HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4566
PERIOD
COVERED: UT March 12, 2008 (DOY 072)
OBSERVATIONS
SCHEDULED
NIC1/NIC2/NIC3
8795
NICMOS Post-SAA calibration - CR Persistence Part 6
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 i
mages.
Each observation will need its own CRMAP, as different SAA
passages
leave different imprints on the NICMOS detectors.
NIC2
11142
Revealing
the Physical Nature of Infrared Luminous Galaxies at 0.3
We
aim to determine physical properties of IR luminous galaxies at
0.3<z<2.7
by requesting coordinated HST/NIC2 and MIPS 70um observations
of
a unique, 24um flux-limited sample with complete Spitzer mid-IR
spectroscopy.
The 150 sources investigated in this program have S{24um}
>
0.8mJy and their mid-IR spectra have already provided the majority
targets
with spectroscopic redshifts {0.3<z<2.7}. The proposed
150~orbits
of NIC2 and 66~hours of MIPS 70um will provide the physical
measurements
of the light distribution at the rest-frame ~8000A and
better
estimates of the bolometric luminosity. Combining these
parameters
together with the rich suite of spectral diagnostics from the
mid-IR
spectra, we will {1} measure how common mergers are among LIRGs
and
ULIRGs at 0.3<z<2.7, and establish if major mergers are the drivers
of
z>1 ULIRGs, as in the local Universe. {2} study the co-evolution of
star
formation and blackhole accretion by investigating the relations
between
the fraction of starburst/AGN measured from mid-IR spectra vs.
HST
morphologies, L{bol} and z. {3} obtain the current best estimates of
the
far-IR emission, thus L{bol} for this sample, and establish if the
relative
contribution of mid-to-far IR dust emission is correlated with
morphology
{resolved vs. unresolved}.
NIC3
11149
Characterizing
the Stellar Populations in Lyman-Alpha Emitters and Lyman
Break
Galaxies at 5.7<z<7 in the Subaru Deep Field
The
epoch of reionization marks a major phase transition of the
Universe,
during which the intergalactic space became transparent to UV
photons.
Determining when this occurred and the physical processes
involved
represents the latest frontier in observational cosmology. Over
the
last few years, searches have intensified to identify the population
of
high-redshift (z>6) galaxies that might be responsible for this
process,
but the progress is hampered partly by the difficulty of
obtaining
physical information (stellar mass, age, star formation
rate/history)
for individual sources. This is because the number of z>6
galaxies
that have both secure spectroscopic redshifts and high-quality
infrared
photometry (especially with Spitzer/IRAC) is still fairly
small.
Considering that only several photometric points are available
per
source, and that many model SEDs are highly degenerate, it is
crucial
to obtain as many observational constraints as possible for each
source
to ensure the validity of SED modeling. To better understand the
physical
properties of high-redshift galaxies, we propose here to
conduct
HST/NICMOS (72 orbits) and Spitzer/IRAC (102 hours) imaging of
spectroscopically
confirmed, bright (z<26 mag (AB)) Ly-alpha emitters
(LAEs)
and Lyman-break galaxies (LBGs) at 5.7<z<7 selected from the
Subaru
Deep Field. Spectroscopic redshifts remove one critical free
parameter
from SED modeling while bright source magnitudes ensure
high-quality
photometric data. By making accurate determinations of
stellar
masses, ages, and star-formation histories, we will specifically
address
the following major questions: (1) Do LAEs and LBGs represent
physically
different galaxy populations at z>6 as suggested recently?
(2)
Is Ly-alpha emission systematically suppressed at z>6 with respect
to
continuum emission? (i.e., are we reaching the epoch of incomplete
reionization?),
and (3) Do we see any sign of abnormally young stellar
population
in any of the z>6 galaxies?
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.
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.
WFPC2/NIC3
11144
Building
on the Significant NICMOS Investment in GOODS: A Bright,
Wide-Area
Search for z>=7 Galaxies
One
of the most exciting frontiers in observational cosmology has been
to
trace the buildup and evolution of galaxies from very early times.
While
hierarchical theory teaches us that the star formation rate in
galaxies
likely starts out small and builds up gradually, only recently
has
it been possible to see evidence for this observationally through
the
evolution of the LF from z~6 to z~3. Establishing that this build up
occurs
from even earlier times {z~7-8} has been difficult, however, due
to
the small size of current high-redshift z~7-8 samples -- now
numbering
in the range of ~4-10 sources. Expanding the size of these
samples
is absolutely essential, if we are to push current studies of
galaxy
buildup back to even earlier times. Fortunately, we should soon
be
able to do so, thanks to ~50 arcmin**2 of deep {26.9 AB mag at 5
sigma}
NICMOS 1.6 micron data that will be available over the two ACS
GOODS
fields as a result of one recent 180- orbit ACS backup program and
a
smaller program. These data will nearly triple the deep near-IR
imaging
currently available and represent a significant resource for
finding
and characterizing the brightest high-redshift sources -- since
high-redshift
candidates can be easily identified in these data from
their
red z-H colours. Unfortunately, the red z-H colours of these
candidates
are not sufficient to determine that these sources are at
z>=7,
and it is important also to have deep photometry at 1.1 microns.
To
obtain this crucial information, we propose to follow up each of
these
z-H dropouts with NICMOS at 1.1 microns to determine which are at
high
redshift and thus significantly expand our sample of luminous, z>=7
galaxies.
Since preliminary studies indicate that these candidates occur
in
only 30% of the NIC3 fields, our follow-up strategy is ~3 times as
efficient
as without this preselection and 9 times as efficient as a
search
in a field with no pre-existing data. In total, we expect to
identify
~8 luminous z-dropouts and possibly ~2 z~10 J-dropouts as a
result
of this program, more than tripling the number currently known.
The
increased sample sizes are important if we are to solidify current
conclusions
about galaxy buildup and the evolution of the LF from z~8.
In
addition to the high redshift science, these deep 1.1 micron data
would
have significant value for many diverse endeavors, including {1}
improving
our constraints on the stellar mass density at z~7-10 and {2}
doubling
the number of galaxies at z~6 for which we can estimate dust
obscuration.
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
05
05
FGS
REacq
10
10
OBAD
with Maneuver
30
30
SIGNIFICANT
EVENTS: (None)