HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4528
PERIOD
COVERED: UT January 016, 2008 (DOY 016)
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.
NIC3
11107
Imaging
of Local Lyman Break Galaxy Analogs: New Clues to Galaxy
Formation
in the Early Universe
We have
used the ultraviolet all-sky imaging survey currently being
conducted
by the Galaxy Evolution Explorer {GALEX} to identify for the
first
time a rare population of low-redshift starbursts with properties
remarkably
similar to high-redshift Lyman Break Galaxies {LBGs}. These
"compact
UV luminous galaxies" {UVLGs} resemble LBGs in terms of size,
SFR,
surface brightness, mass, metallicity, kinematics, dust, and color.
The
UVLG sample offers the unique opportunity of investigating some very
important
properties of LBGs that have remained virtually inaccessible
at
high redshift: their morphology and the mechanism that drives their
star
formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS
in
order to 1} characterize their morphology and look for signs of
interactions
and mergers, and 2} probe their star formation histories
over
a variety of timescales. The images show a striking trend of small-
scale
mergers turning large amounts of gas into vigorous starbursts {a
process
referred to as dissipational or "wet" merging}. Here, we propose
to
complete our sample of 31 LBG analogs using the ACS/SBC F150LP {FUV}
and
WFPC2 F606W {R} filters in order to create a statistical sample to
study
the mechanism that triggers star formation in UVLGs and its
implications
for the nature of LBGs. Specifically, we will 1} study the
trend
between galaxy merging and SFR in UVLGs, 2} artificially redshift
the
FUV images to z=1-4 and compare morphologies with those in similarly
sized
samples of LBGs at the same rest-frame wavelengths in e.g. GOODS,
UDF,
and COSMOS, 3} determine the presence and morphology of significant
stellar
mass in "pre- burst" stars, and 4} study their immediate
environment.
Together with our Spitzer {IRAC+MIPS}, GALEX, SDSS and
radio
data, the HST observations will form a unique union of data that
may
for the first time shed light on how the earliest major episodes of
star
formation in high redshift galaxies came about. This proposal was
adapted
from an ACS HRC+WFC proposal to meet the new Cycle 16 observing
constraints,
and can be carried out using the ACS/SBC and WFPC2 without
compromising
our original science goals.
WFPC2
11125
The
Dynamical Evolution of Globular Clusters
Globular
clusters evolve through dynamical interactions, with primordial
binaries
extending the time until core collapse by up to an order of
magnitude,
depending on the initial binary fraction. These dynamical
interactions
plus mass segregation causes the binary fraction to rise in
the
core but fall at larger radii. We hope to eventually test these
broad
predictions by comparing them to the binary properties for
globular
clusters at different states of evolution, defined by the ratio
of
their age to the dynamical relaxation time at the half-light radius.
The
most important unknown aspects in the modeling process are the
initial
conditions of binaries in the cluster. Here we propose to
determine
the initial binary fraction as a function of radius by
studying
three of the dynamically youngest globular clusters {NGC 5053,
NGC
5466, and NGC 5897}. The presence of binaries thickens the
Sequence
in a color-magnitude diagram, which can be detected with deep
multicolor
images.
WFPC2/NIC3/ACS/SBC
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:
OR #18172-1
– Clear ACS SBC Event Flag #2 for OBS #11162
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
07
07
FGS
REacq
06
06
OBAD
with Maneuver
18
18
SIGNIFICANT
EVENTS: (None)