HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4500
PERIOD
COVERED: UT December 5, 2007 (DOY 339)
OBSERVATIONS
SCHEDULED
ACS/SBC
10907
New
Sightlines for the Study of Intergalactic Helium: A Dozen
High-Confidence,
UV-Bright Quasars from SDSS/GALEX
The
reionization of intergalactic helium is thought to have occurred
between
redshifts of about 3 and 4. Detailed study of HeII Lyman-alpha
absorption
toward a handful quasars at 2.7<z<3.3 demonstrates the great
potential
of such probes of the IGM, but the current critically-small
sample
limits confidence in resulting cosmological inferences. The
requisite
unobscured quasar sightlines to high-redshift are extremely
rare,
especially due to severe absorption in random intervening
Lyman-limit
systems, but SDSS provides thousands of z>3.1 quasars
potentially
suitable for HeII studies. We have cross-correlated SDSS
quasars
with GALEX UV sources to obtain a dozen new, very
high-confidence,
candidate quasars/sightlines {z=3.1 to 4.1} potentially
useful
for detailed HeII studies even with current HST instruments. We
propose
brief, 2-orbit per target, reconnaissance spectral exposures
with
the ACS SBC prism to definitively verify UV flux down to the HeII
break.
Our combined SDSS/GALEX selection insures a very high-yield of
confirmations,
as the quasars are already known to be UV-bright from
broadband
GALEX images. The additional sightlines, extending to very
high-redshift,
will directly enable ensemble spectral stacks, as well as
long
exposure follow-up spectra, at high S/N with the ACS/SBC
ultraviolet
prisms {or perhaps STIS or
measure
the spectrum and evolution of the ionizing background radiation,
the
evolution of HeII opacity, and the density of intergalactic baryons.
ACS/SBC
11309
Chemical
Composition of an Exo-Neptune
The
recent discovery that the
its
host star has presented us the first chance to observationally study
ice
giant formation beyond our solar system {Gillon et al. 2007}. Using
Directors
Discretionary time, we propose to obtain a high-precision
light
curve of the GJ 436 b transit with the FGS in order to improve the
current
radius determination for this planet. Measuring a precise radius
for
GJ 436 b will allow us to ascertain whether the planet has a pure
water
vapor or H/He envelope like Uranus and Neptune. Knowing this will
constrain
its formation and evolution and help place our own solar
system
ice giants in a broader context. Additionally, a precise radius
for
GJ 436 b will be a necessity for interpreting the certain follow-up
observations
of this unique system.
WFPC2
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.
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 DARKs. 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
11197
Sweeping
Away the Dust: Reliable Dark Energy with an Infrared Hubble
Diagram
We
propose building a high-z Hubble Diagram using type Ia supernovae
observed
in the infrared rest-frame J-band. The infrared has a number of
exceptional
properties. The effect of dust extinction is minimal,
reducing
a major systematic that may be biasing dark energy
measurements.
Also, recent work indicates that type Ia supernovae are
true
standard candles in the infrared meaning that our Hubble diagram
will
be resistant to possible evolution in the Phillip's relation over
cosmic
time. High signal-to-noise measurements of 16 type Ia events at
z~0.4
will be compared with an independent optical Hubble diagram from
the
ESSENCE project to test for a shift in the derived dark energy
equation
of state due to a systematic bias. In Cycle 15 we obtained
NICMOS
photometry of 8 ESSENCE supernovae and are awaiting template
observations
to place them on the IR Hubble diagram. Here we request
another
8 supernovae be studied in the final season of the ESSENCE
search.
Because of the bright sky background, H-band photometry of z~0.4
supernovae
is not feasible from the ground. Only the superb image
quality
and dark infrared sky seen by HST makes this test possible. This
experiment
may also lead to a better, more reliable way of mapping the
expansion
history of the universe with the Joint Dark Energy Mission.
NIC3
11082
NICMOS
Imaging of GOODS: Probing the Evolution of the Earliest Massive
Galaxies,
Galaxies Beyond Reionization, and the High Redshift Obscured
Universe
(uses
ACS/SBC and WFPC2)
Deep
near-infrared imaging provides the only avenue towards
understanding
a host of astrophysical problems, including: finding
galaxies
and AGN at z > 7, the evolution of the most massive galaxies,
the
triggering of star formation in dusty galaxies, and revealing
properties
of obscured AGN. As such, we propose to observe 60 selected
areas
of the GOODS North and South fields with NICMOS Camera 3 in the
F160W
band pointed at known massive M > 10^11 M_0 galaxies at z > 2
discovered
through deep Spitzer imaging. The depth we will reach {26.5
AB
at 5 sigma} in H_160 allows us to study the internal properties of
these
galaxies, including their sizes and morphologies, and to
understand
how scaling relations such as the Kormendy relationship
evolved.
Although NIC3 is out of focus and undersampled, it is currently
our
best opportunity to study these galaxies, while also sampling enough
area
to perform a general NIR survey 1/3 the size of an ACS GOODS field.
