Daily # 4190

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4190

PERIOD COVERED: UT August 31, 2006 (DOY 243)

OBSERVATIONS SCHEDULED

ACS/HRC 10738

Earth Flats

Sky flats will be obtained by observing the bright Earth with the HRC
and WFC. These observations will be used to verify the accuracy of the
flats currently in the pipeline and to monitor any changes. Weekly
coronagraphic monitoring is required to assess the changing position
of the spots.

ACS/HRC 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.

ACS/HRC 10870

The Ring Plane Crossings of Uranus in 2007

The rings of Uranus turn edge-on to Earth in May and August 2007. In
between, we will have a rare opportunity to see the unlit face of the
rings. With the nine optically thick rings essentialy invisible, we
will observe features and phenomena that are normally lost in their
glare. We will use this opportunity to search thoroughly for the
embedded "shepherd" moons long believed to confine the edges of the
rings, setting a mass limit roughly 10 times smaller than that of the
smallest shepherd currently known, Cordelia. We will measure the
vertical thicknesses of the rings and study the faint dust belts only
known to exist from a single Voyager image. We will also study the
colors of the newly-discovered faint, outer rings; recent evidence
suggests that one ring is red and the other blue, implying that each
ring is dominated by a different set of physical processes. We will
employ near-edge-on photometry from 2006 and 2007 to derive the
particle filling factor within the rings, to observe how ring epsilon
responds to the "traffic jam" as particles pass through its narrowest
point, and to test the latest models for preserving eccentricities and
apse alignment within the rings. Moreover, this data set will allow us
to continue monitoring the motions of the inner moons, which have been
found to show possibly chaotic orbital variations; by nearly doubling
the time span of the existing ACS astrometry, the details of the
variations will become much clearer.

ACS/HRC 10878

An ACS Prism Snapshot Survey for z~2 Lyman Limit Systems

We propose to conduct a spectroscopic survey of Lyman limit absorbers
at redshifts 1.7 z 2.2, using ACS/HRC and the PR200L prism. We
have selected 100 quasars at 2.3 z 2.6 from the Sloan Digital Sky
Survey Spectroscopic Quasar sample, for which no BAL signature is
found at the QSO redshift and no strong metal absorption lines are
present at z 2.3 along the lines of sight. The survey has three main
observational goals. First, we will determine the redshift frequency
dN/dz of the LLS over the column density range 16.3 log N_HI 20.3
cm^-2. Second, we will measure the column density frequency
distribution f{N} for the partial Lyman limit systems {PLLS} over the
column density range 16.3 log N_HI 17.5 cm^-2. Third, we will
identify new sightlines for measurements of the primordial D/H ratio.
With this survey, we will also constrain two key quantities of
cosmological relevance: First, the measurements of dN/dz for optically
thick LLS and f{N} for the PLLS are critical to estimating the
attenuation of extragalactic ionizing sources {e.g. QSOs}. Currently,
uncertainties in dN/dz and f{N} are the greatest sources of
uncertainty for inferring the shape and intensity of the UV background
radiation field. Second, we will estimate the amount of metals in the
LLS using the f{N} and ground based observations of metal line
transitions. It is possible that a significant fraction of the
"missing metals" at z~2 are associated with these highly ionized
absorbers. Third, analysis of the LLS lends to investigations of the
interface between galaxies {i.e. the damped Lyman alpha systems} and
the intergalactic medium {i.e. the Lyman alpha forest}. This survey is
ideal for a snapshot observing program, because the on-object
integration times are less than 10 minutes, and the targets cover the
majority of the northern sky.

ACS/HRC/WFC 10570

Hosts of Quasars with Opaque Partial Covering

A few quasars are known to exhibit associated absorption lines with
opaque partial covering. These are the lines which are clearly
saturated but not completely dark, so that these absorbing clouds are
opaquely and partially covering the quasar light. In some cases,
ionization parameter and density arguments indicate that the absorbers
are on kpc scale. This implies that at least in some cases, the
residual, unabsorbed optical {rest-UV} continuum component originates
from ~kpc scales, rather than microscopic scales {such as ~100
Schwarzschild radii}. This could be a superluminous host galaxy or
starbursting core, and could be resolved by HST. We address the nature
of these opaquely and partially covered quasars with a simple and
robust ACS imaging.

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/NIC3 10632

Searching for galaxies at z6.5 in the Hubble Ultra Deep Field

We propose to obtain deep ACS {F606W, F775W, F850LP} imaging in the
area of the original Hubble Ultra Deep Field NICMOS parallel fields
and - through simultaneous parallel observations - deep NICMOS {F110W,
F160W} imaging of the ACS UDF area. Matching the extreme imaging depth
in the optical and near-IR bands will result in seven fields with
sufficiently sensitive multiband data to detect the expected typical
galaxies at z=7 and 8. Presently no such a field exist. Our combined
optical and near-IR ultradeep fields will be in three areas separated
by about 20 comoving Mpc at z=7. This will allow us to give a first
assessment of the degree of cosmic variance. If reionization is a
process extending over a large redshift interval and the luminosity
function doesn't evolve strongly beyond z=6, these data will allow us
to identify of the order of a dozen galaxies at 6.5z8.5 - using the
Lyman break technique - and to place a first constrain on the
luminosity function at z6.5. Conversely, finding fewer objects would
be an indication that the bulk of reionization is done by galaxies at
z=6. By spending 204 orbits of prime HST time we will capitalize on
the investment of 544 prime orbits already made on the Hubble Ultra
Deep Field {UDF}. We have verified that the program as proposed is
schedulable and that it will remain so even if forced to execute in
the 2-gyro mode. The data will be non-proprietary and the reduced
images will be made public within 2 months from the completion of the
observations.

