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Daily Report # 4365



 
 
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Old May 18th 07, 04:09 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report # 4365

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 0.3z0.4. 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.

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)
 




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