Daily Rpt #4787

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** #4787

PERIOD COVERED: 5am February 6 - 5am February 9, 2009 (DOY
******************* 037/1000z-040/1000z)

OBSERVATIONS SCHEDULED

ACS/SBC 11970

HST Observations of Titan's Escaping Atmosphere in Transit and in
Emission

We propose UV observations using the ACS/SBC of Titan's extended
escaping atmosphere for the Jan/Feb 2009 period of transits of Titan
across Saturn. A combination of absorption of Saturn's reflected solar
UV emission in transit, and extended emissions primarily from H atoms
away from transit, will yield new information about the structure of
Titan's extended upper atmosphere. These observations are expected to
provide new constraints on theoretical models for a hydrodynamic flow
of species through Titan's exobase level, resulting from the
interpretation of recent Cassini measurements at Titan.

WFPC2 11967

WFPC2 Imaging of the Lockman Hole

In order to understand galaxy evolution and constrain theoretical
models, we require both multiwavelength photometry (to robustly
determine physical parameters such as star formation rates and stellar
masses) and detailed morphological information. Galaxy morphology
encodes crucial information about galaxy formation history and the
physical processes that trigger star formation and AGN activity, and
high-resolution imaging for large samples of galaxies is currently
only obtainable with HST. The Lockman Hole has been the target of
extensive multi-wavelength observations from the X-ray to the radio,
and will be the target of the deepest wide-area blankfield thermal IR
observations with Herschel, but currently lacks comprehensive HST
imaging. We propose to obtain WFPC2 imaging of ~500 arcmin2 of the
central region of the Lockman Hole in F606W and F814W, to a depth of
V606~26.8 and I814~26. This imaging is crucial in order to
characterize the sources detected at other wavelengths.

WFPC2 11966

The Recent Star Formation History of SINGS Galaxies

The Spitzer Legacy project SINGS provided a unique view of the current
state of star formation and dust in a sample of galaxies of all Hubble
types. This multi-wavelength view allowed the team to create current
star formation diagnostics that are independent of the dust content
and increased our understanding of the dust in galaxies. Even so,
using the SINGS data alone we can only make rough estimates of the
recent star formation history of these galaxies. The lack of high
resolution observations (especially U-band and H-alpha) means that it
is impossible to estimate the ages of young clusters. In addition, the
low resolution of the Spitzer and ground-based observations means that
what appear to be individual Spitzer sources can actually be composed
of many individual clusters with varying ages. We need to know the
ages, star formation histories, and extinction of these individual
clusters to understand how these clusters form and age and thus
influence the evolution of the galaxy. In this proposal we address
this missing area of SINGS by obtaining high-resolution WFPC2 UBVI &
H-alpha observations to not only accurately locate and determine the
ages of the young stellar clusters in the actively star forming SINGS
galaxies but to also address a variety of other scientific issues.
Over 500 HST orbits and 500 hours of Spitzter observing time have been
dedicated to observations of the SINGS sample. But the HST
observations have not been systematic. By adding a relatively small
fraction of this time for these requested observations, we will
greatly enhance the legacy value of the SINGS observations by creating
a uniform high resolution multi-wavelength HST archive that matches
the quality of the lower resolution SINGS archive.

WFPC2 11962

A New Supernova in the Antennae; Narrowing in on the Hubble Constant
and Dark Energy

