Status Report

NASA Hubble Space Telescope Daily Report #3899

By SpaceRef Editor
July 21, 2005
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT July 11, 2005 (DOY 192)

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 10545

Icy planetoids of the outer solar system

Early HST studies of satellites of Kuiper belt object focussed on the
50-200 km objects that were the largest known at the time. In the past
3 years we have discovered a population of much more rare and much
larger {500-2000+ km} icy planetoids in the Kuiper belt. These objects
are the largest and brightest known in the Kuiper belt and, in the era
when we now know of more than 1000 Kuiper belt objects, these few
planetoids are likely to be the focus of much of the research on
physical properties of the outer solar system for years to come. We
are currently engaged in an intensive program involving Spitzer, Keck,
and other telescopes to study the physical and dynamical properties of
this new population. HST is uniquely capable of addressing one
parameter fundamental to completing the physical picture of these
planetoids: the existence and size of any satellites. The detection
and characterization of satellites to these large planetoids would
allow us to address unique issues critical to the formation and
evolution of the outer solar system, including the measurement of
densities, internal properties, sizes and shapes of these objects, the
study of binary formation as a function of primary size, and the
context of the Pluto-Charon binary. For these bright objects, a
satellite search takes less than a full orbit, allowing the
opportunity for a new project on UV spectroscopy of the planetoids to
piggyback at no added time cost. This poorly explored spectral range
has the potential to show unique signatures of trapped gasses,
cosmochemically important ices, and complex organic materials.

ACS/HRC/NIC3 10182

Towards a Comprehensive Understanding of Type Ia Supernovae: The
Necessity of UV Observations

Type Ia supernovae {SNe Ia} are very important to many diverse areas
of astrophysics, from the chemical evolution of galaxies to
observational cosmology which led to the discovery of dark energy and
the accelerating Universe. However, the utility of SNe Ia as
cosmological probes depends on the degree of our understanding of SN
Ia physics, and various systematic effects such as cosmic chemical
evolution. At present, the progenitors of SNe Ia and the exact
explosion mechanisms are still poorly understood, as are evolutionary
effects on SN Ia peak luminosities. Since early-time UV spectra and
light curves of nearby SNe Ia can directly address these questions, we
propose an approach consisting of two observational components: {1}
Detailed studies of two very bright, young, nearby SNe Ia with HST UV
spectroscopy at 13 epochs within the first 1.5 months after discovery;
and {2} studies of correlations with luminosity for five somewhat more
distant Hubble-flow SNe Ia, for which relative luminosities can be
determined with precision, using 8 epochs of HST UV spectroscopy
and/or broad-band imaging. The HST data, along with extensive
ground-based optical to near-IR observations, will be analyzed with
state-of-the-art models to probe SN Ia explosion physics and constrain
the nature of the progenitors. The results will form the basis for the
next phase of precision cosmology measurements using SNe Ia, allowing
us to more fully capitalize on the substantial past {and future}
investments of time made with HST in observations of high-redshift SNe


The Gas Environment of Comet 9P/Tempel 1 During the Deep Impact

This program consists of a series of observations of periodic comet
9P/Tempel 1 in conjunction with NASA’s Deep Impact mission. This
mission is a spacecraft that will release a 360 kg impactor into the
nucleus of the comet on July 4, 2005. Our primary objective is to
study the generation and evolution of the gaseous coma resulting from
this impact. A secondary objective was to obtain wide-band images of
the visual outburst resulting from the impact. The spectroscopic data
can be obtained using two of the prism modes of the ACS’s HRC/PR200L
and SBC/PR130L.


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.


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 10135

Unveiling the Progenitors and Physics of Cosmic Explosions

GRBs and XRFs are clearly highly asymmetric explosions and require a
long-lived power source {central engine}. In contrast, nearby
core-collapse events are essentially spherical explosions. However,
the failure of spherical neutrino driven collapses has led to the idea
that asymmetric energy release is essential for the explosion. The
recent finding of a Type Ic SN in GRB 030329, the association of the
low energy event GRB 980425 with SN 1998bw, the theoretical
development discussed above and the rise of collapsar models make it
timely to consider whether all these explosions contain engines. Given
the uncertainties in theoretical modeling it is clear that
observations are needed to guide models. A priori there is little
reason to expect connection between the ultra- relativistic jet that
powers the GRB and the explosive nucleosynthesis of the ~0.5 solar
masses of Nickel-56 that powers the accompanying supernova. We propose
a comprehensive program of ACS photometric searches {and measurements}
for SNe associated with GRBs and XRFs. In concert, we will undertake
ground-based spectroscopy to determine velocity widths, and measure
engine parameters from pan- chromatic afterglow observations. Our goal
is to produce a comprehensive database of engine and SN physical
parameters against which theoretical modeling will be guided.

