10. We log connecting site names, and find that there are many casual users as well as obviously astronomical users.