These
data will be a significant resource, invaluable for many other
science
goals, including discovering high redshift galaxies at z > 7,
the
evolution of galaxies onto the Hubble sequence, as well as examining
obscured
AGN and dusty star formation at z > 1.5. The GOODS fields are
the
natural location for HST to perform a deep NICMOS imaging program,
as
extensive data from space and ground based observatories such as
Chandra,
GALEX, Spitzer, NOAO, Keck, Subaru, VLT, JCMT, and the VLA are
currently
available for these regions. Deep high-resolution
near-infrared
observations are the one missing ingredient to this
survey,
filling in an important gap to create the deepest, largest, and
most
uniform data set for studying the faint and distant universe. The
importance
of these images will increase with time as new facilities
come
on line, most notably WFC3 and ALMA, and for the planning of future
JWST
observations.
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.
WFPC2
11122
Expanding
PNe: Distances and Hydro Models
We
propose to obtain repeat narrowband images of a sample of eighteen
planetary
nebulae {PNe} which have HST/WFPC2 archival data spanning time
baselines
of a decade. All of these targets have previous high
signal-to-noise
WFPC2/PC observations and are sufficiently nearby to
have
readily detectable expansion signatures after a few years. Our main
scientific
objectives are {a} to determine precise distances to these
PNe
based on their angular expansions, {b} to test detailed and highly
successful
hydrodynamic models that predict nebular morphologies and
expansions
for subsamples of round/elliptical and axisymmetric PNe, and
{c}
to monitor the proper motions of nebular microstructures in an
effort
to learn more about their physical nature and formation
mechanisms.
The proposed observations will result in high-precision
distances
to a healthy subsample of PNe, and from this their expansion
ages,
luminosities, CSPN properties, and masses of their ionized cores.
With
good distances and our hydro models, we will be able to determine
fundamental
parameters {such as nebular and central star masses,
luminosity,
age}. The same images allow us to monitor the changing
overall
ionization state and to search for the surprisingly
non-homologous
growth patterns to bright elliptical PNe of the same sort
seen
by Balick & Hajian {2004} in NGC 6543. Non-uniform growth is a sure
sign
of active pressure imbalances within the nebula that require
careful
hydro models to understand.
WFPC2
11128
Time
Scales Of Bulge Formation In Nearby Galaxies
Traditionally,
bulges are thought to fit well into galaxy formation
models
of hierarchical merging. However, it is now becoming well
established
that many bulges formed through internal, secular evolution
of
the disk rather than through mergers. We call these objects
pseudobulges.
Much is still unknown about pseudobulges, the most
pressing
questions being: How, exactly, do they build up their mass? How
long
does it take? And, how many exist? We are after an answer to these
questions.
If pseudobulges form and evolve over longer periods than the
time
between mergers, then a significant population of pseudobulges is
hard
to explain within current galaxy formation theories. A pseudobulge
indicates
that a galaxy has most likely not undergone a major merger
since
the formation of the disk. The ages of pseudobulges give us an
estimate
for the time scale of this quiescent evolution. We propose to
use
24 orbits of HST time to complete UBVIH imaging on a sample of 33
nearby
galaxies that we have observed with Spitzer in the mid-IR. These
data
will be used to measure spatially resolved stellar population
parameters
{mean stellar age, metallicity, and star formation history};
comparing
ages to star formation rates allows us to accurately constrain
the
time scale of pseudobulge formation. Our sample of bulges includes
both
pseudo- and classical bulges, and evenly samples barred and
unbarred
galaxies. Most of our sample is imaged, 13 have complete UBVIH
coverage;
we merely ask to complete missing observations so that we may
construct
a uniform sample for studying bulge formation. We also wish to
compare
the stellar population parameters to a variety of bulge and
global
galaxy properties including star formation rates, dynamics,
internal
bulge morphology, structure from bulge-disk decompositions, and
gas
content. Much of this data set is already or is being assembled.
This
will allow us to derive methods of pseudobulge identification that
can
be used to accurately count pseudobulges in large surveys. Aside
from
our own science goals, we will present this broad set of data to
the
community. Thus, we waive proprietary periods for all observations.
WFPC2
11178
Probing
Solar System History with Orbits, Masses, and Colors of
Transneptunian
Binaries
The
recent discovery of numerous transneptunian binaries {TNBs} opens a
window
into dynamical conditions in the protoplanetary disk where they
formed
as well as the history of subsequent events which sculpted the
outer
Solar System and emplaced them onto their present day heliocentric
orbits.
To date, at least 47 TNBs have been discovered, but only about a
dozen
have had their mutual orbits and separate colors determined,
frustrating
their use to investigate numerous important scientific
questions.
The current shortage of data especially cripples scientific
investigations
requiring statistical comparisons among the ensemble
characteristics.
We propose to obtain sufficient astrometry and
photometry
of 23 TNBs to compute their mutual orbits and system masses
and
to determine separate primary and secondary colors, roughly tripling
the
sample for which this information is known, as well as extending it
to
include systems of two near-equal size bodies. To make the most
efficient
possible use of HST, we will use a
optimally
schedule our observations.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
(None)
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
09
09
FGS
REacq
06
06
OBAD
with Maneuver
30
30
SIGNIFICANT
EVENTS: (None)