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Hubble Space Telescope
NICMOS STScI Analysis Newsletter 43

NICMOS STAN

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| NICMOS 
| STScI Analysis Newsletter 
| 21 September 2009 
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NICMOS Recovery: NCS cooldown - Instrument operational - SMOV proceeding


As of September 20, 2009, the recovery of NICMOS has passed a
significant milestone with the successful completion of the
filter wheel mechanism test, for all 3 cameras. This marks the
transition from the operational health and safety recovery
to the more nominal SMOV program that will now proceed.

The NCS crycooler system has been performing well since its
successful restart in August, when both the circulator and
the turboalternator were restarted at a set of thermal
conditions that were chosen to mitigate the risk of further
interference by ice contaminants in the system. The cooldown
proceeded smoothly to the nominal NCS setpoint of 72.4 K,
which it was able to maintain while the NICMOS instrument
remained in SAFE mode. After the NICMOS electronics were
enabled, which placed additional heat into the system, the
setpoint had to be raised to 75 K in order to allow a stable
temperature to be maintained.

The NICMOS detector electronics successfully passed their
initial check (the DC transfer test) on September 15, 2009
enabling the instrument to be transitioned to its operational
state. With the subsequent verification of the focus mechanisms
and filter wheel operation, NICMOS is now able to continue
with the rest of the nominal SMOV programs through October.
Some further tests will be carried out to determine the best
temperature setpoint for the final stable operational state
of the instrument. Given the new thermal configuration post-SM4,
NICMOS will likely be operated a few degrees warmer than pre-SM4;
initial indications are that this can be calibrated as before.

For subsequent information about the instrument characteristics
and progress of the SMOV program, please consult the NICMOS
webpages:  http://www.stsci.edu/hst/nicmos


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