HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4846
PERIOD COVERED: 5am May 01 - 5am May 04, 2009 (DOY
121/0900z-124/0900z)
OBSERVATIONS SCHEDULED
WFPC2 11988
Searching for Intermediate Mass Black Holes in Globular
Clusters via
Proper Motions
The unambiguous detection of an intermediate mas black
hole (IMBH) in a
globular star cluster would be a major achievement for the
Hubble Space
Telescope. It is critical to know whether or not IMBHs
exist in the
centers of clusters in order to understand the dynamical
evolution of
dense stellar systems. Also, n IMBH detection would prove
the existence
of BHs in an entirely new mass range. Observationally, the
search has
been hampered by the low number of stars with known
velocities in the
central few arcseconds. This limits measurements of the
stellar velocity
dispersion in the region where the gravitational influence
of any IMBH
would be felt. Existing IMBH claims in the literature have
all been
called into question, and have all been based on
line-of-sight
velocities from spectroscopy. In cycle 13, we obtained
ACS/HRC
observations for 5 nearby Galactic globular clusters for a
new proper
motion study. Here, we request WFPC2/PC observations of
these clusters,
all of which are observable in Feb-May 2009. This 4 year
baseline will
allow us to measure the proper motions of stars into the
very center of
each cluster, and either detect or place firm constraints
on the
presence of an IMBH. In addition, we will determine
whether or not the
clusters rotate or show any anisotropy in their motions.
Our small (<75
orbit) program meets the criteria of addressing high
impact science
(IMBH detection) using innovative methods (proper
motions).
WFPC2 11987
The Recent Star Formation History of SINGS Galaxies
The Spitzer Legacy project SINGS provided a unique view of
the current
state of star formation and dust in a sample of galaxies
of all Hubble
types. This multi-wavelength view allowed the team to
create current
star formation diagnostics that are independent of the
dust content and
increased our understanding of the dust in galaxies. Even
so, using the
SINGS data alone we can only make rough estimates of the
recent star
formation history of these galaxies. The lack of U-band
observations
means that it is impossible to estimate the ages of young
clusters. In
addition, the low resolution of the Spitzer and
ground-based
observations means that what appear to be individual Spitzer
sources can
actually be composed of many individual clusters with
varying ages. In
this proposal we plan to address this missing area in
SINGS by obtaining
high-resolution WFPC2 UBVI observations to accurately find
and determine
the ages of the young stellar clusters in a subset of the
SINGS
galaxies. These observations will greatly enhance the
legacy value of
the SINGS observations while also directly answering
questions
pertaining to star formation in galaxies.
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.
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.
WFPC2 11975
UV Light from Old Stellar Populations: a Census of UV
Sources in
Galactic Globular Clusters
In spite of the fact that HST has been the only operative
high-resolution eye in the UV-window over the last 18
years, no
homogeneous UV survey of Galactic globular clusters (GGCs)
has been
performed to date. In order to fill this gap in the
stellar population
studies, we propose a program that exploits the unique
capability of the
WFPC2 and the SBC in the far-/mid- UV for securing deep UV
imaging of 46
GGCs. The proposed observations will allow to study with
unprecedented
accuracy the hottest GGC stars, comprising the extreme
horizontal branch
(HB) stars and their progeny (the so-called AGB-manque',
and Post-early
AGB stars), and "exotic stellar populations"
like the blue straggler
stars and the interacting binaries. The targets have been
selected to
properly sample the GGC metallicity/structural parameter
space, thus to
unveil any possible correlation between the properties of
the hot
stellar populations and the cluster characteristics. In
addition, most
of the targets have extended HB "blue tails",
that can be properly
studied only by means of deep UV observations, especially
in the far-UV
filters like the F160BW, that is not foreseen on the WFC3.
This data
base is complemented with GALEX observations in the
cluster outermost
regions, thus allowing to investigate any possible trend
of the
UV-bright stellar types over the entire radial extension
of the
clusters. Although the hottest GGC stars are just a small
class of
"special" objects, their study has a broad
relevance in the context of
structure formation and chemical evolution in the early
Universe,
bringing precious information on the basic star formation
processes and
the origin of blue light from galaxies. Indeed, the
proposed
observations will provide the community with an
unprecedented data set
suitable for addressing a number of still open
astrophysical questions,
ranging from the main drivers of the HB morphology and the
mass loss
processes, to the origin of the UV upturn in elliptical
galaxies, the
dating of distant systems from integrated light, and the
complex
interplay between stellar evolution and dynamics in dense
stellar
aggregates. In the spirit of constructing a community
resource, we
entirely waive the proprietary period for these
observations.
FGS 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 to observe using 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 11794
Cycle 16 Visible Earth Flats
This proposal monitors flatfield stability. This proposal
obtains
sequences of Earth streak flats to construct high quality
flat fields
for the WFPC2 filter set. These flat fields will allow
mapping of the
OTA illumination pattern and will be used in conjunction
with previous
internal and external flats to generate new pipeline
superflats. These
Earth flats will complement the Earth flat data obtained
during cycles
4-15.
WFPC2 11793
WFPC2 Cycle 16 Internal Monitor
This calibration proposal is the Cycle 15 routine internal
monitor for
WFPC2, to be run weekly to monitor the health of the
cameras. A variety
of internal exposures are obtained in order to provide a
monitor of the
integrity of the CCD camera electronics in both bays (both
gain 7 and
gain 15 -- to test stability of gains and bias levels), a
test for
quantum efficiency in the CCDs, and a monitor for possible
buildup of
contaminants on the CCD windows. These also provide raw
data for
generating annual super-bias reference files for the
calibration
pipeline.
FGS 11789
An Astrometric Calibration of Population II Distance
Indicators
In 2002 HST produced a highly precise parallax for RR
Lyrae. That
measurement resulted in an absolute magnitude, M(V)=
0.61+/-0.11, a
useful result, judged by the over ten refereed citations
each year
since. It is, however, unsatisfactory to have the direct,
parallax-based, distance scale of Population II variables
based on a
single star. We propose, therefore, to obtain the
parallaxes of four
additional RR Lyrae stars and two Population II Cepheids,
or
stars. The Population II Cepheids lie with the RR Lyrae
stars on a
common K-band Period-Luminosity relation. Using these
parallaxes to
inform that relationship, we anticipate a zero-point error
of 0.04
magnitude. This result should greatly strengthen
confidence in the
Population II distance scale and increase our
understanding of RR Lyrae
star and Pop II Cepheid astrophysics.
ACS/SBC 11324
UV Contamination Monitor
The observations consist of imaging and spectroscopy with
SBC of the
cluster NGC 6681 in order to monitor the temporal
evolution of the UV
sensitivity of the SBC.
WFPC2 11316
HST Cycle 16 & Pre-SM4 Optical Monitor
This is a continuation of the Cycle 15 & pre-SM4
Optical Monitor, 11020.
Please see that proposal for a more complete description
of the
observing strategy. The 6 visits comprising this proposal
observe two
single standard stars with WFPC2/PC in order to establish
overall OTA
focal length for the purposes of focus maintenance. The
goal of this
monitoring before SM4 is to establish a best estimate of
the OTA focus
entering SMOV.
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.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
11787 - GSAcq(2,1,1) scheduled at 123/15:36:52 failed due
to receiving stop
flags QF2STOPF and QSTOP on FGS 2.
Observations affected: ACS 4, Proposal ID #
11982
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSAcq 21 20
FGS REAcq 16 16
OBAD with Maneuver 74 74
SIGNIFICANT EVENTS: (None)