Status Report

NASA Hubble Space Telescope Daily Report #3916

By SpaceRef Editor
August 4, 2005
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT        # 3916

PERIOD COVERED: UT August 03, 2005 (DOY 215)


ACS/HRC 10348

The Production of X-ray Emission in Classical T Tauri Stars

We propose to obtain a 150 ks HETG spectrum of the Classical T Tauri
Star {CTTS} V4046 Sgr. The unknown source of strong X-ray emission
remains a glaring weakness in our understanding of energetics around
young stars. An HETG observation of the CTTS TW Hya suggested that the
physical properties of the hot gas around accreting stars may be
different from solar-like coronae. This difference hints that
accretion may produce most of the X-rays from CTTSs. However, this
tentative conclusion is based on observations of only one CTTS, that
may not be representative of its class. We seek to verify this
conclusion, and to obtain a better understanding of the temperature,
electron density, and abundances of hot gas around CTTSs, by obtaining
a high S/N HETG spectrum of an X-ray bright CTTS

ACS/HRC 10377

ACS Earth Flats

High signal sky flats will be obtained by observing the bright Earth
with the HRC and WFC. These observations will be used to verify the
accuracy of the flats currently used by the pipeline and will provide
a comparison with flats derived via other techniques: L- flats from
stellar observations, sky flats from stacked GO observations, and
internal flats using the calibration lamps. Weekly coronagraphic
monitoring is required to assess the changing position of the spots.

ACS/HRC 10525

Characterizing the Near-UV Environment of M Dwarfs: Implications for
Extrasolar Planetary Searches and Astrobiology

We propose SNAP observations with the ACS HRC PR200L prism, designed
to measure the near ultraviolet emission in a sample of 107 nearby M
dwarfs. The sample spans the mass range from 0.1 – 0.6 solar masses
{temperature range 2200K – 4000K} where the UV energy distributions
vary widely between active and inactive stars. The strength and
distribution of this UV emission can have critical consequences for
the atmospheres of attendant planets. Our proposed observations will
provide desperately needed constraints on models of the habitability
zone and the atmospheres of possible terrestrial planets orbiting M
dwarf hosts, and will be used to sharpen TPF target selection. In
addition, the NUV data will be used in conjunction with existing
optical, FUV and X-ray data to constrain a new generation of M dwarf
atmospheric models, and to explore unanswered questions regarding the
dynamo generation and magnetic heating in these low-mass stars.

ACS/HRC 10547

A SNAP Program to Obtain Complete Wavelength Coverage of Interstellar

We propose a SNAP program to obtain ACS/HRC spectra in the near-UV
{PR200L} and near-IR {G800L} for a set of main sequence B stars with
available IUE UV spectrophotometry, optical photometry, and 2MASS IR
photometry. Together with these existing data, the new observations
will provide complete photometric and spectrophotometric coverage from
1150 to 11000 A and enable us to produce complete extinction curves
from the far-UV to the near-IR, with well-determined values of R{V}.
The proposed set of 50 program sight lines includes the full range of
interstellar extinction curve types and a wide range of color
excesses. The new data will allow us to examine variability in the
near-UV through near-IR spectral regions, including the UV- optical
“knee” and the “Very Broad Structure.” We will examine the response of
these features to different interstellar environments and their
relationship to other curve features. These are largely unexplored
aspects of extinction curves which will provide additional constraints
on the properties of interstellar grains. The curves will be derived
using stellar atmosphere models to represent the intrinsic spectral
energy distributions of the program stars, eliminating the need to
observe unreddened “standard stars.” This approach virtually
eliminates “mismatch error”, allowing us to derive extinction curves
with much higher precision than previously possible. In addition, the
new spectra will provide higher S/N data for the peak of the 2175 A
bump than previously available.


ACS CCDs daily monitor – Cycle 13 – Part 2

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This program will be
for the entire lifetime of ACS.


Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have
relatively fragile test particles which can be used as tracers of the
early dynamical evolution of the outer Solar System. We propose a
Snapshot program using the ACS/HRC that has a potential discovery
efficiency an order of magnitude higher than the HST observations that
have already discovered the majority of known transneptunian binaries.
By more than doubling the number of observed objects in dynamically
hot and cold subpopulations we will be able to answer, with
statistical significance, the question of whether these groups differ
in the abundance of binaries as a result of their particular dynamical
paths into the Kuiper Belt. Today’s Kuiper Belt bears the imprints of
the final stages of giant-planet building and migration; binaries may
offer some of the best preserved evidence of that long-ago era.


Accurate and Robust Calibration of the Extragalactic Distance Scale
with the Maser Galaxy NGC4258 II

The extragalactic distance scale {EDS} is defined by a comparison of
Cepheid Period- Luminosity {PL} relations for nearby galaxies and the
LMC, whose uncertain distance is thereby the SOLE anchor. Studies of
masers orbiting the central black hole in NGC4258 have provided the
most accurate extragalactic distance ever {7.2+/-0.5 Mpc}, and new
radio data and analysis techniques will reduce the uncertainty to < 3.5% {0.07 mag} by 2005. Since this distance is well determined and based on geometric arguments, NGC4258 can provide a much needed new anchor for the EDS. Ultimately, the combination of an independent measurement of H0 and measurements of CMB fluctuations {e.g., WMAP} can be used to directly constrain cosmological parameters including the equation of state of dark energy. In our Cycle 12 proposal, we defined a program spanning two cycles. The Cycle 12 portion was accepted. We have acquired WFC images and are constructing well sampled PL relations in 3 colors {BVI}. The purpose of the Cycle 13 observations is to address systematic sources of error and is crucial for the success of the entire program. To disentangle the effects of reddening and metallicity, and to characterize the effects of blending, we require 50 orbits to obtain H-band photometry {NICMOS/NIC2} and high resolution images {ACS/HRC}.

ACS/WFC 10493

A Survey for Supernovae in Massive High-Redshift Clusters

We propose to measure, to an unprecedented 30% accuracy, the SN-Ia
rate in a sample of massive z=0.5-0.9 galaxy clusters. The SN-Ia rate
is a poorly known observable, especially at high z, and in cluster
environments. The SN rate and its redshift dependence can serve as
powerful discrimiminants for a number of key issues in astrophysics
and cosmology. Our observations will: 1. Put clear constraints on the
characteristic SN-Ia “delay time, ” the typical time between the
formation of a stellar population and the explosion of some of its
members as SNe-Ia. Such constraints can exclude entire categories of
SN-Ia progenitor models, since different models predict different
delays. 2. Help resolve the question of the dominant source of the
high metallicity in the intracluster medium {ICM} – SNe-Ia, or
core-collapse SNe from an early stellar population with a top-heavy
IMF, perhaps those population III stars responsible for the early
re-ionization of the Universe. Since clusters are excellent
laboratories for studying enrichment {they generally have a simple
star-formation history, and matter cannot leave their deep
potentials}, the results will be relevant for understanding metal
enrichment in general, and the possible role of first generation stars
in early Universal enrichment. 3. Reveal, via nuclear variability, the
AGN fraction in clusters at this redshift, to be compared with the
field AGN fraction. This will be valuable input for understanding
black-hole demographics, AGN evolution, and ICM energetics. 4.
Potentially discover intergalactic cluster SNe, which can trace the
stripped stellar population at high z.


