Notice: For the foreseeable future, the daily reports may
contain
apparent discrepancies between some proposal descriptions
and the listed
instrument usage. This is due to the conversion of
previously approved
ACS WFC or HRC observations into WFPC2, or NICMOS
observations
subsequent to the loss of ACS CCD science capability in
late January.
HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4388
PERIOD COVERED: UT June 20, 2007 (DOY 171)
OBSERVATIONS SCHEDULED
WFPC2 10922
Searching for Signs of a Double Generation of Stars in
Galactic Globular
Clusters
This proposal has been stimulated by new findings of ours
that may have
a strong impact on the interpretation of globular cluster
{GC} stellar
populations. In 2004, based on HST data, we have found
that the main
sequence of the Galactic globular cluster Omega Centauri
is split into
two sequences; spectroscopic analysis has shown that the
only isochrones
which are able to fit the combination of color and
metallicity of the
bluest of the two sequences were younger and greatly
enriched in helium.
A number of observational facts, and theoretical evidence
suggest that
our results on Omega Centauri might represent an extreme
case of a
phenomenon which has also been at work in other GCs. We
have selected
the most promising GCs to find out whether this hypothesis
is correct,
and make a strong case for its likelihood and the value of
pursuing it.
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 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
images. Each observation will need its own CRMAP, as
different SAA
passages leave different imprints on the NICMOS detectors.
NIC2 10893
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 tha 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 Phillips relation
over cosmic
time. High signal-to-noise measurements of 9 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. 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
NIC3 10504
Characterizing the Sources Responsible for Cosmic
Reionization
Our group has demonstrated the role that massive clusters,
acting as
powerful cosmic lenses, can play in constraining the
abundance and
properties of low-luminosity star- forming sources beyond
z~6; such
sources are thought to be responsible for ending cosmic
reionization.
The large magnification possible in the critical regions
of well-
constrained clusters brings sources into view that lie at
or beyond the
limits of conventional exposures such as the UDF, as well
as those in
imaging surveys being undertaken with IRAC onboard
Spitzer. We have
shown that the combination of HST and Spitzer is
particularly effective
in delivering the physical properties of these distant
sources,
constraining their mass, age and past star formation
history.
Indirectly, we therefore gain a valuable glimpse to yet
earlier epochs.
Recognizing the result {and limitations} of the UDF
exposure, we propose
a systematic search through 6 lensing clusters with ACS
and NICMOS for
further z~6-7 sources in conjunction with existing deep
IRAC data. Our
survey will mitigate cosmic variance and extend the search
both to lower
luminosities and, by virtue of the NICMOS/IRAC combination,
to higher
redshift. The goal is to count and characterize
representative sources
at z~6-10 and to delineate the redshift range of activity
for the
planning of future 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.
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:
18104-0 - MSS/CSS Initialization Test#39 for day 171
18107-0 - TDRSS Orbital Elements Update @171/1208z
18054-0 - Preview KF Sun Vector Data via Telemetry Diags
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq 06
06
FGS REacq
08
08
OBAD with Maneuver
28
28
SIGNIFICANT EVENTS:
Evaluation of Universal Kalman Filter performance continued.
Details follow.
The KF was halted at 161/17:27. It was reinitialized with
the MSS and
CSS sensor inputs enabled at 171/17:30 (OR 18104-0). All
UKF parameters
showed nominal operation. The test was to monitor the
convergence of the
filter after restart with the MSS and CSS sensor inputs
enabled during a
vehicle maneuver and during a fast changing B-field
(M_C_IVF, Test #5).
The filter will remain in the MSS/CSS configuration until
tomorrow when
additional convergence testing is executed.