Notice:
Due to the conversion of some ACS WFC or HRC observations into
WFPC2,
or NICMOS observations after the loss of ACS CCD science
capability
in January, there may be an occasional discrepancy between a
proposal's
listed (and correct) instrument usage and the abstract that
follows
it.
HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4434
PERIOD
COVERED: UT August 24,25,26, 2007 (DOY 236,237,238)
OBSERVATIONS
SCHEDULED
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 DARKs. 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
11329
The
Final SHOE; Completing a Rich Cepheid Field in NGC 1309
The
Cycle 15 SHOES program {GO 10802} is a large HST program allocated
186
orbits to rebuild the distance ladder using NGC 4258 as a new
anchor,
a set of 6 recent, ideal type Ia supernovae and Cepheids in
their
hosts, and NICMOS as a single, homogeneous photometer of long
period
Cepheids. These tools provide the means to achieve a 4%
measurement
of the Hubble constant, an invaluable constraint for cosmic
concordance
fits to dark energy models. Unfortunately, the SHOES NICMOS
integrations
of long period Cepheids in the last and most recent nearby
type
Ia supernova host, NGC 1309, are too short because the preliminary
estimate
of its distance, 30 Mpc, was too low. Our refined estimate now
based
on the full reduction of both our Cycle 14 and 15 ACS data is 36
Mpc,
or 0.4 mag farther. Fortunately, Nature was extremely kind
providing
a single rich NIC2 field in which we can fully make up for the
shortfall
due to its abundance of Cepheids. We are expensing our final 4
orbits
on this field of a dozen P>30 day Cepheids and seek an additional
5 orbits
to reach the depth for measuring the mean F160W magnitudes of
the
long-period Cepheids with the necessary signal-to-noise ratios of
better
than 10.
FGS
11295
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.
WFPC2
11292
The
Ring Plane Crossings of Uranus in 2007
The
rings of Uranus turn edge-on to Earth in May and August 2007. In
between,
we will have a rare opportunity to see the unlit face of the
rings.
With the nine optically thick rings essentially invisible, we
will
observe features and phenomena that are normally lost in their
glare.
We will use this opportunity to search thoroughly for the
embedded
"shepherd" moons long believed to confine the edges of the
rings,
setting a mass limit roughly 10 times smaller than that of the
smallest
shepherd currently known, Cordelia. We will measure the
vertical
thicknesses of the rings and study the faint dust belts only
known
to exist from a single Voyager image. We will also study the
colors
of the newly-discovered faint, outer rings; recent evidence
suggests
that one ring is red and the other blue, implying that each
ring
is dominated by a different set of physical processes. We will
employ
near- edge-on photometry from 2006 and 2007 to derive the
particle
filling factor within the rings, to observe how ring epsilon
responds
to the "traffic jam" as particles pass through its narrowest
point,
and to test the latest models for preserving eccentricities and
apse
alignment within the rings. Moreover, this data set will allow us
to
continue monitoring the motions of the inner moons, which have been
found
to show possibly chaotic orbital variations; by nearly doubling
the
time span of the existing Hubble astrometry, the details of the
variations
will become much clearer.
WFPC2
11289
SL2S:
The Strong Lensing Legacy Survey
Recent
systematic surveys of strong galaxy-galaxy lenses {CLASS, SLACS,
GOODS,
etc.} are producing spectacular results for galaxy masses roughly
below
a transition mass M~10^13 Mo. The observed lens properties and
their
evolution up to z~0.2, consistent with numerical simulations, can
be
described by isothermal elliptical potentials. In contrast, modeling
of giant
arcs in X-ray luminous clusters {halo masses M >~10^13 Mo}
favors
NFW mass profiles, suggesting that dark matter halos are not
significantly
affected by baryon cooling. Until recently, lensing
surveys
were neither deep nor extended enough to probe the intermediate
mass
density regime, which is fundamental for understanding the assembly
of
structures. The CFHT Legacy Survey now covers 125 square degrees, and
thus
offers a large reservoir of strong lenses probing a large range of
mass
densities up to z~1. We have extracted a list of 150 strong lenses
using
the most recent CFHTLS data release via automated procedures.
Following
our first SNAPSHOT proposal in cycle 15, we propose to
continue
the Hubble follow-up targeting a larger list of 130 lensing
candidates.
