Daily Report # 4429

Notice: Due to the conversion of some ACS WFC or HRC observations into
WFPC2, or NICMOS observations after the loss of ACS CCD science
capability in January, there may be an occasional discrepancy between
a proposal's listed (and correct) instrument usage and the abstract
that follows it.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** # 4429

PERIOD COVERED: UT August 17,18,19, 2007 (DOY 229,230,231)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

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 DARKs. 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.

WFPC2 11312

The Local Cluster Substructure Survey {LoCuSS}: Deep Strong Lensing
Observations with WFPC2

LoCuSS is a systematic and detailed investigation of the mass,
substructure, and thermodynamics of 100 X-ray luminous galaxy clusters
at 0.15z0.3. The primary goal is to test our recent suggestion that
this population is dominated by dynamically immature disturbed
clusters, and that the observed mass-temperature relation suffers
strong structural segregation. If confirmed, this would represent a
paradigm shift in our observational understanding of clusters, that
were hitherto believed to be dominated by mature, undisturbed systems.
We propose to complete our successful Cycle 15 program {SNAP:10881}
which prior to premature termination had delivered robust weak-lensing
detections in 17 clusters, and candidate strongly-lensed arcs in 11 of
these 17. These strong and weak lensing signals will give an accurate
measure of the total mass and structure of the dark matter
distribution that we will subsequently compare with X-ray and Sunyaev
Zeldovich Effect observables. The broader applications of our project
include 1} the calibration of mass-temperature and mass-SZE scaling
relations which will be critical for the calibration of proposed dark
energy experiments, and 2} the low redshift baseline study of the
demographics of massive clusters to aid interpretation of future high
redshift {z1} cluster samples. To complete the all-important high
resolution imaging component of our survey, we request deep WFPC2
observations of 20 clusters through the F606W filter, for which
wide-field weak-lensing data are already available from our Subaru
imaging program. The combination of deep WFPC2 and Subaru data for
these 20 clusters will enable us to achieve the science program
approved by the Cycle 15 TAC.

NIC2 11219

Active Galactic Nuclei in nearby galaxies: a new view of the origin of
the radio-loud radio- quiet dichotomy?

Using archival HST and Chandra observations of 34 nearby early-type
galaxies {drawn from a complete radio selected sample} we have found
evidence that the radio-loud/radio-quiet dichotomy is directly
connected to the structure of the inner regions of their host galaxies
in the following sense: [1] Radio-loud AGN are associated with
galaxies with shallow cores in their light profiles [2] Radio-quiet
AGN are only hosted by galaxies with steep cusps. Since the brightness
profile is determined by the galaxy's evolution, through its merger
history, our results suggest that the same process sets the AGN
flavour. This provides us with a novel tool to explore the
co-evolution of galaxies and supermassive black holes, and it opens a
new path to understand the origin of the radio-loud/radio-quiet AGN
dichotomy. Currently our analysis is statistically incomplete as the
brightness profile is not available for 82 of the 116 targets. Most
galaxies were not observed with HST, while in some cases the study is
obstructed by the presence of dust features. We here propose to
perform an infrared NICMOS snapshot survey of these 82 galaxies. This
will enable us to i} test the reality of the dichotomic behaviour in a
substantially larger sample; ii} extend the comparison between
radio-loud and radio-quiet AGN to a larger range of luminosities.

FGS 11212

Filling the Period Gap for Massive Binaries

The current census of binaries among the massive O-type stars is
seriously incomplete for systems in the period range from years to
millennia because the radial velocity variations are too small and the
angular separations too close for easy detection. Here we propose to
discover binaries in this observational gap through a Faint Guidance
Sensor SNAP survey of relatively bright targets listed in the Galactic
O Star Catalog. Our primary goal is to determine the binary frequency
among those in the cluster/association, field, and runaway groups. The
results will help us assess the role of binaries in massive star
formation and in the processes that lead to the ejection of massive
stars from their natal clusters. The program will also lead to the
identification of new, close binaries that will be targets of long
term spectroscopic and high angular resolution observations to
determine their masses and distances. The results will also be
important for the interpretation of the spectra of suspected and newly
identified binary and multiple systems.

WFPC2 11203

A Search for Circumstellar Disks and Planetary-Mass Companions around
Brown Dwarfs in Taurus

During a 1-orbit program in Cycle 14, we used WFPC2 to obtain the
first direct image of a circumstellar disk around a brown dwarf. These
data have provided fundamental new constraints on the formation
process of brown dwarfs and the properties of their disks. To search
for additional direct detections of disks around brown dwarfs and to
search for planetary-mass companions to these objects, we propose a
WFPC2 survey of 32 brown dwarfs in the Taurus star-forming region.

