Daily # 4136

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4136

PERIOD COVERED: UT June 15, 2006 (DOY 166)

OBSERVATIONS SCHEDULED

ACS/HRC 10571

The Compact Disk of Blue Stars Orbiting the M31 Black Hole

We propose ACS/HRC U and B band imaging of the compact cluster of blue
stars at the precise center of M31, which hosts the 1.3X10^8
solar-mass nuclear black hole. Analysis of STIS spectra and WFPC2
images suggest that the cluster is actually a disk. Recovering an
accurate light distribution of the disk is essential for obtaining a
precise estimate of the black hole mass from the STIS spectra, an
approach that is attractive as it bypasses modeling the complex
structure and dynamics of the M31 double nucleus by using the
Keplerian rotation of the blue disk as a direct mass indicator.
Dithered ACS/HRC observations in the blue provide the best spatial
resolution available from HST, which is ~2X finer than could be
obtained by the WFPC2 observations that first elucidated the structure
of the blue cluster. The cluster effective radius {barely resolved by
WFPC2} is only ~ 0.06'', thus the ultimate resolution and improved S/N
offered by re-observation with ACS/HRC are essential to fully
understand the disk inclination and radial starlight distribution.
Analysis of the "smoothness" of the blue light distribution may also
reveal its composition. The low-luminosity of the disk, M{AB}=-5.5 can
be produced by only a few hundred A-stars, a small enough number that
fluctuation statistics should leave an obvious signature on the light
distribution.

ACS/HRC/WFC 10733

CCD Hot Pixel Annealing

Hot pixel annealing will continue to be performed once every 4 weeks.
The CCD TECs will be turned off and heaters will be activated to bring
the detector temperatures to about +20C. This state will be held for
approximately 6 hours, after which the heaters are turned off, the
TECs turned on, and the CCDs returned to normal operating condition.
To assess the effectiveness of the annealing, a bias and four dark
images will be taken before and after the annealing procedure for both
WFC and HRC. The HRC darks are taken in parallel with the WFC darks.
The charge transfer efficiency {CTE} of the ACS CCD detectors declines
as damage due to on-orbit radiation exposure accumulates. This
degradation has been closely monitored at regular intervals, because
it is likely to determine the useful lifetime of the CCDs. We combine
the annealling activity with the charge transfer efficiency monitoring
and also merge into the routine dark image collection. To this end,
the CTE monitoring exposures have been moved into this proposal . All
the data for this program is acquired using internal targets {lamps}
only, so all of the exposures should be taken during Earth occultation
time {but not during SAA passages}. This program emulates the ACS
pre-flight ground calibration and post-launch SMOV testing {program
8948}, so that results from each epoch can be directly compared.
Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}
data will be obtained over a range of signal levels for both the Wide
Field Channel {WFC}, and the High Resolution Channel {HRC}.

FGS 10612

Binary Stars in Cyg OB2: Relics of Massive Star Formation in a
Super-Star Cluster

We propose to make a high angular resolution SNAP survey of the
massive stars in the nearby, super-star cluster Cyg OB2. We will use
FGS1r TRANS mode observations to search for astrometric companions in
the separation range of 0.01 to 1.00 arcsec and in the magnitude
difference range smaller than 4 magnitudes. The observations will test
the idea that the formation of very massive stars involves mergers and
the presence of nearby companions. Discovery of companions to massive
stars in this relatively nearby complex will provide guidance in the
interpretation of apparently supermassive stars in distant locations.
The search for companions will also be important for verification of
fundamental parameters derived from spectroscopy, adjustments to main
sequence fitting and distance estimations, determining third light
contributions of eclipsing binaries, identifying wide colliding wind
binaries, studying the relationship between orbital and spin angular
momentum, and discovering binaries amenable to future mass
determinations. The massive star environment in Cyg OB2 may be similar
to the kinds found in the earliest epoch of star formation, so that a
study of the role of binaries in Cyg OB2 will help us understand the
formation processes of the first stars in the Universe.

NIC1/NIC2 10410

Anisotropy and obscuration in the near-nuclear regions of powerful
radio galaxies

Despite the success of the orientation-based unified schemes for
powerful radio sources, we are still far from understanding the
distribution of obscuring material in the near-nuclear regions of such
sources, and how this distribution evolves with radio power. Following
on from our highly successful Cycle 7 pilot observations of Cygnus A,
we propose a near-IR polarimetric survey of a complete sample of
powerful radio galaxies in order map the near-nuclear illumination
cones, and investigate the distribution of obscuring material on a 0.1
to 1kpc scale. In particular, the observations will allow us to test
the "receding torus model'' which predicts that the opening angles of
the illumination cones are smaller in low redshift/low power radio
galaxies than in their high redshift/high power counterparts.We will
also investigate whether AGN- and jet-driven outflows have a
substantial effect on distribution of obscuring material by "hollowing
out'' the quasar illumination cones in the more powerful sources.
Finally, by using our polarization maps to search for signs of
intrinsic anisotropy in the near-IR continuum within the cones, we
will investigate the geometry of the near-IR continuum emitting
regions close to the quasar nuclei. These observations are not only
crucial for our understanding of radio source unification, but also
provide key information about the effects of AGN-induced outflows on
the ISM of the host galaxies.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

