Daily 4119

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4119

PERIOD COVERED: UT May 22, 2006 (DOY 142)

OBSERVATIONS SCHEDULED

ACS/HRC 10512

Search for Binaries Among Faint Jupiter Trojan Asteroids

We propose an ambitious SNAPSHOT program to survey faint Jupiter
Trojan asteroids for binary companions. We target 150 objects, with
the expectation of acquiring data on about 50%. These objects span
Vmag = 17.5-19.5, a range inaccessible with ground-based adaptive
optics. We now have a significant sample from our survey of brighter
Trojans to suggest that the binary fraction is similar to that which
we find among brighter main-belt asteroids, roughly 2%. However, our
observations suggest a higher binary fraction for smaller main-belt
asteroids, probably the result of a different formation mechanism
{evident also from the physical characteristics of the binaries}.
Because the collision environment among the Trojans is similar to that
of the Main Belt, while the composition is likely to be very
different, sampling the binary fraction among the fainter Trojans
should help us understand the collisional and binary formation
mechanisms at work in various populations, including the Kuiper Belt,
and help us evaluate theories for the origin of the Trojans.
Calibration of and constraints on models of binary production and
collisional evolution can only be done using these large-scale,
real-life physical systems that we are beginning now to find and
utilize.

ACS/HRC 10525

Characterizing the Near-UV Environment of M Dwarfs: Implications for
Extrasolar Planetary Searches and Astrobiology

We propose SNAP observations with the ACS HRC PR200L prism, designed
to measure the near ultraviolet emission in a sample of 107 nearby M
dwarfs. The sample spans the mass range from 0.1 - 0.6 solar masses
{temperature range 2200K - 4000K} where the UV energy distributions
vary widely between active and inactive stars. The strength and
distribution of this UV emission can have critical consequences for
the atmospheres of attendant planets. Our proposed observations will
provide desperately needed constraints on models of the habitability
zone and the atmospheres of possible terrestrial planets orbiting M
dwarf hosts, and will be used to sharpen TPF target selection. In
addition, the NUV data will be used in conjunction with existing
optical, FUV and X-ray data to constrain a new generation of M dwarf
atmospheric models, and to explore unanswered questions regarding the
dynamo generation and magnetic heating in these low-mass stars.

ACS/HRC 10923

Measuring the size of the close-in transiting extrasolar planet HD
189733b

A new transiting exoplanet was found by our radial velocity search
around the bright K dwarf HD 189733. With an apparent V magnitude of
7.67 and a distance of 19 pc, it is the closest star known with a
transiting extrasolar planet. Moreover, the high radius ratio {Rpl/R ~
0.17} makes it a uniquely favorable target for exoplanet studies. This
planet is set to become the most observed hot Jupiter and a landmark
in the understanding of hot Jupiter structure and formation. We
propose a fundamental observations with the HST: to measure precisely
the size of the transiting planet around HD189733 and the inclination
angle of its orbit. The radius is an important characteristic of the
planet in itself. A precise, model-independent radius determination is
also a necessary prerequisite for further observations of the system
with ground-based large telescopes and Spitzer {e.g. to detect
reflected light and intrinsic infrared light from the planet, to
measure the Rossiter-McLaughlin effect}. This observation requires a
high-accuracy spectrophotometry light curve with ACS in the visible.
Similar observations for the formerly closest transiting planet, HD
209458b, have revealed that the planet was much larger than accounted
for by any model, and undergoing strong evaporation, two observations
that have had a profound impact on our understanding of the structure
of close-in exoplanets and the migration process.

ACS/HRC/WFC 10737

CCD Stability Monitor

This program will verify that the low frequency flat fielding, the
photometry, and the geometric distortion are stable in time and across
the field of view of the CCD detectors. A moderately crowded stellar
field in the cluster 47 Tuc is observed every three months with the
HRC {at the cluster core} and WFC {6' West of the cluster core} using
the full suite of broad and narrow band imaging filters. The positions
and magnitudes of objects will be used to monitor local and large
scale variations in the plate scale and the sensitivity of the
detectors and to derive an independent measure of the detector CTE. An
additional orbit is required to compare WFC observations taken at gain
1 with those taken at the new default gain 2.

ACS/HRC/WFC 10758

ACS CCDs daily monitor

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This programme will be
for the entire lifetime of ACS. Changes from cycle 13:- The default
gain for WFC is 2 e-/DN. As before bias frames will be collected for
both gain 1 and gain 2. Dark frames are acquired using the default
gain {2}. This program cover the period May, 31 2006- Oct, 1-2006. The
first half of the program has a different proposal number: 10729.

