HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4798
PERIOD COVERED: 5am February 24 - 5am February 25, 2009
(DOY
055/1000z-056/1000z)
OBSERVATIONS SCHEDULED
ACS/SBC 11980
Deep FUV Imaging of Cooling Flow Clusters
We propose to take deep ACS FUV images of a carefully
selected sample of
19 bright central galaxies in nearby galaxy clusters. This
program is
the last critical element of a comprehensive investigation
of the impact
of stellar and AGN feedback on the local galaxy cluster
environment. The
HST images will complement new, high-resolution, Halpha
images obtained
with the recently commissioned Maryland-Magellan Tunable
Filter (MMTF)
on the Baade 6.5m telescope, archival Chandra, VLA, and
GALEX data, and
on-going H2/NIR observations. The MMTF data have revealed
unsuspected
filamentary complexes in several systems. The GALEX data
often show
hints of extended NUV and FUV emission on a similar scale,
but their
poor spatial resolution prevents meaningful comparison
with the MMTF
data. The HST data will provide this much needed gain in
resolution. The
combined radio-H2-Halpha-FUV-X-ray dataset will allow us
to derive with
unprecedented precision the role of the AGN, hot stars,
shocks, and
relativistic particles on the excitation and
thermodynamics of the
multi-phase intracluster and interstellar media in these
systems. This
is an important question since the formation and evolution
of most
cluster galaxies have likely been affected by these
processes.
ACS/SBC 11982
Spanning the Reionization History of IGM Helium: a Large
and Efficient
HST Spectral Survey of Far-UV-Bright Quasars
The reionization of IGM helium is thought to have occurred
at redshifts
of z=3 to 4. Detailed studies of HeII Lyman-alpha
absorption toward a
handful of QSOs at 2.7<z<3.3 demonstrated the high
potential of such IGM
probes, but the small sample size and redshift range limit
confidence in
cosmological inferences. The requisite unobscured
sightlines to high-z
are extremely rare, but we've cross-correlated 10, 000
z>2.8 SDSS DR7
(and other) quasars with GALEX GR4 UV sources to obtain
550 new, high
confidence, sightlines potentially useful for HST HeII
studies; and in
cycle 15-16 trials we demonstrated the efficacy of our
SDSS/GALEX
selection approach identifying 9 new HeII quasars at
unprecedented 67%
efficiency. We propose the first far-UV-bright HeII quasar
survey that
is both large in scale and also efficient, via 2-orbit
reconnaissance
ACS/SBC prism spectra toward a highly select subset of 40
new SDSS/GALEX
quasars at 3.1<z<5.1. These will provide a community
resource list that
includes 5 far-UV-bright (restframe) HeII sightlines in
each of 8
redshift bins spanning 3.1<z<3.9 (and perhaps
several objects at z>4),
enabling superb post-SM4 follow-up spectra with COS or
STIS. But
simultaneously and independent of any SM4 uncertainties,
we will hereby
directly obtain 10-orbit UV spectral stacks from the 5
HeII quasars in
each of the 8 redshift bins to trace the reionization
history of IGM
helium over at least
3.1<z<3.9. These spectral stacks will average over
cosmic variance and individual object pathology. Our new
high-yield HeII
sightline sample and spectral stacks, covering a large
redshift range,
will allow confident conclusions about the spectrum and
evolution of the
ionizing background, the evolution of HeII opacity, the
density of IGM
baryons, and the epoch of helium reionization.
FGS 11943 / WFPC2 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.
WFPC2 11302
WFPC2 CYCLE 16 Standard Darks - Part III
This dark calibration program obtains dark frames every
week in order to
provide data for the ongoing calibration of the CCD dark
current rate,
and to monitor and characterize the evolution of hot
pixels. Over an
extended period these data will also provide a monitor of
radiation
damage to the CCDs.
WFPC2 11956
Hubble Heritage: Side B
We propose a program of 39 orbits to observe 6 targets
with WFPC2
following a successful return to science using side B
electronics. These
observations will be used for Hubble Heritage releases in
the months
leading up to servicing mission 4. Because of launch
delays, our reserve
of releasable images is growing dangerously slim. We are
proposing here
to replenish one of our important lines of communication
with the
public.
We have carefully chosen targets that can efficiently use
single
pointings of WFPC2 to obtain images of visually striking
and
astrophysically interesting targets. Observations will
reach high S/N
and will be dithered and subsampled to improve the
resolution and pixel
scale to near ACS/WFC3 quality at a modest cost in
exposure time. Most
of the observations will schedule in the interim between a
return to
science and the availability of new science proposals that
may be
selected in response to an interim call for proposals.
WFPC2 11986
Completing HST's Local Volume Legacy
Nearby galaxies offer one of the few laboratories within
which stellar
populations can be tied to multi-wavelength observations.
They are thus
essential for calibrating and interpreting key
astrophysical
observables, such as broad-band luminosities, durations
and energy input
from starbursts, and timescales of UV, H-alpha, and FIR
emission. The
study of stellar populations in nearby galaxies requires
high-resolution
observations with HST, but HST's legacy for this limited
set of galaxies
remains incomplete.
As a first attempt to establish this legacy, The ACS
Nearby Galaxy
Survey Treasury (ANGST) began observations in late 2006.
ANGST was
designed to carry out a uniform multi-color survey of a
volume-limited
sample of ~70 nearby galaxies that could be used for
systematic studies
of resolved stellar populations. The resulting data
provide nuanced
constraints on the processes which govern star formation
and galaxy
evolution, for a well-defined population of galaxies. All
photometry for
the survey has been publicly released.
However, the failure of ACS 4.5 months after ANGST began
taking data led
to a drastic reduction in the planned survey. The loss is
two-fold.
First, the goals of completeness and uniformity were
greatly
compromised, impacting global comparison studies. Second,
the variety of
observed star formation histories was reduced. Given that
we have never
found two galaxies with identical star formation
histories, and fully
sampling the population allows us to catch those few
systems whose star
formation rates and metallicities place the strongest
constraints on key
astrophysical processes.
Here we propose WFPC2 observations of all remaining
galaxies within the
Local Volume (D<3.5Mpc) for which current HST
observations are
insufficient for meaningful stellar population studies. We
will use
these observations for research on the star formation
histories of
individual galaxies and the Local Volume, detailed
calibrations of star
formation rate indicators, and the durations of
starbursts. We will also
make them publicly available through the ANGST archive to
support future
research. The proposed observations will finally complete
a lasting
legacy of HST
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
08
08
FGS
REAcq
06
06
OBAD with Maneuver
26
26
SIGNIFICANT EVENTS: (None)