WFPC2 11179

Dynamics of Clumpy Supersonic Flows in Stellar Jets and in the
Laboratory

We propose to reobserve three stellar jets in order to quantify how
rapidly clumps in these flows accelerate and decelerate, and to
compare the results with ongoing numerical simulations and laboratory
experiments. Each jet has been imaged twice before with HST, and
precise proper motions have been measured for all emitting knots in
the jets. Images from the first two epochs show clear differential
motions between adjacent clumps, as well as shear, and possibly
fragmentation. The proposed third epoch will enable us to measure the
first ever accelerations in jets, quantify errors in existing proper
motion measurements, and observe in real time how fluid instabilities
develop in supersonic flows. The new images will make it possible to
compare the behavior of astrophysical flows directly with numerical
simulations and with laboratory experiments of bow shocks and clumpy
flows in progress at the Omega laser facility.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of
Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens
a window into dynamical conditions in the protoplanetary disk where
they formed as well as the history of subsequent events which sculpted
the outer Solar System and emplaced them onto their present day
heliocentric orbits. To date, at least 47 TNBs have been discovered,
but only about a dozen have had their mutual orbits and separate
colors determined, frustrating their use to investigate numerous
important scientific questions. The current shortage of data
especially cripples scientific investigations requiring statistical
comparisons among the ensemble characteristics. We propose to obtain
sufficient astrometry and photometry of 23 TNBs to compute their
mutual orbits and system masses and to determine separate primary and
secondary colors, roughly tripling the sample for which this
information is known, as well as extending it to include systems of
two near-equal size bodies. To make the most efficient possible use of
HST, we will use a Monte Carlo technique to optimally schedule our
observations.

ACS/SBC WFPC2 11175

UV Imaging to Determine the Location of Residual Star Formation in
Galaxies Recently Arrived on the Red Sequence

We have identified a sample of low-redshift {z = 0.04 - 0.10} galaxies
that are candidates for recent arrival on the red sequence. They have
red optical colors indicative of old stellar populations, but blue
UV-optical colors that could indicate the presence of a small quantity
of continuing or very recent star formation. However, their spectra
lack the emission lines that characterize star-forming galaxies. We
propose to use ACS/SBC to obtain high- resolution imaging of the UV
flux in these galaxies, in order to determine the spatial distribution
of the last episode of star formation. WFPC2 imaging will provide B,
V, and I photometry to measure the main stellar light distribution of
the galaxy for comparison with the UV imaging, as well as to measure
color gradients and the distribution of interstellar dust. This
detailed morphological information will allow us to investigate the
hypothesis that these galaxies have recently stopped forming stars and
to compare the observed distribution of the last star formation with
predictions for several different mechanisms that may quench star
formation in galaxies.

WFPC2 11156

Monitoring 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 and months.
Uranus equinox is only months away, in December 2007. Hubble Space
Telescope observations during the past several years {Hammel et al.
2005, Icarus 175, 284 and references therein} have revealed strongly
wavelength-dependent latitudinal structure, the presence of numerous
visible-wavelength cloud features in the northern hemisphere, at least
one very long-lived discrete cloud in the southern hemisphere, and in
2006 the first dark spot ever seen on Uranus. Long-term ground-based
observations {Lockwood and Jerzekiewicz, 2006, Icarus 180, 442; Hammel
and Lockwood 2007, Icarus 186, 291} reveal seasonal brightness changes
whose origins are not well understood. Recent near-IR images of
Neptune obtained using adaptive optics on the Keck Telescope, together
with HST observations {Sromovsky et al. 2003, Icarus 163, 256 and
references therein} which include previous Snapshot programs {GO 8634,
10170, 10534} show a general increase in activity at south temperate
latitudes until 2004, when Neptune returned to a rather Voyager-like
appearance. 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.

WFPC2 11030

WFPC2 WF4 Temperature Reduction #3

In the fall of 2005, a serious anomaly was found in images from the
WF4 CCD in WFPC2. The WF4 CCD bias level appeared to have become
unstable, resulting in sporadic images with either low or zero bias
level. The severity and frequency of the problem was rapidly
increasing, making it possible that WF4 would soon become unusable if
no work-around were found. Examination of bias levels during periods
with frequent WFPC2 images showed low and zero bias episodes every 4
to 6 hours. This periodicity is driven by cycling of the WFPC2
Replacement Heater, with the bias anomalies occurring at the
temperature peaks. The other three CCDs {PC1, WF2, and WF3} appear to
be unaffected and continue to operate properly. Lowering the
Replacement Heater temperature set points by a few degrees C
effectively eliminates the WF4 anomaly. On 9 January 2006, the upper
set point of the WFPC2 Replacement Heater was reduced from 14.9C to
12.2C. On 20 February 2006, the upper set point was reduced from 12.2C
to 11.3C, and the lower set point was reduced from 10.9C to 10.0C.
These changes restored the WF4 CCD bias level; however, the bias level
has begun to trend downwards again, mimicking its behavior in late
2004 and early 2005. A third temperature reduction is planned for
March 2007. We will reduce the upper set point of the heater from
11.3C to 10.4C and the lower set point from 10.0C to 9.1C. The
observations described in this proposal will test the performance of
WFPC2 before and after this temperature reduction. Additional
temperature reductions may be needed in the future, depending on the
performance of WF4. Orbits: internal 26, external 1.