A measurement of the Hubble constant to a precision of a few percent
would be a powerful aid to the investigation of the nature of dark
energy and a potent "end-to-end" test of the present cosmological
model. In Cycle 15 we constructed a new, streamlined distance ladder
utilizing high-quality type Ia supernova data and observations of
Cepheids with HST in the near-IR to minimize the dominant sources of
systematic uncertainty in past measurements of the Hubble constant and
reduce its total uncertainty to a little under 5%. Here we propose to
exploit this new route with a rare opportunity to begin reducing the
remaining uncertainty. SN 2007sr in the Antennae (NGC 4038/9) is the
rare SN Ia which is suitable for increasing the precision of small
calibration sample of SNe Ia. Even rarer is that it is close enough
that it's Cepheids are within range of observing with WFPC2 (and
NICMOS, should it return to life). But we need to act fast as the
window of long visibility and fixed orient runs from mid-early
December 2008 to early March 2009. We request 34 orbits with WFPC2 to
find the Cepheids in the SN host. We also request 16 orbits to observe
the Cepheids we find with Camera 2, F160W if NICMOS becomes available
by April 2009 . (If NICMOS does not return we would forgo these
observations and ask the TTRB to let us make them with our own WFC3-IR
allocation, though we much prefer the smaller pixel size of NIC2).

WFPC2 11944

Binaries at the Extremes of the H-R Diagram

We propose to use HST/Fine Guidance Sensor 1r to survey for binaries
among some of the most massive, least massive, and oldest stars in our
part of the Galaxy. FGS allows us to spatially resolve binary systems
that are too faint to observe using ground-based, speckle or optical
long baseline interferometry, and too close to resolve with AO. We
propose a SNAP-style program of single orbit FGS TRANS mode
observations of very massive stars in the cluster NGC 3603, luminous
blue variables, nearby low mass main sequence stars, cool subdwarf
stars, and white dwarfs. These observations will help us to (1)
identify systems suitable for follow up studies for mass
determination, (2) study the role of binaries in stellar birth and in
advanced evolutionary states, (3) explore the fundamental properties
of stars near the main sequence-brown dwarf boundary, (4) understand
the role of binaries for X-ray bright systems, (5) find binaries among
ancient and nearby subdwarf stars, and (6) help calibrate the white
dwarf mass - radius relation.

FGS 11788

The Architecture of Exoplanetary Systems

Are all planetary systems coplanar? Concordance cosmogony makes that
prediction. It is, however, a prediction of extrasolar planetary
system architecture as yet untested by direct observation for main
sequence stars other than the Sun. To provide such a test, we propose
to carry out FGS astrometric studies on four stars hosting seven
companions. Our understanding of the planet formation process will
grow as we match not only system architecture, but formed planet mass
and true distance from the primary with host star characteristics for
a wide variety of host stars and exoplanet masses.

We propose that a series of FGS astrometric observations with
demonstrated 1 millisecond of arc per-observation precision can
establish the degree of coplanarity and component true masses for four
extrasolar systems: HD 202206 (brown dwarf+planet); HD 128311
(planet+planet), HD 160691 = mu Arae (planet+planet), and HD 222404AB
= gamma Cephei (planet+star). In each case the companion is identified
as such by assuming that the minimum mass is the actual mass. For the
last target, a known stellar binary system, the companion orbit is
stable only if coplanar with the AB binary orbit.

ACS/SBC 11579

The Difference Between Neutral- and Ionized-Gas Metal Abundances in
Local Star-Forming Galaxies with COS

The metallicity of galaxies and its evolution with redshift is of
paramount importance for understanding galaxy formation. Abundances in
the interstellar medium (ISM) are typically determined using
emission-line spectroscopy of HII regions. However, since HII regions
are associated with recent SF they may not have abundances typical for
the galaxy as a whole. This is true in particular for star-forming
galaxies (SFGs), in which the bulk of the metals may be contained in
the neutral gas. It is therefore important to directly probe the metal
abundances in the neutral gas. This can be done using absorption lines
in the Far UV. We have developed techniques to do this in SFGs, where
the absorption is measured for sightlines toward bright SF regions
within the galaxy itself. We have successfully applied this technique
to a sample of galaxies observed with FUSE. The results have been very
promising, suggesting in I Zw 18 that abundances in the neutral gas
may be up to 0.5 dex lower than in the ionized gas. However, the
interpretation of the FUSE data is complicated by the very large FUSE
aperture (30 arcsec), the modest S/N, and the limited selection of
species available in the FUSE bandpass. The advent of COS on HST now
allows a significant advance in all of these areas. We will therefore
obtain absorption line spectroscopy with G130M in the same sample for
which we already have crude constraints from FUSE. We will obtain
ACS/SBC images to select the few optimal sightlines to target in each
galaxy. The results will be interpreted through line-profile fitting
to determine the metal abundances constrained by the available lines.
The results will provide important new insights into the metallicities
of galaxies, and into outstanding problems at high redshift such as
the observed offset between the metallicities of Lyman Break Galaxies
and Damped Lyman Alpha systems.

