STScI Annual Report 2002: A Living Mission

Optimize Hubble science operations
A Hubble servicing mission always adds complexity and challenges for operating the observatory, and
SM3b, carried out in March of 2002, was no exception. The Institute did much preparatory work. We
took steps to accommodate the large increase in data volume we anticipated when ACS and NICMOS
became active. We defined the operations to commission the new hardware and re-commission the old.
We developed contingency plans for difficulties that might arise during the mission. This advanced
planning paid off, and we quickly returned Hubble to science observations after SM3b.
Institute staff members began supporting SM3b directly in the week prior to the shuttle launch,
while observations were still underway. Because of the potential for launch delays, we generated an
observing schedule that kept Hubble working whether or not the launch was on time. We achieved this by
scheduling Hubble to slew briefly, once a day, to the shuttle rendezvous attitude. If the shuttle launched,
we would stop observations at that point. If not, we would let Hubble slew to the next science target and
resume observations. (High winds at the launch pad did delay the launch one day.)
During the servicing mission, we monitored the instruments, analyzed ACS data to check performance,
and verified that the Space Telescope Imaging Spectrograph (STIS) showed no increase in electronic
noise. All went well. The shuttle astronauts released Hubble as planned on March 11, which started the
commissioning period, SMOV (Servicing Mission Orbital Verification).
Engineering and calibration measurements dominated the first two weeks of SMOV. The purpose
was to verify the performance of the observatory and the old instruments. We took care to ensure that
any outgassed organic material did not polymerize and contaminate the optics, which would degrade
ultraviolet performance. We resumed General Observer (GO) science observations with Wide Field
Planetary Camera 2 (WFPC2) and STIS on March 26. Then we began to interleave the commissioning
activities for the ACS and the NICMOS with its new cryocooler.
The cryocooler took weeks longer than expected to reach the planned operating temperature.
We moved up some ACS activities to compensate, initiating ACS science observations on April 8.
After its detectors were cold, we activated and tested the NICMOS itself, which had been dormant
for about 3 years.
After SMOV, we started executing the Cycle 11 program. Because the Telescope Allocation
Committee had selected many large programs (> 100 orbits), including three Hubble Treasury programs,
the pool of observations contained many more long and/or constrained observing programs than in the
past. We developed a year-long plan to accommodate
these observations, which began in earnest in August with
the first epoch of Great Observatories Origins Deep Survey
(GOODS) observations with ACS. At year’s end, large programs
dominated the Hubble schedule.
A particularly challenging aspect of GOODS is the need
for Target of Opportunity (ToO) follow-up observations
when a type Ia supernova is detected in the ACS images.
The GOODS observations are typically made at the end of a
week, and the ToO team provides decisions on the following
Monday or Tuesday, with any follow-up observations
SMOV3b
included in the following week’s schedule.
Maximum possible sustained observing efficiency is 58%
Figure 5 shows the scheduling efficiency in 2002 remained
high, averaging 49.4% after the completion of SMOV.
FIG 5: Weekly Scheduling Efficiency
70
60
50
40
30
20
10
0
Jan 01 Jun 01 Jan 02 Jun 02 Jan 03
scheduling week
Calibrate Hubble data
The Institute holds occasional Calibration Workshops for Hubble users, Institute staff, and instrument
developers to exchange information about instrument characterization, calibration, and performance. In
2002, we held the workshop on October 17 and 18 at the Institute. It featured reports on the commissioning
of ACS and the re-commissioning of NICMOS. It included approximately 30 invited talks, 40 posters,
demonstrations, and splinter meetings on various topics. About 120 astronomers attended. The workshop
proceedings will be published in 2003.
STScI AR 02 | A Living Mission
achievements
achievements 43