Daily Report # 4382

Notice: For the foreseeable future, the daily reports may contain apparent
discrepancies between some proposal descriptions and the listed instrument
usage. This is due to the conversion of previously approved ACS WFC or HRC
observations into WFPC2, or NICMOS observations subsequent to the loss of
ACS CCD science capability in late January.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4382

PERIOD COVERED: UT June 12, 2007 (DOY 163)

OBSERVATIONS SCHEDULED

WFPC2 10880

The host galaxies of QSO2s: AGN feeding and evolution at high luminosities

Now that the presence of supermassive black holes in the nuclei of galaxies
is a well established fact, other questions related to the AGN phenomena
still have to be answered. Problems of particular interest are how the AGN
gets fed, how the black hole evolves and how the evolution of the black hole
is related to the evolution of the galaxy bulge. Here we propose to address
some of these issues using ACS/WFC + F775W snapshot images of 73 QSO2s with
redshifts in the range 0.3z0.4. These observations will be combined with
similar archival data of QSO1s and ground based data of Seyfert and normal
galaxies. First, we will intestigate whether interactions are the most
important feeding mechanism in high luminosity AGNs. This will be done in a
quantitative way, comparing the asymmetry indices of QSO2 hosts with those
of lower luminosity AGNs and normal galaxies. Second, we will do a detailed
study of the morphology of the host galaxies of both QSO types, to determine
if they are similar, or if there is an evolutionary trend from QSO2s to
QSO1s. The results from this project will represent an important step in the
understanding of AGN evolution, and may also introduce a substantial
modification to the Unified Model.

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 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.

NIC2 11157

NICMOS Imaging Survey of Dusty Debris Around Nearby Stars Across the Stellar
Mass Spectrum

Association of planetary systems with dusty debris disks is now quite
secure, and advances in our understanding of planet formation and evolution
can be achieved by the identification and characterization of an ensemble of
debris disks orbiting a range of central stars with different masses and
ages. Imaging debris disks in starlight scattered by dust grains remains
technically challenging so that only about a dozen systems have thus far
been imaged. A further advance in this field needs an increased number of
imaged debris disks. However, the technical challege of such observations,
even with the superb combination of HST and NICMOS, requires the best
targets. Recent HST imaging investigations of debris disks were
sample-limited not limited by the technology used. We performed a search for
debris disks from a IRAS/Hipparcos cross correlation which involved an
exhaustive background contamination check to weed out false excess stars.
Out of ~140 identified debris disks, we selected 22 best targets in terms of
dust optical depth and disk angular size. Our target sample represents the
best currently available target set in terms of both disk brightness and
resolvability. For example, our targets have higher dust optical depth, in
general, than newly identified Spitzer disks. Also, our targets cover a
wider range of central star ages and masses than previous debris disk
surveys. This will help us to investigate planetary system formation and
evolution across the stellar mass spectrum. The technical feasibility of
this program in two-gyro mode guiding has been proven with on- orbit
calibration and science observations during HST cycles 13, 14, and 15.

WFPC2 11079

Treasury Imaging of Star Forming Regions in the Local Group: Complementing
the GALEX and NOAO Surveys

We propose to use WFPC2 to image the most interesting star-forming regions
in the Local Group galaxies, to resolve their young stellar populations. We
will use a set of filters including F170W, which is critical to detect and
characterize the most massive stars, to whose hot temperatures colors at
longer wavelengths are not sensitive. WFPC2's field of view ideally matches
the typical size of the star-forming regions, and its spatial resolution
allows us to measure indvidual stars, given the proximity of these galaxies.
The resulting H- R diagrams will enable studies of star-formation properties
in these regions, which cover largely differing metallicities {a factor of
17, compared to the factor of 4 explored so far} and characteristics. The
results will further our understanding of the star-formation process, of the
interplay between massive stars and environment, the properties of dust, and
will provide the key to interpret integrated measurements of star-formation
indicators {UV, IR, Halpha} available for several hundreds more distant
galaxies. Our recent deep surveys of these galaxies with GALEX {FUV, NUV}
and ground-based imaging {UBVRI, Halpha, [OIII] and [SII]} provided the
identification of the most relevant SF sites. In addition to our scientific
analysis, we will provide catalogs of HST photometry in 6 bands, matched
corollary ground-based data, and UV, Halpha and IR integrated measurements
of the associations, for comparison of integrated star-formation indices to
the resolved populations. We envisage an EPO component.

WFPC2 11081

RR Lyrae stars in M31 Globular Clusters: How did the M31 Spiral Galaxy Form?

The pulsation properties of the RR Lyrae stars in the globular clusters of
the Andromeda galaxy {M31} have the potential to provide essential insight
on the first epoch of the galaxy formation and to trace the merging episodes
that led to the assembly of M31. Their mean periods along with the cluster
metallicities can provide an independent estimate of the M31 cluster ages
and, in turn, of the time scale of the M31 halo formation, by comparison
with their Milky Way counterparts. We will observe RR Lyrae stars in 6
appropriately selected globular clusters of M31 using WFPC2 to derive
periods, light curves, and physical parameters of these eyewitnesses of the
first epochs of the M31 formation.

WFPC2 11083

The Structure, Formation and Evolution of Galactic Cores and Nuclei

A surprising result has emerged from the ACS Virgo Cluster Survey {ACSVCS},
a program to obtain ACS/WFC gz imaging for a large, unbiased sample of 100
early-type galaxies in the Virgo Cluster. On subarcsecond scales {i.e.,
0.1"-1"}, the HST brightness profiles vary systematically from the
brightest giants {which have nearly constant surface brightness cores} to
the faintest dwarfs {which have compact stellar nuclei}. Remarkably, the
fraction of galaxy mass contributed by the nuclei in the faint galaxies is
identical to that contributed by supermassive black holes in the bright
galaxies {0.2%}. These findings strongly suggest that a single mechanism is
responsible for both types of Central Massive Object: most likely internally
or externally modulated gas inflows that feed central black holes or lead to
the formation of "nuclear star clusters". Understanding the history of gas
accretion, star formation and chemical enrichment on subarcsecond scales has
thus emerged as the single most pressing question in the study of nearby
galactic nuclei, either active or quiescent. We propose an ambitious HST
program {199 orbits} that constitutes the next, obvious step forward:
high-resolution, ultraviolet {WFPC2/F255W} and infrared {NIC1/F160W} imaging
for the complete ACSVCS sample. By capitalizing on HST's unique ability to
provide high-resolution images with a sharp and stable PSF at UV and IR
wavelengths, we will leverage the existing optical HST data to obtain the
most complete picture currently possible for the history of star formation
and chemical enrichment on these small scales. Equally important, this
program will lead to a significant improvement in the measured structural
parameters and density distributions for the stellar nuclei and the
underlying galaxies, and provide a sensitive measure of "frosting" by young
stars in the galaxy cores. By virtue of its superb image quality and stable
PSF, NICMOS is the sole instrument capable of the IR observations proposed
here. In the case of the WFPC2 observations, high-resolution UV imaging {
0.1"} is a capability unique to HST, yet one that could be lost at any any
time.

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 04 04
FGS REacq 11 11
OBAD with Maneuver 29 29

SIGNIFICANT EVENTS: (None)