These are intermediate mass range candidates {between
galaxies
and clusters} that are selected in the redshift range of 0.2-1
with
no a priori X-ray selection. The HST resolution is necessary for
confirming
the lensing candidates, accurate modeling of the lenses, and
probing
the total mass concentration in galaxy groups up to z~1 with the
largest
unbiased sample available to date.
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.
WFPC2
11203
A
Search for Circumstellar Disks and Planetary-Mass Companions around
Brown
Dwarfs in Taurus
During
a 1-orbit program in Cycle 14, we used WFPC2 to obtain the first
direct
image of a circumstellar disk around a brown dwarf. These data
have
provided fundamental new constraints on the formation process of
brown
dwarfs and the properties of their disks. To search for additional
direct
detections of disks around brown dwarfs and to search for
planetary-mass
companions to these objects, we propose a WFPC2 survey of
32
brown dwarfs in the Taurus star-forming region.
WFPC2
11178
Probing
Solar System History with Orbits, Masses, and Colors of
Transneptunian
Binaries
The
recent discovery of numerous transneptunian binaries {TNBs} opens a
window
into dynamical conditions in the protoplanetary disk where they
formed
as well as the history of subsequent events which sculpted the
outer
Solar System and emplaced them onto their present day heliocentric
orbits.
To date, at least 47 TNBs have been discovered, but only about a
dozen
have had their mutual orbits and separate colors determined,
frustrating
their use to investigate numerous important scientific
questions.
The current shortage of data especially cripples scientific
investigations
requiring statistical comparisons among the ensemble
characteristics.
We propose to obtain sufficient astrometry and
photometry
of 23 TNBs to compute their mutual orbits and system masses
and
to determine separate primary and secondary colors, roughly tripling
the
sample for which this information is known, as well as extending it
to
include systems of two near-equal size bodies. To make the most
efficient
possible use of HST, we will use a
optimally
schedule our observations.
NIC3
11080
Exploring
the Scaling Laws of Star Formation
As
a variety of surveys of the local and distant Universe are
approaching
a full census of galaxy populations, our attention needs to
turn
towards understanding and quantifying the physical mechanisms that
trigger
and regulate the large-scale star formation rates {SFRs} in
galaxies.
NIC3/NIC1/NIC2
11059
Flats
Stability
This
calibration proposal is the Cycle 15 NICMOS flat field monitor
program.
A series of camera 1, 2, & 3 flat fields will be obtained to
monitor
the health of the cameras.
WFPC2
11039
Polarizers
Closeout
Observations
of standard stars and a highly polarized reflection nebula
are
made as a final calibration for the WFPC2 polarizers. VISFLATS are
also
obtained.
NIC2
10847
Coronagraphic
Polarimetry of HST-Resolved Debris Disks
We
propose to take full advantage of the recently commissioned
coronagraphic
polarimetry modes of ACS and NICMOS to obtain imaging
polarimetry
of circumstellar debris disks that were imaged previously by
the
HST coronagraphs, but without the polarizers. It is well established
that
stars form in gas-rich protostellar disks, and that the planets of
our
solar system formed from a circum-solar disk. However, the
connection
between the circumstellar disks that we observe around other
stars
and the processes of planet formation is still very uncertain.
Mid-IR
spectral studies have suggested that disk grains are growing in
the
environments of young stellar objects during the putative
planet-formation
epoch. Furthermore, structures revealed in well
resolved
images of circumstellar disks suggest gravitational influences
on
the disks from co-orbital bodies of planetary mass. Unfortunately,
existing
imaging data provides only rudimentary information about the
disk
grains and their environments. Our proposed observations, which can
be
obtained only with HST, will enable us to quantitatively determine
the
sizes of the grains and optical depths as functions of their
location
within the disks {i.e., detailed tomography}. Armed with these
well-determine
physical and geometrical systemic parameters, we will
develop
a set of self- consistent models of disk structures to
investigate
possible interactions between unseen planets and the disks
from
which they formed. Our results will also calibrate models of the
thermal
emission from these disks, that will in turn enable us to infer
the
properties of other debris disks that cannot be spatially resolved
with
current or planned instruments and telescopes.
