Daily # 4245

Daily Report # 4246 will appear on Monday, November 27

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4245

PERIOD COVERED: UT November 21, 2006 (DOY 325)

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 11011

Dissecting An Accretion Disk

We will use 5 epochs of CXO and HST imaging to determine the X-ray and
UV size of the accretion disk of the lensed quasar RXJ1131--1231 using
microlensing. Based on preliminary data, we find that the X-ray source
is roughly 1/10 the size of the accretion disk in the rest- frame
B-band. The new observations will significantly reduce the
uncertainties in this estimate, provide a comparison between the size
of the X-ray source and the size of the accretion disk in the rest
frame ultraviolet, and have the signal-to-noise ratio necessary to
begin examining the size of the hard and soft-band X-ray emission
regions separately. The results will quantitatively test accretion
disk theory and X-ray emission mechanisms.

ACS/WFC 10787

Modes of Star Formation and Nuclear Activity in an Early Universe
Laboratory

Nearby compact galaxy groups are uniquely suited to exploring the
mechanisms of star formation amid repeated and ongoing gravitational
encounters, conditions similar to those of the high redshift universe.
These dense groups host a variety of modes of star formation, and they
enable fresh insights into the role of gas in galaxy evolution. With
Spitzer mid-IR observations in hand, we have begun to obtain high
quality, multi-wavelength data for a well-defined sample of 12 nearby
{4500km/s} compact groups covering the full range of evolutionary
stages. Here we propose to obtain sensitive BVI images with the
ACS/WFC, deep enough to reach the turnover of the globular cluster
luminosity function, and WFPC2 U-band and ACS H-alpha images of
Spitzer- identified regions hosting the most recent star formation. In
total, we expect to detect over 1000 young star clusters forming
inside and outside galaxies, more than 4000 old globular clusters in
40 giant galaxies {including 16 early-type galaxies}, over 20 tidal
features, approximately 15 AGNs, and intragroup gas in most of the 12
groups. Combining the proposed ACS images with Chandra observations,
UV GALEX observations, ground-based H-alpha imaging, and HI data, we
will conduct a detailed study of stellar nurseries, dust, gas
kinematics, and AGN.

ACS/WFC 11045

ACS internal CTE monitor

The charge transfer efficiency {CTE} of the ACS CCD detectors will
decline as damage due to on-orbit radiation exposure accumulates. This
degradation will be closely monitored at regular intervals, because it
is likely to determine the useful lifetime of the CCDs. All the data
for this program is acquired using internal targets {lamps} only, so
all of the exposures should be taken during Earth occultation time
{but not during SAA passages}. This program emulates the ACS
pre-flight ground calibration and post-launch SMOV testing {program
8948}, so that results from each epoch can be directly compared.
Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}
data will be obtained over a range of signal levels for both the Wide
Field Channel {WFC}, and the High Resolution Channel {HRC}.

FGS 9970

The Best Brown Dwarf Yet?: FGS Astrometry of the Companion to the
Hyades Eclipsing Binary V471 Tau

The analysis of over 30 yr of 161 eclipse timings of the Hyades
eclipsing binary V471 Tauri shows the presence of a low mass tertiary
companion. A third body was found from periodic variations in the
observed arrival times of the eclipses - known as the ``light time''
effect. The light time effect occurs as the relative distance {and
light travel time} changes as the eclipsing binary moves around the
barycenter of the triple system. Our analysis yields an orbital period
of P_3=30.5+/-1.6 yr, e_3=0.31+/-0.04, a semi-major axis of
a_3=11.2+/-0.4 AU, and a tertiary mass M_3 sin i_3 =0.039+/- 0.004 Mo.
For orbital inclinations 35 degrees the mass of the third body would
be below the stable hydrogen burning limit of M~0.07 Mo and thus would
be a brown dwarf. We propose HST/FGS observations of V471 Tau over the
next 3 years {2 HST orbits/year} to determine its astrometric orbit.
These HST observations, when combined with Hipparcos astrometry and
the light time orbit, will unambiguously yield the orbital inclination
and the mass of the third body. The identification of a brown dwarf in
V471 Tau will provide the first direct dynamical mass determination of
a brown dwarf with a known age {tau{Hyades}=625 Myr}, chemical
composition, and distance. In a few years {near maximum elongation},
it should be feasible to obtain IR images and spectra of this object
that will provide crucial tests of brown dwarf models.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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.

