by: John M. Hill
The official "opening ceremony" is scheduled for Friday September 12.
We look forward to seeing a lovely 8.4m honeycomb with a faceplate
that goes the WHOLE WAY ACROSS.
Thanks to the oven pilot crew (Randy, Dan, Phil, Ned, Rex, Carl and
Bruce) for their vigil to keep the furnace running smoothly for the past 4
months.
Summary:
The LBT 8.4m mirror has cooled to a temperature of 55 ° C and
we have turned off the heater power to the furnace.Report:
At 16:50 this afternoon, the furnace had reached a
sufficiently
low level of power input (an average of 40 Watts) that we deemed it
time to turn off the electrical power and send the watchful oven
pilots home. We are all extremely pleased that we have safely annealed and
cooled the 8.4m mirror through monsoon season without loss of power
or control. Especially we are glad because a really big storm is brewing
on the west side of Tucson. The temperature of the furnace has cooled
to 56 °C while the inside of the honeycomb mold is 60
°C. There is at least another week of "free-fall" cooling before the
glass gets close enough to room temperature for us to remove the lid
of the furnace. The cooling rate will continue to tail off as we
asymptotically approach ambient temperature. We can't safely peek
until the inside of the mold is within 8 degrees C of ambient
temperature. Of course, ambient in Tucson at the end of August is
fairly high. The cooling process is now extremely safe as the
furnace no longer requires either power or computer control. If we can avoid
any direct asteroid impacts, we should be home free.
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