NIC2
10802
SHOES-Supernovae,
HO, for the Equation of State of Dark energy
The
present uncertainty in the value of the Hubble constant {resulting
in
an uncertainty in Omega_M} and the paucity of
redshifts
exceeding 1 are now the leading obstacles to determining the
nature
of dark energy. We propose a single, integrated set of
observations
for Cycle 15 that will provide a 40% improvement in
constraints
on dark energy. This program will observe known Cepheids in
six
reliable hosts of
uncertainty
in H_0 by a factor of two because of the smaller dispersion
along
the instability strip, the diminished extinction, and the weaker
metallicity
dependence in the infrared. In parallel with ACS, at the
same
time the NICMOS observations are underway, we will discover and
follow
a sample of
measurements,
along with prior constraints from WMAP, will provide a
great
improvement in HST's ability to distinguish between a static,
cosmological
constant and dynamical dark energy. The Hubble Space
Telescope
is the only instrument in the world that can make these IR
measurements
of Cepheids beyond the Local Group, and it is the only
telescope
in the world that can be used to find and follow supernovae at
z
> 1. Our program exploits both of these unique capabilities of HST to
learn
more about one of the greatest mysteries in science.
WFPC2
10789
The
Role of Environment in the Formation of Dwarf Galaxies
Clusters
of galaxies contain an overdensity of dwarfs compared to the
field.
Within galaxy clusters there is also a correlation between the
overdensity
of dwarfs and local galaxy density, such that areas of lower
galaxy
density contain more dwarfs per giant. The origin of these
'extra'
dwarfs is unknown, but a large fraction of them did not form
through
standard collapses early in the universe. Some dwarf ellipticals
in
clusters have metal rich and young {< 6 Gyr} stellar populations
while
others contain old metal poor populations, suggesting multiple
formation
mechanisms and time scales. We propose to test the idea that
dwarfs
descend from galaxies accreted into clusters during the past 8
Gyr
by correlating ages and metallicities of dwarfs with their internal
structures
- spiral arms, bars, and disks. If dwarfs originate from more
massive
galaxies then these features should be common in metal rich and
young
dwarfs. On the other hand, if no correlation is found it would
suggest
that dwarfs form through in-situ collapses of gas in the
intragalactic
medium after the universe was reionized.
WFPC2
10599
Multi-color
imaging of two 1 Gyr old debris disks within 20 pc of the
Sun:
Astrophysical mirrors of our Kuiper Belt
We
report the first scattered light detections of two debris disk around
an
F star and a K star using optical coronagraphy and the Hubble Space
Telescope.
With ages ~1 Gyr, these are the oldest debris disks thus far
seen
in the optical. We propose deep, multi-roll angle coronagraphic
imaging
with HST ACS and NICMOS to confirm and characterize the disks in
terms
of structure and composition. The disks appear to have belt-like
morphology
that is consistent with the existence of planetary companions
or
other perturbing bodies. Since these disks are close to our Kuiper
Belt
in an evolutionary context, detailed understanding of their mass,
structure
and composition will provide a fresh perspective for inferring
the
history and properties of our own trans-Neptunian region.
NIC2
10487
A
Search for Debris Disks in the Coeval Beta Pictoris Moving Group
Resolved
observations of debris disks present us with the opportunity of
studying
planetary evolution in other solar systems. We propose to
search
for debris disks in the Beta Pictoris moving group {8-20 Myrs,
10-50
pc away} , which provides a coeval sample of multiple spectral
types,
and it has already produced two magnificent resolved debris
disks:
AU Mic and Beta Pic. Such coeval sample will provide us with a
snapshop
of the crucial time in disk evolution in which the disk makes
the
transition from optically thick to optically thin, and it will be
useful
to study the stellar mass dependence of the disk evolution.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
10954
- REACQ(2,1,1) failed
REACQ(2,1,1) at 236/11:36:07 failed to RGA control. FGS 1 acquired
fine
lock at 11:40:05 but lost it at 11:42:00. No flags or ESB messages
were
seen. GSACQ(2,1,1) at 08:25:54 was successful as was a previous
REACQ at
10:00:14.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
31
31
FGS
REacq
10
09
OBAD
with Maneuver
82
82
SIGNIFICANT
EVENTS: (None)