Daily #4107

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4107

PERIOD COVERED: UT May 04, 2006 (DOY 124)

OBSERVATIONS SCHEDULED

ACS/HRC/WFC 10514

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 a
Snapshot program using the ACS/HRC that has a potential discovery
efficiency an order of magnitude higher than the HST observations that
have already discovered the majority of known transneptunian binaries.
By more than doubling the number of observed objects in dynamically
hot and cold subpopulations we will be able to answer, with
statistical significance, the question of whether these groups differ
in the abundance of binaries as a result 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.

ACS/WFC 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with
Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful
"dust free" Type Ia supernovae {SNe Ia} dataset than available with
the previous GOODS searches. Moreover, this approach provides a
strikingly more efficient search-and-follow-up that is primarily pre-
scheduled. The resulting dark energy measurements do not share the
major systematic uncertainty at these redshifts, that of the
extinction correction with a prior. By targeting massive galaxy
clusters at z 1 we obtain a five-times higher efficiency in
detection of Type Ia supernovae in ellipticals, providing a
well-understood host galaxy environment. These same deep cluster
images then also yield fundamental calibrations required for future
weak lensing and Sunyaev-Zel'dovich measurements of dark energy, as
well as an entire program of cluster studies. The data will make
possible a factor of two improvement on supernova constraints on dark
energy time variation, and much larger improvement in systematic
uncertainty. They will provide both a cluster dataset and a SN Ia
dataset that will be a longstanding scientific resource.

ACS/WFC 10503

The Star Formation Histories of Early Type Dwarf Galaxies in Low
Density Environments: Clues from the Sculptor Group

We seek HST ACS/WFC time to conduct a detailed study of the stellar
populations of 5 early-type {dE, dE/dIrr} dwarf galaxies in the nearby
{~1.5 to 4 Mpc} Sculptor group. Four of these systems have been
recently found to contain modest amounts of HI, and existing
ground-based and HST snapshot data point to the potential presence of
small populations of young {blue} stars in at least three of these
systems. Consequently, they resemble the Local Group 'transition'
objects Phoenix and LGS3. The relative number of such transition
systems is thus substantially larger in the low density environment of
the Scl group than for the Local Group. Detailed stellar populations
studies will allow estimation of the star formation histories, via
stellar population modelling of the color-magnitude diagrams, of the
target dwarfs, which in turn will connect to gas consumption and
retention rates. For the two nearer dwarfs we aim to reach below the
horizontal branch {a first for any system beyond the Local Group}
equivalent to a main sequence turnoff age of ~1 Gyr. The observations
of these two systems will also allow detection of RR Lyrae variables
and thus direct confirmation of the presence of old populations. For
the other three dwarfs will we cover the first 2.5 mags of the red
giant branch, equivalent to the main sequence termination for a ~300
Myr population. The results will have implications for theories of
galaxy formation and evolution, particularly with regard to the
evolutionary relation between low luminosity dEs and dwarf irregulars.

ACS/WFC 10592

An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in
the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared
selected galaxies exceeds that of optically selected galaxies. These
`luminous infrared galaxies' {LIRGs} are primarily interacting or
merging disk galaxies undergoing enhanced star formation and Active
Galactic Nuclei {AGN} activity, possibly triggered as the objects
transform into massive S0 and elliptical merger remnants. We propose
ACS/WFC imaging of a complete sample of 88 L_IR 10^11.4 L_sun
luminous infrared galaxies in the IRAS Revised Bright Galaxy Sample
{RBGS: i.e., 60 micron flux density 5.24 Jy}. This sample is ideal
not only in its completeness and sample size, but also in the
proximity and brightness of the galaxies. The superb sensitivity,
resolution, and field of view of ACS/WFC on HST enables a unique
opportunity to study the detailed structure of galaxies that sample
all stages of the merger process. Imaging will be done with the F439W
and F814W filters {B and I-band} to examine as a function of both
luminosity and merger state {i} the evidence at optical wavelengths of
star formation and AGN activity and the manner in which instabilities
{bars and bridges} in the galaxies may funnel material to these active
regions, {ii} the relationship between star formation and AGN
activity, and {iii} the structural properties {AGN, bulge, and disk
components} and fundamental parameters {effective radius and surface
brightness} of LIRGs and their similarity with putative evolutionary
byproducts {elliptical, S0 and classical AGN host galaxies}. This HST
survey will also bridge the wavelength gap between a Spitzer imaging
survey {covering seven bands in the 3.6-160 micron range} and a GALEX
UV imaging survey of these galaxies, but will resolve complexes of
star clusters and multiple nuclei at resolutions well beyond the
capabilities of either Spitzer or GALEX. The combined datasets will
result in the most comprehensive multiwavelength study of interacting
and merging galaxies to date.

