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 # 4365
PERIOD COVERED: UT May 17, 2007 (DOY 137)
OBSERVATIONS SCHEDULED
WFPC2 10832
Solving the microlensing puzzle: An HST high-resolution
imaging approach
We propose to use the HST Advanced Camera for Surveys High
Resolution
Channel to obtain high resolution imaging data for 10
bona-fide LMC
microlensing events seen in the original MACHO survey. The
purpose of
this survey will be to assess whether or not the lens and
source stars
have separated enough to be resolved since the original
microlensing
event took place - about a decade has passed since the
original MACHO
survey and the HST WFPC2 follow-up observations of the
microlensing
events. If the components of the lensing event are
resolved, we will
determine the apparent magnitude and color of both the
lens and the
source stars. These data, in combination with Spitzer/IRAC
data and
Magellan near-IR JHK data, will be used to ascertain the
basic
properties of the lens stars. With the majority of the
microlensing
events in the original MACHO survey observed at the
highest spatial
resolution currently possible, we will be able to draw
important
conclusions as to what fraction of these events have
lenses which belong
to some population of dwarf stars in the disk and what
fraction must be
due to lenses in the halo or beyond. These data will
greatly increase
our understanding of the structure of the Galaxy by
characterizing the
stellar population responsible for the gravitational
microlensing.
ACS/SBC 10862
Comprehensive Auroral Imaging of Jupiter and Saturn during
the
International Heliophysical Year A comprehensive set of
observations of
the auroral emissions from Jupiter and Saturn is proposed
for the
International Heliophysical Year in 2007, a unique period
of especially
concentrated measurements of space physics phenomena
throughout the
solar system. We propose to determine the physical
relationship of the
various auroral processes at Jupiter and Saturn with
conditions in the
solar wind at each planet. This can be accomplished with
campaigns of
observations, with a sampling interval not to exceed one day,
covering
at least one solar rotation. The solar wind plasma density
approaching
Jupiter will be measured by the New Horizons spacecraft,
and a separate
campaign near opposition in May 2007 will determine the
effect of
large-scale variations in the interplanetary magnetic
field {IMF} on the
Jovian aurora by extrapolation from near-Earth solar wind
measurements.
A similar Saturn campaign near opposition in Jan. 2007
will combine
extrapolated solar wind data with measurements from a wide
range of
locations within the Saturn magnetosphere by Cassini. In
the course of
making these observations, it will be possible to fully
map the auroral
footprints of Io and the other satellites to determine
both the local
magnetic field geometry and the controlling factors in the
electromagnetic interaction of each satellite with the
corotating
magnetic field and plasma density. Also in the course of
making these
observations, the auroral emission properties will be
compared with the
properties of the near-IR ionospheric emissions {from
ground-based
observations} and non thermal radio emissions, from
ground-based
observations for Jupiter?s decametric radiation and
Cassini plasma wave
measurements of the Saturn Kilometric Radiation {SKR}.
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
0.3<z<0.4. 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.
WFPC2 10889
The Nature of the Halos and Thick Disks of Spiral Galaxies
We propose to resolve the extra-planar stellar populations
of the thick
disks and halos of seven nearby, massive, edge-on galaxies
using ACS,
NICMOS, and WFPC2 in parallel. These observations will
provide accurate
star counts and color-magnitude diagrams 1.5 magnitudes
below the tip of
the Red Giant Branch sampled along the two principal axes
and one
intermediate axis of each galaxy. We will measure the
metallicity
distribution functions and stellar density profiles from
star counts
down to very low average surface brightnesses, equivalent
to ~32 V-mag
per square arcsec. These observations will provide the
definitive HST
study of extra-planar stellar populations of spiral
galaxies. Our
targets cover a range in galaxy mass, luminosity, and
morphology and as
function of these galaxy properties we will provide: - The
first
systematic study of the radial and isophotal shapes of the
diffuse
stellar halos of spiral galaxies - The most detailed
comparative study
to date of thick disk morphologies and stellar populations
- A
comprehensive analysis of halo and thick disk metallicity
distributions
as a function of galaxy type and position within the
galaxy. - A
sensitive search for tidal streams - The first opportunity
to directly
relate globular cluster systems to their field stellar
population We
will use these fossil records of the galaxy assembly
process preserved
in the old stellar populations to test halo and thick disk
formation
models within the hierarchical galaxy formation scheme. We
will test
LambdaCDM predictions on sub-galactic scales, where it is
difficult to
test using CMB and galaxy redshift surveys, and where it
faces its most
serious difficulties.
WFPC2 10903
Resolving the LMC Microlensing Puzzle: Where are the
Lensing Objects?
We are requesting 12 HST orbits to continue to investigate
the nature of
the population that gives rise to the microlensing seen
towards the LMC.
This proposal builds on the cycle 14 HST program {10583}
and will
complement the study with 12 yet-to-be discovered
microlensing
candidates from Fall 2006. Our SuperMacho project is an
ongoing ground-
based survey on the CTIO 4m that has demonstrated the ability
to detect
LMC microlensing events via frame subtraction. The
combination of high
angular resolution and photometric accuracy with HST will
allow us to 1}
confrim that the detected flux excursions arise from LMC
stars, rather
than background supernovae or AGN, and 2} obtain reliable
baseline flux
measurements for the objects in their unlensed state. This
latter
measurement in important in determining the microlensing
optical depth
towards the LMC.
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
08
08
FGS
REacq
04
04
OBAD with Maneuver
24
24
SIGNIFICANT EVENTS: (None)