ACS/WFC 10235

Dark vs. luminous matter in the CenA/M83 galaxy complex

The distribution of dark vs. luminous matter on scales of 0.1-1.0 Mpc
remains poorly understood. For a nearby group, the total mass can be
determined from the radius of “the zero-velocity surface”, which
separates the group from the general Hubble flow. This new method
requires the measurement of accurate distances and radial velocities
of galaxies around the group, but gives total mass estimates
independent of assumptions about the state of relaxation or orbital
characteristics. The mass pertains to the group at the full scale to
which it is bound. Upon application in several nearest groups, the
method yields mass estimates in agreement with the sum of the virial
masses of subcomponents. However, the typical total M/L ratio for the
nearby groups of ~30 Mo/Lo implies a local mean density of matter
which is only 1/7 the canonical global density . The nearby complex of
galaxies around Cen A and M83 resembles our Local Group by the
dumb-bell concentration of objects around a pair of dominant galaxies.
Accurate distances have been acquired recently for ~20 group members
by the TRGB method using HST. We will measure TRGB distances to the 17
remaining galaxies in the region. These observations will constrain
the dynamical state of the halo surrounding the nearest giant E-galaxy
Cen A, providing a comparison with the halos of the nearest spirals.

ACS/WFC 10634

White Dwarf Cooling Physics: Calibrating the Clock

We know approximate ages for the Galactic disk from white dwarf
cooling theory applied to local white dwarfs and for the Galactic halo
from main sequence stellar evolutionary theory applied to star
clusters. However, the two chronometers are not cross-calibrated to
the same absolute scale; our observations will perform this
cross-calibration and improve the precision of both chronometers. We
propose to use HST/ACS photometry of white dwarfs in five moderately
old open cluster {0.6-2.2 Gyr}, along with all available up-to-date
white dwarf interior and atmosphere models and a powerful new
statistical approach, to compare main sequence evolutionary theory and
white dwarf cooling theory. This comparison will be done in such a
manner as to test white dwarf crystallization and carbon/oxygen phase
separation, as well as main sequence models in the range where they
are sensitive to the degree of core overshooting and where PP burning
transitions to CNO burning. This confrontation is essential before we
can accurately and precisely apply white dwarf cosmochronometry to the
disk and halo field populations and to globular clusters. Past support
by HST for white dwarf ages in globular clusters {123 orbits for M4
and a similarly large scheduled campaign for NGC 6397} will only be
fully levereged by ensuring that both stellar chronometers are
calibrated to the same age scale. Only then can white dwarf
chronometers live up to their potential as fundamental, independent,
and new age estimators for the Galaxy.

NIC2 10177

Solar Systems In Formation: A NICMOS Coronagraphic Survey of
Protoplanetary and Debris Disks Until recently, despite decades of
concerted effort applied to understanding the formation processes that
gave birth to our solar system, the detailed morphology of
circumstellar material that must eventually form planets has been
virtually impossible to discern. The advent of high contrast,
coronagraphic imaging as implemented with the instruments aboard HST
has dramatically enhanced our understanding of natal planetary system
formation. Even so, only a handful of evolved disks {~ 1 Myr and
older} have been imaged and spatially resolved in light scattered from
their constituent grains. To elucidate the physical processes and
properties in potentially planet-forming circumstellar disks, and to
understand the nature and evolution of their grains, a larger
spatially resolved and photometrically reliable sample of such systems
must be observed. Thus, we propose a highly sensitive circumstellar
disk imaging survey of a well-defined and carefully selected sample of
YSOs {1-10 Myr T Tau and HAeBe stars} and {> app 10 Myr} main sequence
stars, to probe the posited epoch of planetary system formation, and
to provide this critically needed imagery. Our resolved images will
shed light on the spatial distributions of the dust in these thermally
emissive disks. In combination with their long wavelength SEDs the
physical properties of the grains will be discerned, or constrained by
our photometrically accurate surface brightness sensitivity limits for
faint disks which elude detection. Our sample builds on the success of
the exploratory GTO 7233 program, using two-roll per orbit
PSF-subtracted NICMOS coronagraphy to provide the highest detection
sensitivity to the smallest disks around bright stars which can be
imaged with HST. Our sample will discriminate between proposed
evolutionary scenarios while providing a legacy of cataloged
morphologies for interpreting mid- and far-IR SEDs that the recently
launched Spitzer Space Telescope will deliver.

WFPC2 10359

WFPC2 CYCLE 13 Standard Darks

This dark calibration program obtains dark frames every week in order
to provide data for the ongoing calibration of the CCD dark current
rate, and to monitor and characterize the evolution of hot pixels.
Over an extended period these data will also provide a monitor of
radiation damage to the CCDs.


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


#9888 – GSACQ(2,3,2) FL backup, scan step limit exceeded on FGS2 @
192/2155z GSACQ(2,3,2) at 192/21:52:39 ended in fine lock (FL) backup
on FGS 2 due to scan step limit exceeded twice on FGS 2 at 21:55:15
and 21:57:16.


#17469-1 – Real Time Map @ 193/0204z


                SCHEDULED     SUCCESSFUL 
 FGS Gsacq         10            10 
 FGS Reacq          5             5 
 FHST Update       18            18 


SpaceRef staff editor.