ACS/WFC/HRC 10536

What Are Stalled Preplanetary Nebulae? An ACS SNAPshot Survey

Essentially all planetary nebulae {PNs} are aspherical, whereas the
mass-loss envelopes of AGB stars are strikingly spherical. Our
previous SNAPshot surveys of a morphologically unbiased sample of
pre-planetary nebulae {PPNs} -- objects in transition between the AGB
and PN evolutionary phases -- show that roughly half our observed
targets are resolved, with bipolar or multipolar morphologies.
Spectroscopic observations of our sample confirm that these objects
have not yet evolved into planetary nebulae. Thus, the transformation
from spherical to aspherical geometries has already fully developed by
the time these dying stars have become PPNs. Although our current
studies have yielded exciting results, they are limited in two
important ways -- {1} the number of well-resolved objects is still
small {18}, and the variety of morphologies observed relatively
multitudinous, hence no clear trends can yet be established between
morphology and other source properties {e.g., near-IR, far-IR colors,
stellar spectral type, envelope mass}, and {2} the current samples are
strongly biased towards small PPNs, as inferred from their low
60-to-25 micron flux ratios [R{60/25}1]. However, the prototype of
objects with R{60/25}1, the Frosty Leo Nebula, has a puzzlingly large
post-AGB age {almost 10^4 yr} and a fairly cool central star, very
different from the expectations of single-star stellar evolutionary
models. A proposed, but still speculative, hypothesis for such objects
is that the slow evolution of the central star is due to backflow of
material onto the mass-losing star, retarding its evolution towards
the PN phase. This hypothesis has significant consequences for both
stellar and nebular evolution. We therefore propose a survey of PPNs
with R{60/25}1 which is heavily weighted towards the discovery of
such "stalled PPNs". Supporting kinematic observations using long-slit
optical spectroscopy {with the Keck}, millimeter and radio
interferometric observations {with OVRO, VLA & VLBA} are being
undertaken. The results from this survey {together with our previous
work} will allow us to draw general conclusions about the complex
mass-outflow processes affecting late stellar evolution, and will
provide crucial input for theories of post-AGB stellar evolution. Our
survey will produce an archival legacy of long-standing value for
future studies of dying stars.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

10250 - OBAD Caused Inadvertent 10deg Maneuver @ 034/15:58:50z

An OBAD map/maneruver incorrectly identified a 10 deg attitude error
and maneuvered the spacecraft thus injecting a 10deg attitude error.
The subsequent OBAD correctly identified the error from the first OBAD
and maneuvered the spacecraft back to the correct attitude. The
sebsequent FGS acquisition was succesfull.

COMPLETED OPS REQUEST:
17747-1 - Battery 2 Capacity Test Script & 5 Battery Pressure Limit COP
(thru step 34) @ 124/2112z

17746-0 - Continuous Engineering Recording for Battery # 2 BCT @ Record
124/0944-1034z, Rewind 124/1050z, Record 124/1519-1622z, Record
124/1655-1756z, Rewind/TRINIT/Power off @ 124/1904z

17750-0 - CONTINGENCY: Disable ROC test for Battery 2 capacity test
@ DISABLE 124/1141z, ENABLE 124/1751z


COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 06 06
FGS REacq 08 08
OBAD with Maneuver 30 30


SIGNIFICANT EVENTS:

FLASH REPORT

(Thu, 4 May 2006 05:37:57, GWaldo) -- "Battery 2 Low-Rate Discharge
Termination" -- Battery 2 Capacity Test Flash Report -- Battery 2
low-rate discharge was completed on Thursday morning. Following
approximately 43 hours of total discharge time, the target low voltage
was reached and the reconditioning resistor was autonomously turned
off by HST486 FSW at 124/0844 GMT. EPS hardware reconfiguration was
completed during the orbit night period, with the reconnection of
solar array section 2 to battery 2 occurring at 124/0848 GMT.

FLASH REPORT

(Fri, 05 May 2006 00:26:38, EPS SE) - "Battery 2 Flash Report" --
Following placing Battery 2 back on-line in hardware at 124/0848 GMT,
the first Elevated VTFE - two orbit Boost was performed at 124/1151
GMT. The boost was autonomously terminated at 124/1503 GMT. Following
the completion of the first boost cycle, the battery temperatures
remained less than 5.3DegC. The second Elevated VTFE Boost was
performed at 124/1759 and autonomously terminated at 124/2113 GMT.
Battery temperatures increased ~2 DegC with battery 6 temperature
reaching 6.85 DegC. As of 125/0020, the battery temperatures were
continuing to trend downward with battery 5 the highest at 4.26 DegC.
EPS SEs are scheduled to place battery back on-line in hardware at
~125/1630 GMT (Friday, May 5th 12:30pm local).

Intercept SMS for target of opportunity (Proposal # 10624 - "Solving
the Mystery of the Short-Hard Gamma-Ray Bursts"), command loader
SA121Q03_F1, authorized @ 124/22:59:47z