Visitors can explore the skies and roam the University of Pittsburgh's historic Allegheny Observatory during a free open house from 7 to 10 p.m. Oct. 1, but reservations are required. Tickets are available beginning at 9 a.m. Monday.

The reservations are limited to six people per group and can be made by calling the observatory at 412-321-2400 between 9 a.m. and 5 p.m.

During the open house, visitors can look at the night sky through the 30-inch Thaw refractor telescope, a 47-foot telescope normally reserved for research. Members of the Amateur Astronomers Association of Pittsburgh also will set up telescopes on the lawn for the public, and if the night is clear, guests can see a close-up of Jupiter through the 13-inch, 149-year-old Fitz-Clark refractor telescope.

The observatory is located at 159 Riverview Ave., Riverview Park.

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