NIC3 10861

An ACS Treasury Survey of the Coma cluster of galaxies

We propose to use the unique spatial resolution of HST and ACS to
construct a Treasury imaging survey of the core and infall region of
the richest local cluster, Coma. We will observe samples of thousands
of galaxies down to magnitude B=27.3 with the aim of studying in
detail the dwarf galaxy population which, according to hierarchical
models of galaxy formation, are the earliest galaxies to form in the
universe. Our initial scientific objectives a 1} A study of the
structure of the dwarf galaxies, including scaling laws, nuclear
structure and morphology, to compare with hierarchical and
evolutionary models of their formation. 2} A study of the stellar
populations from colors and color gradients, and how the internal
chemical evolution of galaxies is affected by interaction with the
cluster gaseous and galaxy environment. 3} To determine the effect of
the cluster environment upon morphological features, disks, bulges and
bars, by comparing these structure in the Coma sample with field
galaxy samples. 4} Identification of dwarf galaxy samples for further
study with the new generation of multi-object and integral-field
spectrographs on 8-10 metre class telescopes such as Keck, Subaru,
Gemini, and GTC. This is the first such survey of a nearby rich
cluster. It will provide a key database for studies of galaxy
formation and evolution, and a very needed reference for comparison
with similar galaxy surveys both in lower density environments in the
nearby universe, and in high density environments at high redshifts.

WFPC2 10915

ACS Nearby Galaxy Survey

Existing HST observations of nearby galaxies comprise a sparse and
highly non-uniform archive, making comprehensive comparative studies
among galaxies essentially impossible. We propose to secure HST's
lasting impact on the study of nearby galaxies by undertaking a
systematic, complete, and carefully crafted imaging survey of ALL
galaxies in the Local Universe outside the Local Group. The resulting
images will allow unprecedented measurements of: {1} the star
formation history {SFH} of a 100 Mpc^3 volume of the Universe with a
time resolution of Delta[log{t}]=0.25; {2} correlations between
spatially resolved SFHs and environment; {3} the structure and
properties of thick disks and stellar halos; and {4} the color
distributions, sizes, and specific frequencies of globular and disk
clusters as a function of galaxy mass and environment. To reach these
goals, we will use a combination of wide-field tiling and pointed deep
imaging to obtain uniform data on all 72 galaxies within a
volume-limited sample extending to ~3.5 Mpc, with an extension to the
M81 group. For each galaxy, the wide-field imaging will cover out to
~1.5 times the optical radius and will reach photometric depths of at
least 2 magnitudes below the tip of the red giant branch throughout
the limits of the survey volume. One additional deep pointing per
galaxy will reach SNR~10 for red clump stars, sufficient to recover
the ancient SFH from the color-magnitude diagram. This proposal will
produce photometric information for ~100 million stars {comparable to
the number in the SDSS survey} and uniform multi-color images of half
a square degree of sky. The resulting archive will establish the
fundamental optical database for nearby galaxies, in preparation for
the shift of high-resolution imaging to the near-infrared.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10522 - GSAcq(2,3,3) takes multiple CT attempts before ultimately succeeding

OTA SE review of PTAS processing log file (M_SA317Q_1.LG2) finds that
the GSAcq(2,3,3) scheduled to start at 2006.321/07:31:10 entered CT 7
times before ultimately succeeding.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 07 07
FGS REacq 08 08
OBAD with Maneuver 32 32

SIGNIFICANT EVENTS: (None)