SLOOH.com is the world's first and only source of live deep-sky celestial images. Every night SLOOH's telescopes scan the skies and deliver stunning images to computer screens around the world in seconds. SLOOH offers a schedule of fascinating five- and 10-minute "missions" that probe galaxies, nebulas and comets. Any SLOOH subscriber can reserve time on a telescope and direct its actions. A user needs only a 56Kb modem connection to the Internet and a Web browser. No knowledge of astronomy is necessary. Empowering novices to remotely control a professional observatory is completely unprecedented in human history.

Let's steal a look behind the scenes to understand how SLOOH's technology conquers the skies. Its operations are housed at two locations. SLOOH built a unique robotic astronomical observatory in the Canary Islands and manages enterprise-class servers at a collocation site (a.k.a. colo) in New York City.

SLOOH's unmanned observatory is connected to the outside world only through the Internet. It operates autonomously, with occasional remote maintenance over the Internet. The SLOOH observatory hardware consists of two automated domes, each with a robotic mount, a wide field imaging system and a high magnification imaging system. Each imaging system has a telescope, a CCD astro-imaging camera, filters and a focuser. All functions of these systems are under software control running on personal computers.

SLOOH's key technological component is the custom control software running in the observatory. It is written in the Java programming language. This software:

• Handles communication with the servers
• Controls motorized actuation of the equipment
• Gathers data from instruments
• Performs image processing

The colo installation contains the systems that handle all user interaction, scheduling and administration. A SunFire V120 running Solaris 8 hosts an Apache 2 Web server and a MySQL 4 database. Verisign certificates are used for secure Web communications. The site makes extensive use of JSP and servlets. JRun integrates Java-based functionality and the Web site, the database and the observatory. A PC running Red Hat 8 hosts a Macromedia Flash Communication Server that powers the slick graphics of the Flash client plug-in.

Messages are sent between the colo and observatory using a custom RMI-based Remote Observatory Messaging Protocol. Every few minutes, the colo sends a command over the Internet to the observatory telling it to observe a particular celestial object. The observatory autonomously points the telescope, selects filters anf focuses and photographs the object. The images are sent from the observatory to the colo. Every action of the observatory is signaled with a message. For example, when the camera shutter opens, a message is sent. The images and messages are broadcast to each and every user's browser. The browser not only displays the image; it also displays telemetry showing almost every action at the observatory.

SLOOH was designed to convey the experience of being inside a working observatory. Pre-recorded voice audio germane to the objects is available to the user, providing a personalized "astro-tour guide."