P200 Primary Mirror Backsupport Status


Update 27 Feb

We are happy to report that we were back on the sky for testing with
P200 this week.  As the weather would allow, the telescope delivered
excellent image quality (e.g. ~ 1" early Tuesday and Thursday nights),
and no signs of the mechanical hysteresis that the refurbishment aimed
to correct.  The team took a large amount of image and extra-focal
data (so as to assess the primary mirror figure), and will be working
through that data in the coming days.

At this point we will go forward with the announced schedule of
contingency observers, and are optimistic that the mirror will
continue to perform well.  Congratulations and thanks to Jeff
Zolkower, Hal Petrie, Keith Matthews, Dan McKenna, and the entire
observatory staff for their outstanding planning and execution of the
P200 Mirror Backsupport refurbishment.





Update 21 Feb:


As of Friday 19 February all 36 mirror supports have been removed,
refurbished, and re-installed into the telescope.  On Friday morning we
started the process of mechanical adjustment of the supports for
axial, azimuthal, and lateral position.  We should be finished with
these adjustments on Monday morning.  Over the weekend we are bringing
the mirror back down to the nighttime ambient temperature in
preparation for on-sky testing.  Depending of the weather forecast for
Monday night, we will prepare the telescope for observing and optical
testing, or if on-sky tests are unlikely, keep it in a mechanical
testing mode with the Cass cage removed.  A series of mechanical tests
have been planned in case the weather does not cooperate.


Our first contingency observers are scheduled for Sunday 28 February;
pending the outcome of image quality tests this week we believe it is
highly likely that the telescope will be ready for a return to science
operations to support contingency observations.








Update 13 Feb:

As of Friday afternoon (12 Feb), 31 of the 36 mirror backsupport
assemblies have been removed, refurbished, and re-installed in the
telescope, with an additional two refurbished assemblies waiting for
re-installation.  Only one unrefurbished unit needs to be removed from
the telescope.  We estimate that the refurbishment work will be
finished by Wednesday afternoon (in the holiday-shortened week).
After the last unit is installed, we will begin the process of support
system adjustment, involving axial, azimuthal, and lateral tuning of
each support relative to the mirror and each other.  We estimate this
process will take two days.  During this adjustment period, we will
turn off the heaters, and begin to cool the dome, telescope structure
and mirror.  Our present schedule is to begin on-sky testing, tuning,
& verification on 22 Feb.





Update 5 Feb:

At present (5 Feb) 17 (of 36) mirror supports have been removed,
refurbished, and replaced (two more are presently out of the telescope
and being refurbished).  To date the refurb crew has averaged processing
roughly 2 supports/day.  This (17/36, 2/day) is actually slightly
ahead of our projected status +and+ rate for this point on the
refurb activity, and all signs indicate that we will complete the refurb
on or slightly ahead of schedule.  The crew is performing extremely
well, and is taking a well-deserved weekend off to watch the SuperBowl!




---

Last Updated: 27 February 2010  AFB