HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4689
PERIOD COVERED: 5am September 4 - 5am September 5, 2008
(DOY 248/0900z-249/0900z)
OBSERVATIONS SCHEDULED
FGS 11212
Filling the Period Gap for Massive Binaries
The current census of binaries among the massive O-type
stars is
seriously incomplete for systems in the period range from
years to
millennia because the radial velocity variations are too
small and the
angular separations too close for easy detection. Here we
propose to
discover binaries in this observational gap through a
Faint Guidance
Sensor SNAP survey of relatively bright targets listed in
the Galactic O
Star Catalog. Our primary goal is to determine the binary
frequency
among those in the cluster/association, field, and runaway
groups. The
results will help us assess the role of binaries in
massive star
formation and in the processes that lead to the ejection
of massive
stars from their natal clusters. The program will also
lead to the
identification of new, close binaries that will be targets
of long term
spectroscopic and high angular resolution observations to
determine
their masses and distances. The results will also be
important for the
interpretation of the spectra of suspected and newly
identified binary
and multiple systems.
NIC1/NIC2/NIC3 11820
NICMOS Post-SAA Calibration - CR Persistence Part 7
Internals for CR persistence
NIC2 11548
NICMOS Imaging of Protostars in the Orion A Cloud: The
Role of
Environment in Star Formation
We propose NICMOS observations of a sample of 252
protostars identified
in the Orion A cloud with the Spitzer Space Telescope.
These
observations will image the scattered light escaping the
protostellar
envelopes, providing information on the shapes of outflow
cavities, the
inclinations of the protostars, and the overall
morphologies of the
envelopes. In addition, we ask for Spitzer time to obtain
55-95 micron
spectra of 75 of the protostars. Combining these new data
with existing
3.6 to 70 micron photometry and forthcoming 5-40 micron
spectra measured
with the Spitzer Space Telescope, we will determine the
physical
properties of the protostars such as envelope density,
luminosity,
infall rate, and outflow cavity opening angle. By
examining how these
properties vary with stellar density (i.e. clusters vs
groups vs
isolation) and the properties of the surrounding molecular
cloud; we can
directly measure how the surrounding environment
influences protostellar
evolution, and consequently, the formation of stars and
planetary
systems. Ultimately, this data will guide the development
of a theory of
protostellar evolution.
WFPC2 11156
Monitoring Active Atmospheres on Uranus and Neptune
We propose Snapshot observations of Uranus and Neptune to
monitor
changes in their atmospheres on time scales of weeks and
months. Uranus
equinox is only months away, in December 2007. Hubble
Space Telescope
observations during the past several years {Hammel et al.
2005, Icarus
175, 284 and references therein} have revealed strongly
wavelength-
dependent latitudinal structure, the presence of numerous
visible-wavelength cloud features in the northern
hemisphere, at least
one very long-lived discrete cloud in the southern
hemisphere, and in
2006 the first dark spot ever seen on Uranus. Long-term
ground-based
observations {Lockwood and Jerzekiewicz, 2006, Icarus 180,
442; Hammel
and Lockwood 2007, Icarus 186, 291} reveal seasonal
brightness changes
whose origins are not well understood. Recent near- IR
images of
obtained using adaptive optics on the Keck Telescope,
together with HST
observations {Sromovsky et al. 2003, Icarus 163, 256 and
references
therein} which include previous Snapshot programs {GO
8634, 10170,
10534} show a general increase in activity at south
temperate latitudes
until 2004, when
Further Snapshot observations of these two dynamic planets
will
elucidate the nature of long-term changes in their zonal
atmospheric
bands and clarify the processes of formation, evolution,
and dissipation
of discrete albedo features.
WFPC2 11201
Systemic and Internal motions of the Magellanic Clouds:
Third Epoch
Images
In Cycles 11 and 13 we obtained two epochs of ACS/HRC data
for fields in
the Magellanic Clouds centered on background quasars. We
used these data
to determine the proper motions of the LMC and SMC to
better than 5% and
15% respectively. These are by far the best determinations
of the proper
motions of these two galaxies. The results have a number
of unexpected
implications for the Milky Way-LMC-SMC system. The implied
three-dimensional velocities are larger than previously
believed, and
are not much less than the escape velocity in a standard
10^12 solar
mass Milky Way dark halo. Orbit calculations suggest the
Clouds may not
be bound to the Milky Way or may just be on their first
passage, both of
which would be unexpected in view of traditional
interpretations of the
Magellanic Stream. Alternatively, the Milky Way dark halo
may be a
factor of two more massive than previously believed, which
would be
surprising in view of other observational constraints.
Also, the
relative velocity between the LMC and SMC is larger than
expected,
leaving open the possibility that the Clouds may not be
bound to each
other. To further verify and refine our results we now
request an epoch
of WFPC2/PC data for the fields centered on 40 quasars
that have at
least one epoch of ACS imaging. We request execution in
snapshot mode,
as in our previous programs, to ensure the most efficient
use of HST
resources. A third epoch of data of these fields will
provide crucial
information to verify that there are no residual systematic
effects in
our previous measurements. More importantly, it will
increase the time
baseline from 2 to 5 yrs and will increase the number of
fields with at
least two epochs of data. This will reduce our
uncertainties
correspondingly, so that we can better address whether the
Clouds are
indeed bound to each other and to the Milky Way. It will
also allow us
to constrain the internal motions of various populations
within the
Clouds, and will allow us to determine a distance to the
LMC using
rotational parallax.
WFPC2 11544
The Dynamical Legacy of Star Formation
We propose to use WFPC2 to conduct a wide-field imaging
survey of the
young cluster IC348. This program, in combination with
archival HST
observations, will allow us to measure precise proper
motions for
individual cluster members, characterizing the
intra-cluster velocity
dispersion and directly studying the dynamical signatures
of star
formation and early cluster evolution. Our projected
astrometric
precision (~1 mas in each epoch) will allow us to
calculate individual
stellar velocities to unprecedented precision (<0.5
mas/yr; <1 km/s) and
directly relate these velocities to observed spatial
substructure within
the cluster. This survey will also allow us to probe
small-scale star
formation physics by searching for high-velocity stars
ejected from
decaying multiple systems, expanding our knowledge of
multiplicity in
dense environments, and identifying new substellar and
planetary-mass
cluster members based on kinematic membership tests.
WFPC2 11795
WFPC2 Cycle 16 UV Earth Flats
Monitor flat field stability. This proposal obtains
sequences of earth
streak flats to improve the quality of pipeline flat
fields for the
WFPC2 UV filter set. These Earth flats will complement the
UV earth flat
data obtained during cycles 8-15.
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
11
11
FGS REacq
04
04
OBAD with Maneuver
30
30
SIGNIFICANT EVENTS: (None)