Status Report

NASA Hubble Space Telescope Daily Report # 3602

By SpaceRef Editor
May 3, 2004
Filed under , ,
NASA Hubble Space Telescope Daily Report # 3602

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science





CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
development of hot pixels and test for any source of noise in ACS CCD
detectors. This programme will be executed once a day for the entire
lifetime of ACS.

ACS/WFC 9765

The Dusty ISM Substructure in Nearby Spiral Galaxies

We propose an ACS V&I imaging snapshot survey of all nearby edge-on
spiral galaxies in order to measure the small scale structures in
their dust extinction down to the 10pc scale. Dust and molecular gas
are tightly coupled and therefore HST high resolution reddening maps
can reveal information about the cold ISM phase on a scale
inaccessible from the groundby any other means. We have recently
discovered a sudden change in dust lane properties using ground-based
data; all galaxies with rotation speeds in access of 120km/s show dust
lanes, but none of the slower rotators does. This transition may be
caused by a sudden change in the state of the multiphase ISM, and HST
resolution imaging is needed to fully quantify this effect. Analysis
will consist of full radiative transfer modeling of dust extinction
with realistic, fractal like substructure and power spectrum analysis
of the structure from the global to the 10pc scale. By observing a
sample of galaxies with a range in structural parameters we can
quantify how the cold ISM structure changes as function of radius,
rotation speed, local surface density, et cetera. This information is
duly needed with SIRTF soon providing a wealth of information on dust
absorption, but lacking the resolution to determine the small scale
distribution of the dust.


The local Hubble flow and the density field within 6 Mpc

Great progress has been made recently in accurate distance
measurements of nearby galaxies beyond the Local Group based on the
luminosity of the tip of the red giant branch {TRGB}. Over the last
three years, snapshot surveys with HST have provided us with the TRGB
distances for more than a hundred nearby galaxies obtained with an
accuracy of about 10%. The local velocity field within 5 Mpc exhibits
a significant anisotropy which disagrees with a spherical
Virgo-centric flow. The local Hubble flow is very cold, with 1-D rms
deviations of ~30 km/s. Cosmological simulations with Cold Dark Matter
can only realize such low dispersions with a combination of a low mean
density of matter and a substantial component with negative pressure.
There may be a constraint on the equation of state w=-p/rho. Our
observations will concentrate on 116 galaxies whose expected distances
lie within 4 – 6 Mpc, allowing us to trace a Dark Matter distribution
in the Local Volume with twice the information currently available.
The program is a good one for SNAP mode because the order and rate
that the observations are made are not very important, as long as
there is good completion over several years.


A SNAPSHOT Survey of the Hot Interstellar Medium

We propose to obtain SNAPSHOT STIS echelle observations of key tracers
of hot interstellar gas {CIV, NV and SiIV} for selected FUSE Team OVI
survey targets with known UV fluxes. By taking advantage of the
SNAPSHOT observing mode we will efficiently obtain a large number of
spectra suitable for the study of the highly ionized hot component of
the interstellar medium {ISM}. Our goals are to explore the physical
conditions in and distribution of such gas, as well as to explore the
nature of the interfaces between the hot ISM and the other
interstellar gas phases. Using inter–comparisons of the various ionic
ratios for CIV, NV, OVI and SiIV, we will be able to discriminate
between the various models for the production of the highly ionized
gas in the Galactic ISM. The survey will also enable detailed studies
of regions already known to contain hot gas through X-ray emission
measurements {e.g., SNRs and radio loops}. The proposed SNAPSHOT
observations will extend our previous Cycle 9 survey {which was
compromised by the STIS side 1 failure}, and should roughly double the
number of stars for which high quality STIS observations of the
important hot gas tracers are available, enabling us to derive a truly
global view of the hot ISM.

STIS 9506


We propose a STIS G140L spectroscopic Snapshot program of bright
{V<=16.5} AGN not previously observed in the UV to discover new
high-column density {N_H >= 10^15 cm^-2} LyAlpha absorbers in the
local Universe {z <= 0.45}. Many more of these high column density
systems are needed because: {1} They contribute most of the baryons to
the local IGM; {2} They include many of the “warm-hot” absorbers,
thought to be a large baryon reservoir in the local Universe; and {3}
They are most likely to be “associated” with galaxy halos. Because
of their low-z, many of these absorbers can be located relative to
galaxies of known redshifts, allowing an immediate scientific return
from these snapshots. Using these snapshots to select the best
targets, we will obtain COS R~22, 000 spectra to determine the D/H and
metallicity of absorbers in galaxy halos, groups, and voids. We will
use pairs and “constellations” of AGN to determine absorber sizes,
shapes, and covering factors.