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

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. The keyword 'USEAFTER=date/time' will also be added to
the header of each POST-SAA DARK frame. The keyword must be populated
with the time, in addition to the date, because HST crosses the SAA ~8
times per day so each POST-SAA DARK will need to have the appropriate
time specified, for users to identify the ones they need. Both the raw
and processed images will be archived as POST-SAA DARKSs. Generally we
expect that all NICMOS science/calibration observations started within
50 minutes of leaving an SAA will need such maps to remove the CR
persistence from the science images. Each observation will need its
own CRMAP, as different SAA passages leave different imprints on the
NICMOS detectors.

NIC2 10519

Testing the Stellar Coalescence and Accretion Disk Theories of Massive
Star Formation with NICMOS

The importance of massive stars cannot be underestimated - they
produce most of the heavy elements in the universe and dominate the
evolution of the interstellar medium in their vicinity. In spite of
their significance, our understanding of their formation is meager.
Both accretion through disks, analogous to the process of low-mass
star formation, and coalescence of low-mass stars through collisions
in the dense cores of stellar clusters have been suggested. Possibly
both mechanisms occur. High spatial resolution polarization
measurements of the closest massive young stellar objects {YSOs} will
enable us to search for evidence of disk accretion or coalescence in
the form of patterns indicative of light scattered off a coherent disk
or off a disk disrupted by an infalling star, respectively. Here we
propose to use 2 micron polarimetry with NICMOS to identify the
presence of accretion disks around massive YSOs or to characterize
their environments as possibly disrupted from a close stellar
encounter. There are only a few sources that meet the stringent
selection criteria for this investigation {even with HST}, which we
will examine here. High spatial resolution is required, but even more
important, the point spread function {PSF} must be stable with time.
Furthermore, the PSF must put minimal flux into large spatial scales,
something that cannot be achieved with adaptive optics. This
combination of high Strehl ratio and stable PSF can only be achieved
from space.

NIC2 10527

Imaging Scattered Light from Debris Disks Discovered by the Spitzer
Space Telescope Around 20 Sun-like Stars

We propose to use the high contrast capability of the NICMOS
coronagraph to image a sample of newly discovered circumstellar disks
associated with sun-like stars. These systems were identified by their
strong thermal infrared emission with the Spitzer Space Telescope as
part of the Spitzer Legacy Science program titled, "The Formation and
Evolution of Planetary Systems {FEPS}." Modelling of the thermal
excess emission in the form of spectral energy distributions alone
cannot distinguish between narrowly confined high opacity disks and
broadly distributed, low opacity disks. However, our proposed NICMOS
observations can, by imaging the light scattered from this material.
Even non- detections will place severe constraints on the disk
geometry, ruling out models with high optical depth. Unlike previous
disk imaging programs, our program contains a well defined sample of
solar mass stars covering a range of ages from ~10Myrs to a few Gyrs,
allowing us to study the evolution of disks from primordial to debris
for the first time. These results will greatly improve our
understanding of debris disks around Sun- like stars at stellar ages
nearly 10x older than any previous investigation. Thus we will have
fit a crucial piece into the puzzle concerning the formation and
evolution of our own solar system.

S/C 4974

TRTTEST

The Transcient Response Test is for the periodic performance
monitoring of the FGS 2R servo A mechanism.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10413 - GSAcq(1,3,3) Failed to RGA Control

At acquisition of signal 243/19:59:33, the GSAcq(1,3,3) scheduled at
243/19:39:30 - 19:47:34 was observed to have failed to RGA Hold, due
to stop flag (QF1STOPF) indication on FGS-1. Pre-acquisition OBADs
(RSS) attitude correction values not available due to LOS.
Post-acquisition OBAD/MAP at 243/19:47:33 had 3-axis (RSS) error
correction value of 4.86 arcseconds.

10414 - GSAcq (2,3,3) failed due to search radius limit exceeded on
FGS 2

At AOS 244/02:18:37, GSAcq (2.3.3) scheduled at 244/01:42:54 -
01:50:11, had failed due to search radius limit exceeded on FGS 2.
Previous OBAD's were unavailable due to LOS. OBAD MAP showed RSS value
of 84.30 a-s. Performed 486 STB dump which showed STB message "a05",
exceeded SRL was received at 244/01:47:43.

10415 - REAcq (2,3,3) failed to start

GSAcq (2,3,3) scheduled at 244/08:04:15 failed to start. No flags were
observed. Pre-Acq OBAD's RSS values were 1273.36 and 60.37 a-s. Post
Acq OBAD Map showed RSS value of 19.16 a-s.

COMPLETED OPS REQUEST:
17911-2 - TRT Test # 12 @ 243/1344z
17914-1 - Genslew for proposal 10539 - slot 4 @ 243/2045z
17915-0 - Genslew for proposal 10539 - slot 5 @ 243/2047z
17916-0 - Genslew for proposal 10539 - slot 6 @ 243/2049z


COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 08 06
FGS REacq 05 04
OBAD with Maneuver 30 30

SIGNIFICANT EVENTS:

Flash Report: TRTT Successful

The 12th iteration of the Transient Rate Trending Test (TRTT) was
successfully completed at 243/13:44z via Ops Request 17911. The
analysis will be completed by OTA SEs and will be presented at the
Guide Star Acq Working Group meeting on September 11.