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 are: 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)