ACS/WFC 10491

A Snapshot Survey of the most massive clusters of galaxies

We propose a snapshot survey of a sample of 124 high X-ray luminosity
clusters in the redshift range 0.3-0.7. Similarly luminous clusters at
these redshifts frequently exhibit strong gravitational lensing. The
proposed observations will provide important constraints on the nature
of the cluster mass distributions and a set of optically bright,
lensed galaxies for further 8-10m spectroscopy. We acknowledge the
broad community interest in this sample and waive our data rights for
these observations.

ACS/WFC 10775

An ACS Survey of Galactic Globular Clusters

We propose to conduct an ACS/WFC imaging survey of Galactic globular
clusters. We will construct the most extensive and deepest set of
photometry and astrometry to-date for these systems reaching a main
sequence mass of ~0.2 solar mass with S/N = 10. We will combine these
data with archival WFPC2 and STIS images to determine proper motions
for the stars in our fields. The resultant cleaned cluster CMDs will
allow us to study a variety of scientific questions. These include
[but are not limited to] 1} the determination of cluster ages and
distances 2} the construction of main sequence mass functions and the
issue of mass segregation 3} the internal motions and dynamical
evolution of globular clusters, and 4} absolute cluster motions,
orbits, and the Milky Way gravitational potential. We anticipate that
the unique resource provided by the proposed treasury archive will
play a central role in the field of globular cluster studies for
decades, with a stature comparable to that of the Hubble Deep Field
for high redshift studies.

FGS 10611

Precise Distances to Nearby Planetary Nebulae

We propose to carry out astrometry with the FGS to obtain accurate and
precise distances to four nearby planetary nebulae. In 1992, Cahn et
al. noted that ``The distances to Galactic planetary nebulae remain a
serious, if not THE most serious, problem in the field, despite
decades of study.'' Twelve years later, the same statement still
applies. Because the distances to planetary nebulae are so uncertain,
our understanding of their masses, luminosities, scale height, birth
rate, and evolutionary state is severely limited. To help remedy this
problem, HST astrometry can guarantee parallaxes with half the error
of any other available approach. These data, when combined with
parallax measurements from the USNO, will improve distance
measurements by more than a factor of two, producing more accurate
distances with uncertainties that are of the order of ~6%. Lastly,
most planetary nebula distance scales in the literature are
statistical. They require several anchor points of known distance in
order to calibrate their zero point. Our program will provide "gold
standard" anchor points by the end of 2006, a decade before any
anticipated results from future space astrometry missions.

NICMOS 8790

NICMOS Post-SAA calibration - CR Persistence Part 1.

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.

WFPC2 10628

Determining the Lifetime of Planetary Nebula Knots from Observations
of the Core of the Helix Nebula.

Knots within the Planetary Nebulae {PN} are ubiquitous components and
form at the interface of the expanding ionized zone and the
surrounding dusty and molecule-rich neutral layers. About half of the
total mass ejected by the precursor star becomes trappped in the
Knots, which will join the Interstellar Medium {ISM} within a few tens
of thousands of years. If they survive, they may be the source of the
micro-structures that appear to be common in the ISM, a result that
would be important in understanding the exchange of matter between
stars and the ISM. We propose observations that will characterize the
Knots over a wider ionization range and ages than has been done
before, which should yield the best model for the Knots and therefore
the best prediction of their fates. Knots are not seen within a well
defined distance from the central star. We don't know if this is
because they are being destroyed by photoevaporation {since the inner
Knots would be the youngest}, an important factor in our modeling.
However, the inner core of the Helix Nebula has not been imaged in the
HeII emission that dominates the region. We propose eight orbits of
observations that will search the inner core of the Helix for
undetected knots using the WFPC2 HeII F469N filter and the ACS-WFC
F502N filter that isolates [OIII] emission. Our WFPC2 pointing will
also allow imaging the best studied knot in HeII, giving us the best
possible data for that Knot. These combined results will be modeled
with the new Hydro- Cloudy code, allowing us to determine if they will
survive the PN stage and become components of the ISM. At no
additional cost of observing time we will be able to derive a
calibration of the WFPC2 F469N filter, to make unprecedented quality
parallel images in molecular hydrogen, and to extended the coverage of
high resolution emission-line images of the Helix Nebula.

WFPC2 10748

WFPC2 CYCLE 14 Standard Darks

This dark calibration program obtains dark frames every week in order
to provide data for the ongoing calibration of the CCD dark current
rate, and to monitor and characterize the evolution of hot pixels.
Over an extended period these data will also provide a monitor of
radiation damage to the CCDs.

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 09 09
FGS REacq 05 05
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)