ACS/SBC 10872

Lyman Continuum Emission in Galaxies at z=1.2

Lyman continuum photons produced in massive starbursts may have played
a dominant role in the reionization of the Universe. Starbursts are
important contributors to the ionizing metagalactic background at
lower redshifts as well. However, their contribution to the background
depends upon the fraction of ionizing radiation that escapes from the
intrinsic opacity of galaxies below the Lyman limit. Current surveys
suggest escape fractions of a few percent, up to 10%, with very few
detections {as opposed to upper limits} having been reported. No
detections have been reported in the epochs between z=0.1 and z=2. We
propose to measure the fraction of escaping Lyman continuum radiation
from 15 luminous z~1.2 galaxies in the GOODS fields. Using the
tremendous sensitivity of the ACS Solar- blind Channel, we will reach
AB=30 mag., allowing us to detect an escape fraction of 1%. We will
correlate the amount of escaping radiation with the photometric and
morphological properties of the galaxies. A non-detection in all
sources would imply that QSOs provide the overwhelming majority of
ionizing radiation at z=1.3, and it would strongly indicate that the
properties of galaxies at higher redshift have to be significantly
different for galaxies to dominate reionization. The deep FUV images
will also be useful for extending the FUV study of other galaxies in
the GOODS fields.

WFPC2 10787

Modes of Star Formation and Nuclear Activity in an Early Universe
Laboratory

Nearby compact galaxy groups are uniquely suited to exploring the
mechanisms of star formation amid repeated and ongoing gravitational
encounters, conditions similar to those of the high redshift universe.
These dense groups host a variety of modes of star formation, and they
enable fresh insights into the role of gas in galaxy evolution. With
Spitzer mid-IR observations in hand, we have begun to obtain high
quality, multi-wavelength data for a well- defined sample of 12 nearby
{4500km/s} compact groups covering the full range of evolutionary
stages. Here we propose to obtain sensitive BVI images with the
ACS/WFC, deep enough to reach the turnover of the globular cluster
luminosity function, and WFPC2 U-band and ACS H-alpha images of
Spitzer-identified regions hosting the most recent star formation. In
total, we expect to detect over 1000 young star clusters forming
inside and outside galaxies, more than 4000 old globular clusters in
40 giant galaxies {including 16 early-type galaxies}, over 20 tidal
features, approximately 15 AGNs, and intragroup gas in most of the 12
groups. Combining the proposed ACS images with Chandra observations,
UV GALEX observations, ground-based H-alpha imaging, and HI data, we
will conduct a detailed study of stellar nurseries, dust, gas
kinematics, and AGN.

WFPC2 10599

Multi-color imaging of two 1 Gyr old debris disks within 20 pc of the
Sun: Astrophysical mirrors of our Kuiper Belt

We report the first scattered light detections of two debris disk
around an F star and a K star using optical coronagraphy and the
Hubble Space Telescope. With ages ~1 Gyr, these are the oldest debris
disks thus far seen in the optical. We propose deep, multi-roll angle
coronagraphic imaging with HST ACS and NICMOS to confirm and
characterize the disks in terms of structure and composition. The
disks appear to have belt-like morphology that is consistent with the
existence of planetary companions or other perturbing bodies. Since
these disks are close to our Kuiper Belt in an evolutionary context,
detailed understanding of their mass, structure and composition will
provide a fresh perspective for inferring the history and properties
of our own trans-Neptunian region.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

********************** SCHEDULED***** SUCCESSFUL

FGS GSacq************** 23**************** 23
FGS REacq************** 18**************** 18
OBAD with Maneuver **** 82**************** 82

SIGNIFICANT EVENTS:

We've received the first internal flat-field images after reducing the
WFPC2 Replacement Heater temperature set points on Tuesday. Everything
looks good so far. The WF4 CCD bias levels are back in the 290 - 305
DN range, which is very close to normal. Changes in optical alignment
are small and in the expected range. All the images so far look
nominal.

We are reviewing additional calibration data, including images of the
star cluster Omega Cen, which should provide a good check on the image
quality. We'll update the status early this week.