Daily Report #4777

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** #4777

PERIOD COVERED: 5am January 23 - 5am January 26, 2009 (DOY
*************************** 023/1000z-026/1000z)

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 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.

FGS 11964

Post FGS1r AMA-Adjustment: OFAD Check and Alignment Calibration, 2008

The FGS1 AMA optimization proposal (11963) leaves the AMA mirror in a
new position, which shifts the FGS1r FOV relative to FGS2r and FGS3
and has the potential to change the FGS1r OFAD solution. This proposal
will use the astrometric open cluster NGC 5617 to check for 1 mas size
changes in the OFAD and to establish the new alignment of FGS1r
relative to FGS2r and FGS3 to a precision of approximately 25 mas. The
OFAD check requires 4 HST orbits before, and 4 HST orbits after, the
AMA adjustment. Each orbit observes the same stars in NGC 5617 with
FGS1r in POS mode. The alignment aspect of this proposal uses data
from these same orbits. The ICRS positions of the relevant stars are
taken from the UCAC catalog, but the proper motions taken from the
"special guide star plate ZZZT" provided by Yale University. We chose
guide stars in FGS2r and FGS3, and astrometry targets that are common
to GSC2, UCAC, and ZZZT. Each visit uses a unique guide star pair, so
that all the visits taken together have guide stars spanning the
guider FGSs FOV.


FGS 11943/11944

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 for 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.

WFPC2 11612

Eta Carinae's Continuing Instability and Recovery - the 2009 Event

Eta Carinae is the only really observable example of structural
recovery from a massive giant eruption, a "supernova imposter' event.
Moreover it is the only well-observed star above 100 Msun, and its
5.5-year-recurrent spectroscopic events provide extraordinary clues to
its surface instability. This truly unique combination of attributes
makes it valuable for understanding the most massive stars. A fresh
development arose a few years ago: The star has brightened much faster
than before, and appears to have entered a rapid stage in its
post-eruption recovery.

A spectroscopic event will occur at 2009.0, soon after the planned HST
servicing mission. Because of the recent secular trend, this event is
expected to differ from its well-observed 2003.5 predecessor. The
differences will be very important, because they offer clues to
very-massive-star structural instabilities that can't be observed in
any other known way.

Some of the needed observations require HST's high spatial resolution
and UV coverage. We propose an efficient, well-chosen set of STIS and
ACS observations around the critical time. If the servicing mission is
too late for the event, then a subset of the observations will still
be merited.

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 11289

SL2S: The Strong Lensing Legacy Survey

Recent systematic surveys of strong galaxy-galaxy lenses {CLASS,
SLACS, GOODS, etc.} are producing spectacular results for galaxy
masses roughly below a transition mass M~10^13 Mo. The observed lens
properties and their evolution up to z~0.2, consistent with numerical
simulations, can be described by isothermal elliptical potentials. In
contrast, modeling of giant arcs in X-ray luminous clusters {halo
masses M ~10^13 Mo} favors NFW mass profiles, suggesting that dark
matter halos are not significantly affected by baryon cooling. Until
recently, lensing surveys were neither deep nor extended enough to
probe the intermediate mass density regime, which is fundamental for
understanding the assembly of structures. The CFHT Legacy Survey now
covers 125 square degrees, and thus offers a large reservoir of strong
lenses probing a large range of mass densities up to z~1. We have
extracted a list of 150 strong lenses using the most recent CFHTLS
data release via automated procedures. Following our first SNAPSHOT
proposal in cycle 15, we propose to continue the Hubble follow-up
targeting a larger list of 130 lensing candidates. These are
intermediate mass range candidates {between galaxies and clusters}
that are selected in the redshift range of 0.2-1 with no a priori
X-ray selection. The HST resolution is necessary for confirming the
lensing candidates, accurate modeling of the lenses, and probing the
total mass concentration in galaxy groups up to z~1 with the largest
unbiased sample available to date.

WFPC2 11103

A Snapshot Survey of The Most Massive Clusters of Galaxies

We propose the continuation of our highly successful SNAPshot survey
of a sample of 125 very X-ray luminous clusters in the redshift range
0.3-0.7. As demonstrated by the 25 snapshots obtained so far in
Cycle14 and Cycle15 these systems frequently exhibit strong
gravitational lensing as well as spectacular examples of violent
galaxy interactions. The proposed observations will provide important
constraints on the cluster mass distributions, the physical nature of
galaxy-galaxy and galaxy-gas interactions in cluster cores, and a set
of optically bright, lensed galaxies for further 8-10m spectroscopy.
All of our primary science goals require only the detection and
characterization of high-surface-brightness features and are thus
achievable even at the reduced sensitivity of WFPC2. Because of their
high redshift and thus compact angular scale our target clusters are
less adversely affected by the smaller field of view of WFPC2 than
more nearby systems. Acknowledging the broad community interest in
this sample we waive our data rights for these observations.

WFPC2 10877

A Snapshot Survey of the Sites of Recent, Nearby Supernovae

During the past few years, robotic {or nearly robotic} searches for
supernovae {SNe}, most notably our Lick Observatory Supernova Search
{LOSS}, have found hundreds of SNe, many of them in quite nearby
galaxies {cz 4000 km/s}. Most of the objects were discovered before
maximum brightness, and have follow-up photometry and spectroscopy;
they include some of the best-studied SNe to date. We propose to
conduct a snapshot imaging survey of the sites of some of these nearby
objects, to obtain late-time photometry that {through the shape of the
light and color curves} will help reveal the origin of their lingering
energy. The images will also provide high-resolution information on
the local environments of SNe that are far superior to what we can
procure from the ground. For example, we will obtain color-color and
color-magnitude diagrams of stars in these SN sites, to determine the
SN progenitor masses and constraints on the reddening. Recovery of the
SNe in the new HST images will also allow us to actually pinpoint
their progenitor stars in cases where pre- explosion images exist in
the HST archive. This proposal is an extension of our successful Cycle
13 snapshot survey with ACS. It is complementary to our Cycle 15
archival proposal, which is a continuation of our long-standing
program to use existing HST images to glean information about SN
environments.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11644 - At 023/21:06:13 GSAcq (2,3,2) scheduled from 023/21:03:13 -
21:10:28 failed to RGA Hold due to QF2STOPF and QSTOP flags on FGS-2.

Observation affected: Astrometry Proposal 11944

11645 - GSacq(1,2,2) at 025/03:41:59z failed to RGA control with
Search Radius Limit exceeded on FGS 1.

Observations affected:* WFPC #199-202 Proposal #11103.

11646 - GSacq(2,3,3) at 025/05:27:34z failed to RGA control with
Search Radius Limit exceeded on FGS 2 at 025/05:32:25z.

Observations affected:* Astrometry Proposal #11944.

11647 - GSacq(1,2,2) at 025/12:46:18 failed to RGA control at 12:51:13
with QF1STOPF and QSTOP flags set.

Observations affected: WFPC 203 to 206, proposal 10877.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

************************ SCHEDULED***** SUCCESSFUL

FGS GSacq*************** 24***************** 20
FGS REacq*************** 13***************** 13
OBAD with Maneuver ***** 74***************** 74

SIGNIFICANT EVENTS: (None)