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 # 4445
PERIOD
COVERED: UT September 11, 2007 (DOY 254)
OBSERVATIONS
SCHEDULED
ACS/SBC
10810
The
Gas Dissipation Timescale: Constraining Models of Planet Formation
We
propose to constrain planet-formation models by searching for
molecular
hydrogen emission around young {10-50 Myr} solar-type stars
that
have evidence for evolved dust disks. Planet formation models show
that
the presence of gas in disks is crucial to the formation of BOTH
giant
and terrestrial planets, influences dust dynamics, and through
tidal
interactions with giant planets leads to orbital migration.
However,
there is a lack of systematic information on the presence and
lifetime
of gas residing at planet-forming radii. We will use a newly
identified
broad continuum emission feature of molecular hydrogen at
1600
Angstrom to search for residual gas within an orbital radius of
5-10
AU around young stars that have evolved beyond the optically thick
T
Tauri phase. These observations will enable the most sensitive probe
to
date of remant gas in circumstellar disks, detecting surfaces
densites
of ~0.0001 g/cm^2, or less than 10^-5 of the theoretical
"mininum
mass" solar nebula from which our solar system is thought to
have
formed. Our observations are designed to be synergistic with
ongoing
searches for gas emission that is being performed using the
Spitzer
Space Telescope in that the proposed HST observations are ~100
times
more sensitive and will have 50 times higher angular resolution.
These
combined studies will provide the most comprehensive view of
residual
gas in proto-planetary disks and can set important constraints
on
models of planet formation.
FGS
11299
Calibrating
the Mass-Luminosity Relation at the End of the Main Sequence
We
propose to use HST-FGS1R to finish calibrating the mass-luminosity
relation
for stars less massive than 0.5 Msun, with special emphasis on
objects
near the stellar/substellar border. Our goals are to determine
Mv
values to 0.05 magnitude and masses to 5%, and thereby build the
fundamental
database of stellar masses that we will use to test
theoretical
models as never before. This program uses the combination of
HST-
FGS3/FGS1R at optical wavelengths, historical infrared speckle
data,
ground-based parallax work, metallicity studies, and radial
velocity
monitoring to examine nearby, subarcsecond binary systems. The
high
precision separation and position angle measurements with
HST-FGS3/FGS1R
{to 1 mas in the separations} for these faint {V = 10-15}
targets
simply cannot be equaled by any ground-based technique. As a
result
of these measurements, we are deriving high quality luminosities
and
masses for the components in the systems, and characterizing their
spectral
energy distributions from 0.5 to 2.2 microns. One of the
objects,
GJ 1245 C with mass 0.074 +/- 0.002 Msun, is the only object
known
with an accurate dynamical mass less than 0.10 Msun. The payoff of
this
proposal is high because the six systems selected for final
observations
in Cycles 15 and 16 have already been resolved during
Cycles
5-13 with HST FGS3/FGS1R and contain most of the reddest objects
for
which accurate dynamical masses can be determined.
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.
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
11081
RR Lyrae
stars in M31 Globular Clusters: How did the M31 Spiral Galaxy
Form?
The
pulsation properties of the RR Lyrae stars in the globular clusters
of
the Andromeda galaxy {M31} have the potential to provide essential
insight
on the first epoch of the galaxy formation and to trace the
merging
episodes that led to the assembly of M31. Their mean periods
along
with the cluster metallicities can provide an independent estimate
of
the M31 cluster ages and, in turn, of the time scale of the M31 halo
formation,
by comparison with their Milky Way counterparts. We will
observe
RR Lyrae stars in 6 appropriately selected globular clusters of
M31
using WFPC2 to derive periods, light curves, and physical parameters
of
these eyewitnesses of the first epochs of the M31 formation.
WFPC2
11217
The
Light Echoes around V838 Monocerotis
V838
Monocerotis, which burst upon the astronomical scene in early 2002,
is
a completely unanticipated new object. It underwent a large-amplitude
and
very luminous outburst, during which its spectrum remained that of
an
extremely cool supergiant. A rapidly evolving set of light echoes
around
V838 Mon was discovered soon after the outburst, and quickly
became
the most spectacular display of the phenomenon ever seen. These
light
echoes provide the means to accomplish three unique types of
measurements
based on continued HST imaging during the event: {1} Study
effects
of MHD turbulence at high resolution and in 3 dimensions; {2}
Construct
the first unambiguous and fully 3-D map of a circumstellar
dust
envelope in the Milky Way; {3} Study dust physics in a unique
setting
where the spectrum and light curve of the illumination, and the
scattering
angle, are unambiguously known. We have also used our HST
data
to determine the distance to V838 Mon through direct geometric
techniques.
Because of the extreme rarity of light echoes, this is
almost
certainly the only opportunity to achieve such results during the
lifetime
of HST. We propose two visits during Cycle 16, in order to
continue
the mapping of the circumstellar dust and to accomplish the
other
goals listed above.
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.
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
05
05
FGS
REacq
07
07
OBAD
with Maneuver 24
24
SIGNIFICANT
EVENTS: (None)