Mt. Hopkins: March 25, 1999
Early on the morning of March 25, 1999, the primary mirror was ready
for installation. Preparations of the previous day included the
assembly of the lifting fixture and vacuum tests of the suction pads
and associated pumps. The lift had been planned for the afternoon of the
25th, but impending inclement weather forced a re-scheduling to the early
morning to beat the incoming storm.
The joint MMTO/Steward Observatory crew assembled at about 6:00 AM for
a pre-lift briefing by JT Williams, who directed the lift. At 7:10
a.m., a 120-ton crane from Marco Crane & Rigging began to hoist the
lifting spider holding the $10 million primary over the top of the
building and lower it into the optics support structure.
By 8:40 a.m., observatory staffs were aligning the mirror very carefully to
its cell, to within an accuracy of a couple of millimeters At 10:26 a.m.,
the mirror cell supported the entire 10-ton weight of the glass, with the
crane holding only the 7-ton lifting fixture. Williams announced that the
mirror was wholly free of crane support and cradled only by the cell.
A half-hour later, celebratory root beer was popped and passed around
among staff. They still had a long day ahead, clearing the small,
crowded summit of vehicles and equipment. But we'll never face this
task again -- the mirror has been installed for the life of the
telescope. The MMT currently has the biggest single-piece primary
mirror on the North American continent.
Click here for pictures taken by Mark Wagner.
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