A new procedure proposed to alleviate the CR-persistence problem of
NICMOS. Dark frames will be obtained immediately upon exiting the SAA
contour 23, and every time a NICMOS exposure is scheduled within 50
minutes of coming out of the SAA. The darks will be obtained in
parallel in all three NICMOS Cameras. The POST-SAA darks will be
non-standard reference files available to users with a USEAFTER
date/time mark. The keyword 'USEAFTER=date/time' will also be added to
the header of each POST-SAA DARK frame. The keyword must be populated
with the time, in addition to the date, because HST crosses the SAA ~8
times per day so each POST-SAA DARK will need to have the appropriate
time specified, for users to identify the ones they need. Both the raw
and processed images will be archived as POST-SAA DARKSs. Generally we
expect that all NICMOS science/calibration observations started within
50 minutes of leaving an SAA will need such maps to remove the CR
persistence from the science images. Each observation will need its
own CRMAP, as different SAA passages leave different imprints on the
NICMOS detectors.

S/C/NIC1 10724

NICMOS Focus Monitoring

The purpose of this proposal is to determine the best focus for all
three NICMOS detectors. The program will be executed every ~6 weeks.
Each execution will concern a single detector, except two occasions
which will include NIC3. In total NIC1 and NIC2 will be monitored 4
times each during the current cycle, while NIC3 will only be monitored
twice. The program starts with a focus sweep using only the NIC1
camera {visit 11}. The following observation is with the NIC2 camera
{visit 12} after about 45 days. This pattern is repeated throughout
the period except for Jan 1-8 and Jul 1-8 where also the NIC3 camera
is used. In total this will result in 10 orbits. Notice that VISIT #1
#2 refers to visits for #1 sequential visit number for a given camera
#2 camera in question visit 32 is therefore the third visit for camera
2. Some tweaking of dates and sources are necessary to ensure
visibility under 2-gyro mode. These are the dates and targets for
Cycel14: Visit 11: Oct 01-08 NIC1 NGC1850 Visit 12: Nov 15-22 NIC2
NGC3603 Visit 21: Jan 01-15 NIC1 NGC3603 Visit 13: Jan 01-15 NIC3
NGC3603 Visit 22: Feb 15-22 NIC2 NGC3603 Visit 31: Apr 01-15 NIC1
NGC1850 Visit 32: May 22-31 NIC2 NGC3603 Visit 41: Jun 15-22 NIC1
NGC1850 Visit 23: Jun 15-22 NIC3 NGC1850 Visit 42: Aug 07-22 NIC2
NGC3603

WFPC2 10534

Active Atmospheres on Uranus and Neptune

We propose Snapshot observations of Uranus and Neptune to monitor
changes in their atmospheres on time scales of weeks, months, and
years. Uranus is rapidly approaching equinox in 2007, with another 4
degrees of latitude becoming visible every year. Recent HST
observations during this epoch {including 6818: Hammel, Lockwood, and
Rages; 8680: Hammel, Rages, Lockwood, and Marley; 8634: Rages, Hammel,
Lockwood, Marley, and McKay; and 10170: Rages, Hammel, Lockwood, and
Marley} have revealed strongly wavelength-dependent latitudinal
structure and the presence of numerous visible-wavelength cloud
features in the northern hemisphere. Long-term ground-based
observations {Lockwood and Thompson 1999} show seasonal brightness
changes whose origins are not well understood. Recent near-IR images
of Neptune obtained using adaptive optics on the Keck Telesccope
together with images from our Cycle 9 Snapshot program {8634} show a
general increase in activity at south temperate latitudes as well as
the possible development of another Great Dark Spot. Further Snapshot
observations of these two dynamic planets will elucidate the nature of
long-term changes in their zonal atmospheric bands and clarify the
processes of formation, evolution, and dissipation of discrete albedo
features.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10316 ACS Semaphore timeout @166/1931z

NSSC-I status buffer message ACS 935, P=35, "Semaphore timeout" was
received at 19:31:10. This is a routine status buffer message
indicating a Semaphore_Timeout, which results when the Take Data Flag
goes down during CCD Post-Flash or a Filter wheel, Fold Mechanism, or
Calibration door move.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 08 08
FGS REacq 06 06
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS:

HST Safemode Recovery Status:

At 166/11:42, the first Guide Star acquisition of the Science
intercept SMS was successful, and activity on the intercept SMS
continues nominally.