HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4792
PERIOD COVERED: 5am February 13 - 5am February 17, 2009
(DOY
044/1000z-048/1000z)
OBSERVATIONS SCHEDULED
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
WFPC2 11967
WFPC2 Imaging of the Lockman Hole
In order to understand galaxy evolution and constrain
theoretical
models, we require both multiwavelength photometry (to
robustly
determine physical parameters such as star formation rates
and stellar
masses) and detailed morphological information. Galaxy
morphology
encodes crucial information about galaxy formation history
and the
physical processes that trigger star formation and AGN
activity, and
high-resolution imaging for large samples of galaxies is
currently only
obtainable with HST. The Lockman Hole has been the target
of extensive
multi-wavelength observations from the X-ray to the radio,
and will be
the target of the deepest wide-area blankfield thermal IR
observations
with Herschel, but currently lacks comprehensive HST
imaging. We propose
to obtain WFPC2 imaging of ~500 arcmin2 of the central
region of the
Lockman Hole in F606W and F814W, to a depth of V606~26.8
and I814~26.
This imaging is crucial in order to characterize the
sources detected at
other wavelengths.
WFPC2 11944 - FGS 11943
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 11797
Supplemental WFPC2 CYCLE 16 Intflat Linearity Check and
Filter Rotation
Anomaly Monitor
Supplemental observations to 11029, to cover period from
Aug 08 to SM4.
Intflat observations will be taken to provide a linearity
check: the
linearity test consists of a series of intflats in F555W,
in each gain
and each shutter. A combination of intflats, visflats, and
earthflats
will be used to check the repeatability of filter wheel
motions.
(Intflat sequences tied to decons, visits 1-18 in prop
10363, have been
moved to the cycle 15 decon proposal 11022 for easier
scheduling.)
Note: long-exposure WFPC2 intflats must be scheduled
during ACS anneals
to prevent stray light from the WFPC2 lamps from
contaminating long ACS
external exposures.
Note: These are supplemental observations to cover June to
SM4 (Oct 8
'08) + 6 months.
WFPC2 11796
WFPC2 Cycle 16 Decontaminations and Associated
Observations
This proposal is for the WFPC2 decons. Also included are
instrument
monitors tied to decons: photometric stability check,
focus monitor,
pre- and post-decon internals (bias, intflats, kspots,
& darks), UV
throughput check, VISFLAT sweep, and internal UV flat
check.
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.
FGS 11788
The Architecture of Exoplanetary Systems
Are all planetary systems coplanar? Concordance cosmogony
makes that
prediction. It is, however, a prediction of extrasolar
planetary system
architecture as yet untested by direct observation for
main sequence
stars other than the Sun. To provide such a test, we
propose to carry
out FGS astrometric studies on four stars hosting seven
companions. Our
understanding of the planet formation process will grow as
we match not
only system architecture, but formed planet mass and true
distance from
the primary with host star characteristics for a wide
variety of host
stars and exoplanet masses.
We propose that a series of FGS astrometric observations
with
demonstrated 1 millisecond of arc per-observation
precision can
establish the degree of coplanarity and component true
masses for four
extrasolar systems: HD 202206 (brown dwarf+planet); HD
128311
(planet+planet), HD 160691 = mu Arae (planet+planet), and
HD 222404AB =
gamma Cephei (planet+star). In each case the companion is
identified as
such by assuming that the minimum mass is the actual mass.
For the last
target, a known stellar binary system, the companion orbit
is stable
only if coplanar with the AB binary orbit.
FGS 11785
Trigonometric Calibration of the Distance Scale for Classical
Novae
The distance scale for classical novae is important for
understanding
the stellar physics of their thermonuclear runaways, their
contribution
to Galactic nucleosynthesis, and their use as
extragalactic standard
candles. Although it is known that there is a relationship
between their
absolute magnitudes at maximum light and their subsequent
rates of
decline--the well-known maximum-magnitude rate-of-decline
(MMRD)
relation--it is difficult to set the zero-point for the
MMRD because of
the very uncertain distances of Galactic novae.
We propose to measure precise trigonometric parallaxes for
the quiescent
remnants of the four nearest classical novae. We will use
the Fine
Guidance Sensors, which are proven to be capable of
measuring parallaxes
with errors of ~0.2 mas, well below what is possible from
the ground.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
11673 - REacq(1,2,2) scheduled at 044/23:45:20 - 23:53:34
resulted in
fine lock backup (1,0,1) using FGS-1 due to (QF2STOPF) stop flag
indication on FGS-2.
Possible observations affected: WFPC 123, 124 Proposal ID#11967.
11677 - GSacq (2,3,3) scheduled from 048/01:31:06 -
01:38:27 resulted in
Fine Lock Back-up (2,0,2).
Possible observations affected: Astrometry Proposal ID#11944
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
27
27
FGS
REacq
29
29
OBAD with Maneuver
112
112
SIGNIFICANT EVENTS: (None)