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Daily Report #4445



 
 
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Old September 13th 07, 11:04 AM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report #4445

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 P30 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 Type Ia supernovae at
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 Type Ia supernovae with NICMOS, reducing the
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 Type Ia supernovae at z 1. Together,
these 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)


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