STIS 9786

The Next Generation Spectral Library

We propose to continue the Cycle 10 snapshot program to produce a Next
Generation Spectral Library of 600 stars for use in modeling the
integrated light of galaxies and clusters. This program is using the
low dispersion UV and optical gratings of STIS. The library will be
roughly equally divided among four metallicities, very low {[Fe/H] lt
-1.5}, low {[Fe/H] -1.5 to -0.5}, near-solar {[Fe/H] -0.3 to 0.1}, and
super-solar {[Fe/H] gt 0.2}, well-sampling the entire HR-diagram in
each bin. Such a library will surpass all extant compilations and have
lasting archival value, well into the Next Generation Space Telescope
era. Because of the universal utility and community-broad nature of
this venture, we waive the entire proprietary period.

STIS/CCD 10018

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 10020

CCD Bias Monitor – Part 2

Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1,
and 1×1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.


Volatile Abundances and the D/H Ratio in Long-Period Comets

Comet NEAT {C/2001 Q4} is predicted to reach naked-eye visibility in
the spring of 2004, under excellent conditions for observations with
HST. Although predicting cometary magnitudes more than 1 year in
advance is notoriously risky, C/NEAT seems likely to be exceptionally
active, allowing us for the first time to perform sensitive
measurements of the D/H and OD/OH ratios. Accurate measurements of the
deuterium abundance in comets, which can vary in different species,
are crucial for determining if comets retain a signature of their
possible interstellar origin and if they supplied a significant
fraction of the water on Earth. HST observations of C/NEAT will
additionally provide accurate abundances for highly volatile ices in
the nucleus, such as CO, CO2 {via Cameron band emission}, and S2,
which also provide important insights on the comet’s origin and
evolution. This opportunity in cycle 12 is unique in the history of
HST and is unlikely to be repeated during its remaining lifetime.


Towards a global understanding of accretion physics – Clues from an UV
spectroscopic survey of cataclysmic variables

Accretion inflows and outflows are fundamental phenomena in a wide
variety of astrophysical environments, such as Young Stellar Objects,
galactic binaries, and AGN. Observationally, cataclysmic variables
{CVs} are particularly well suited for the study of accretion
processes. We are currently carrying out a Cycle 11 STIS UV
spectroscopic snapshot survey of CVs to fully exploit the diagnostic
potential of these objects for our understanding of accretion physics.
While the data obtained so far are of excellent quality, the number of
targets that will be observed in Cycle 11 is too small for a
statistically significant analysis {only 19 objects out of our 149
accepted Cycle 11 snapshot targets have been observed at the time of
writing}. We propose here to extend this survey into Cycle 12,
building a homogenous database of accretion disc and wind outflow
spectra covering a wide range of mass transfer rates and binary
inclinations. We will analyze these spectra with state-of-the-art
accretion disc model spectra {SYNDISK}, testing our current knowledge
of the accretion disc structure, and, thereby, providing new insight
into the so far not well understood process of viscous dissipation. We
will use our parameterised wind model PYTHON for the analysis of the
radiation driven accretion disc wind spectra, assessing the
fundamental question whether the mass loss rate correlates with the
disc luminosity. In addition, our survey data will identify a number
of systems in which the white dwarf significantly contributes to the
UV flux, permitting an analysis of the impact of mass accretion on the
evolution of these compact stars. This survey will triple the number
of currently available high-quality accretion disc / wind outflow /
accreting white dwarf spectra, and we waive our proprietary rights to
permit a timely use of this database.

WFPC2 10070

WFPC2 CYCLE 12 Supplemental Darks Part 2/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.) None

17146-1 Battery 6 Capacity test scrip (Steps 32-45) @ 120/13:03z
17161-0 Dump ACS Error Log @ 120/18:54z

1229-0 Change Limits MAMA2 Threshold Voltage @ 120/19:45z
1230-0 PRD Updated with new Tables @ 120/20:17z

                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq              15                          15
FGS REacq               01                           01
FHST Update            20                          20


Final FLASH Report for Battery 6 Capacity Test Battery 6 has
sufficiently recovered from its discharge to 23.688 volts. It’s
voltage, pressure, and loadshare, are in family with the other
batteries. At 120/1255 GMT, Battery 6 was placed back on-line in
flight software. The SOC-1 safing test was successfully modified to
represent a 6-battery system and the BM SOC was reset to 305 A-h. The
K2 SPA Trim relay was un-masked at this time and the proper charge
optimization scheme was reinstated. The EPS system is now back to its
nominal configuration in both FSW and Hardware.

SpaceRef staff editor.