The Formation and Evolution of Spirals: An ACS and WFPC2 Imaging
Survey of Nearby Galaxies Over 50% of galaxies in the local universe
are spirals. Yet the star formation histories and evolution of this
crucial population remain poorly understood. We propose to combine
archival data with new ACS/WFC and WFPC2 observations of 11 galaxies,
to tackle a comprehensive investigation of nearby spirals covering the
entire spiral sequence. The new observations will fill a serious
deficiency in HST’s legacy, and maximize the scientific return of
existing HST data. The filter combination of UBVI, and Halpha is ideal
for studying stellar populations, dust properties, and the ISM. Our
immediate scientific objectives are: {i} to use the resolved cluster
populations, both young massive clusters and ancient globular clusters
as a chronometer, to understand how spirals assembled as a function of
time; {ii} study the rapid disruption properties of young clusters;
and {iii} understand dust distributions in spirals from pc to kpc
scales. Each of these goals provides an important step towards
charting the evolution of galaxies, and an essential baseline for
interpreting the galaxy populations being surveyed in both the early
and present universe. The resolution of our survey, which exploits the
excellent imaging capabilities of HST’s two optical cameras, will
enable us to understand the record of star cluster, and galaxy
formation in a level of detail which is not possible for more distant
systems. Finally, the proposed observations will provide a key to
interpret an extensive, multiwavelength archive of space- and ground-
based data at lower spatial resolution {SPITZER, CHANDRA, GALEX,
NICMOS P alpha and H band imaging} for local spirals.

NIC1/NIC2 10410

Anisotropy and obscuration in the near-nuclear regions of powerful
radio galaxies

Despite the success of the orientation-based unified schemes for
powerful radio sources, we are still far from understanding the
distribution of obscuring material in the near-nuclear regions of such
sources, and how this distribution evolves with radio power. Following
on from our highly successful Cycle 7 pilot observations of Cygnus A,
we propose a near-IR polarimetric survey of a complete sample of
powerful radio galaxies in order map the near-nuclear illumination
cones, and investigate the distribution of obscuring material on a 0.1
to 1kpc scale. In particular, the observations will allow us to test
the “receding torus model” which predicts that the opening angles of
the illumination cones are smaller in low redshift/low power radio
galaxies than in their high redshift/high power counterparts.We will
also investigate whether AGN- and jet-driven outflows have a
substantial effect on distribution of obscuring material by “hollowing
out” the quasar illumination cones in the more powerful sources.
Finally, by using our polarization maps to search for signs of
intrinsic anisotropy in the near-IR continuum within the cones, we
will investigate the geometry of the near-IR continuum emitting
regions close to the quasar nuclei. These observations are not only
crucial for our understanding of radio source unification, but also
provide key information about the effects of AGN-induced outflows on
the ISM of the host galaxies.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration – CR Persistence Part 4

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 DARKSs. 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 10176

Coronagraphic Survey for Giant Planets Around Nearby Young Stars

A systematic imaging search for extra-solar Jovian planets is now
possible thanks to recent progress in identifying “young stars near
Earth”. For most of the proposed young {<~ 30 Myrs} and nearby {<~ 60 pc} targets, we can detect a few Jupiter-mass planets as close as a few tens of AUs from the primary stars. This represents the first time that potential analogs of our solar system - that is planetary systems with giant planets having semi-major axes comparable to those of the four giant planets of the Solar System - come within the grasp of existing instrumentation. Our proposed targets have not been observed for planets with the Hubble Space Telescope previously. Considering the very successful earlier NICMOS observations of low mass brown dwarfs and planetary disks among members of the TW Hydrae Association, a fair fraction of our targets should also turn out to posses low mass brown dwarfs, giant planets, or dusty planetary disks because our targets are similar to {or even better than} the TW Hydrae stars in terms of youth and proximity to Earth. Should HST time be awarded and planetary mass candidates be found, proper motion follow-up of candidate planets will be done with ground-based AOs.

NIC3 10406

NICMOS Imaging of Massive Galaxies at z ~ 2

We propose NICMOS F160W imaging of a sample of massive red galaxies
from the Gemini Deep Deep Survey. These galaxies dominate the stellar
mass density at 1.5< z < 2 and are our best link to early galaxy formation. The NICMOS images will be used in conjunction with our ACS images and deep Gemini spectra to examine the formation and early evolution of massive ellpitcal galaxy progenitors. We waive all propretary rights to the data and wil make them available on our web site as we have done with the Gemini Deep Deep Survey spectra, catalogs and ACS images.


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be

HSTARS: (None)



                                 SCHEDULED     SUCCESSFUL 
 FGS Gsacq                     10                      10 
 FGS Reacq                       8                        8 
 FHST Update                   17                      17         


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