During the ACS Repair (ACS-R) conducted during Hubble Servicing Mission
4 (SM4), astronauts will install a CCD Electronics Box Replacement
(CEB-R) and Low-Voltage Power Supply Replacement (LVPS-R). A rudimentary
aliveness/functional test (AT/FT) will be conducted on-orbit during SM4.
Shortly after SM4, the more comprehensive CCD function test (FT) defined
in this program will be conducted as part of SMOV. This program is
modeled after the original CCD functional test (HST program 9005, PI
Mark Clampin) conducted following the initial installation of ACS during
Hubble Servicing Mission 3B. This WFC-only proposal has a companion HRC
proposal 11396.

The goal of this program is to verify the amount of cross talk in the
ACS WFC detectors in the post SM4 era. Before the failure of ACS the
cross talk was very low at gain=1 e-/DN and almost not existent at
gain=2 e-/DN. We plan to verify if the cross talk with the new
electronics is still at levels that do not represent concerns for
science. Both gain=1 and gain=2 will be tested. A bright extended source
and several bright (likely saturated) stars will be used for the test.
The sources will be positioned in different quadrants to verify if any
specific amplifier is more affected to cross talks than others.

The program consists of four visits two orbits each. Only three visits
are supposed to be executed for a total of 6 orbits. The structure of
each visit is identical, the only difference is the correlated double
sapling technique.

Visit 01 and 02 should be executed program between programs 11814
(iteration #6 of the CEB-R optimization campaign) and program 11815
(iteration #7 of the CEB-R optimization campaign). The aim of these
visits is to confirm with external observations the impact of the new
electronics on the cross talk while we are still optimizing the CEB-R.

Visit 03 or visit 04 should be executed anytime after the end of the
CEB-R optimization campaign depending on which of the dual slope
integrator or correlated double sampling is adopted.

This program determines the fine focus using NUV MIRRORA exposures of
the same target as COS08 (program 11468 - COS to FGS Alignment (NUV)).
This program must commence execution approximately 48 hours after
completion of visit 1 of COS08 and as soon as possible after the uplink
in visit 2 of COS08. Three fine focus visits are executed to establish
on-orbit nominal focus. Two detailed verification visits are executed
after the three focus-sweep visits. Approximately 48 hours after each
odd-numbered visit an uplink of new information is required.

The UV throughput of WFC3 during SMOV is monitored via weekly standard
star observations in a subset of key filters (as many as will fit into a
single orbit but to include at a minimum F218W, F225W, F275W, and
F606W). The data will provide a measure of throughput levels as a
function of time and wavelength, allowing for detection of the presence
of possible contaminants. In addition, a small set of internal exposures
are included with the externals, to provide verification of detector
stability.

The corrector mechanism will be used to bring the UVIS channel of WFC3
into optimal alignment with the OTA using analysis of star images over
the field. Two visits are required; corrector offsets will be uplinked
after each visit via realtime command.

The UVIS detector was observed during ground testing to occasionally
exhibit flat field and dark variations with a bowtie pattern. These
variations are most significant as ~1% flat field (gain) variations
across the field of view. It is believed that this represents a state or
condition into which the detector can transition for reasons and under
circumstances which are not currently understood. It is also very
unlikely that most science observations will determine the state (bowtie
or no-bowtie) of the detector. Ground test data indicates that this
state is long lived (many hours to ~one day). Hysteresis or memory of
past light exposure is also associated with this state.

Recent evidence suggests that exposing the detector to ~200k to 500k
electrons may quench this state. This proposal obtains an internal flat
field sequence of three exposures: one at 10x full well with two at 0.5x
full well immediately before and after. Each exposure is 3x3 binned to
reduce the data volume required.

Significant Spacecraft Anomalies: (The following are preliminary reports
of potential non-nominal performance that will be investigated.)

COMPLETED OPS REQUEST:
18598-1 - Update COS Aperture and OSM Positions in FSW @ 189/1502z
18599-3 - Transition STIS from Suspend to Operate & Check MIE @ 190/0620z
18608-0 - Dump STIS Memory after Suspend on day 190 @ 190/0704z

                       SCHEDULED      SUCCESSFUL
FGS GSAcq               9                   9
FGS REAcq               8                    7
OBAD with Maneuver 7                  7

Flash Report:
During Ops Request 18599 to verify the functionality of the STIS MIE and
recover STIS to Operate mode, STIS Suspended at 190/06:19:48z due to a
STIS STB 100 "Invalid CS FSW Mode for more than 10 minor frames".