ACS/SBC 11566

Imaging Saturn's Equinoctal Auroras

Auroral emissions provide an indispensable diagnostic tool for the
energetic processes occurring in planetary magnetospheres. In 2009
Saturn will reach equinox for the first time since the advent of
high-sensitivity planetary ultraviolet (UV) auroral imaging, offering
a unique, transient opportunity to observe both polar auroral regions
simultaneously. The observations proposed here will not only provide
the best images to date of Saturn's northern auroras, they will
address three fundamental issues: (1) Are Saturn's auroras similar in
the north and south? This will reveal the nature of the processes that
cause the northern auroras, and verify the multipole nature of
Saturn's internal magnetic field. (2) Is the location of the northern
auroral emission symmetric with to the south? This will indicate why
the southern auroral oval is displaced a few degrees toward midnight
from the spin pole. It will also reveal whether the oscillation
observed in the location of the southern auroral oval is similarly
observed in the north, illuminating the nature of near-planetary
period oscillations observed throughout the magnetosphere and
potentially providing a value for the elusive rotation period of the
deep interior. (3) What is the influence of equinox on the
magnetosphere? The unique orientation of the planetary spin axis at
equinox will reveal whether the auroras are influenced by the
direction of the interplanetary magnetic field, and whether the Sun's
effect on Saturn's magnetosphere changes throughout the planet's
seasons. The Hubble Space Telescope is the only instrument capable of
providing global instantaneous coverage of Saturn's UV auroras, and
since Saturn's orbital period is ~30 years, Cycle 17 is the only
opportunity to make these observations.

WFPC2 11113

Binaries in the Kuiper Belt: Probes of Solar System Formation and
Evolution

The discovery of binaries in the Kuiper Belt and related small body
populations is powering a revolutionary step forward in the study of
this remote region. Three quarters of the known binaries in the Kuiper
Belt have been discovered with HST, most by our snapshot surveys. The
statistics derived from this work are beginning to yield surprising
and unexpected results. We have found a strong concentration of
binaries among low-inclination Classicals, a possible size cutoff to
binaries among the Centaurs, an apparent preference for nearly equal
mass binaries, and a strong increase in the number of binaries at
small separations. We propose to continue this successful program in
Cycle 16; we expect to discover at least 13 new binary systems,
targeted to subgroups where these discoveries can have the greatest
impact.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11664 - Loss of Lock @ 037/11:08:53z

Following a successful REAcq(1,2,1) at 037/10:50:58z, loss of lock was
observed at 11:08:03 with QF1STOPF, QF2STOPF and QSTOP flags set and
take data flag down. Eight ACS #779 status buffer messages (Fold
Mechanism Move while Take Data Flag is down) were received. A type 3
slew was in progress.

Observations possibly affected: ACS #12-13, Proposal ID#11970

11666 - REAcq(1,2,2) at 040/04:57:07z failed due to STOP Flag on FGS1
at 04:59:47z.

Observations affected: WFPC2 #8-9, Proposal ID#11966

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

************************* SCHEDULED***** SUCCESSFUL***** FAILURE
TIMES

FGS GSacq*************** 20************* 20
FGS REacq*************** 20************* 19
OBAD with Maneuver ***** 80************* 80
LOSS of LOCK*********************************************
037/11:08:53z

SIGNIFICANT EVENTS: (None)