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      # 4364

PERIOD COVERED: UT May 16, 2007 (DOY 136)

OBSERVATIONS SCHEDULED

WFPC2 10800

Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have

relatively fragile test particles which can be used as tracers of the

early dynamical evolution of the outer Solar System. We propose to

continue a Snapshot program using the ACS/HRC that has a demonstrated

discovery potential an order of magnitude higher than the HST

observations that have already discovered the majority of known

transneptunian binaries. With this continuation we seek to reach the

original goals of this project: to accumulate a sufficiently large

sample in each of the distinct populations collected in the Kuiper Belt

to be able to measure, with statistical significance, how the fraction

of binaries varies as a function of their particular dynamical paths

into the Kuiper Belt. Today's Kuiper Belt bears the imprints of the

final stages of giant-planet building and migration; binaries may offer

some of the best preserved evidence of that long-ago era.

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 10799

Photometric Mapping of Vesta's Southern Hemisphere

We propose to image asteroid 4 Vesta throughout one complete rotation

during its opposition and close approach to Earth in May of 2007 in four

filters for the purposes of improving knowledge of its spin pole, size,

shape, albedo and composition across its surface. We will conduct a

satellite search. Multi-filter imaging will extend the range of

photometric mapping into the southern hemisphere where a large basin

exists, and will extend compositional mapping further into the southern

hemisphere than previous observations. The results will improve our

understanding of protoplanetary processes and support scientific

planning for NASA's Dawn mission to orbit Vesta 2011.

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               10                  10            

FGS REacq               02                  02               

OBAD with Maneuver 24                  24              

SIGNIFICANT EVENTS: (None)