Status Report

NASA Hubble Space Telescope Daily Report # 3535

By SpaceRef Editor
January 23, 2004
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




ACS 9984

Cosmic Shear With ACS Pure Parallels

Small distortions in the shapes of background galaxies by foreground
mass provide a powerful method of directly measuring the amount and
distribution of dark matter. Several groups have recently detected
this weak lensing by large-scale structure, also called cosmic shear.
The high resolution and sensitivity of HST/ACS provide a unique
opportunity to measure cosmic shear accurately on small scales. Using
260 parallel orbits in Sloan textiti {F775W} we will measure for the
first time: beginlistosetlength sep0cm setlengthemsep0cm setlength
opsep0cm em the cosmic shear variance on scales <0.7 arcmin, em the
skewness of the shear distribution, and em the magnification effect.
endlist Our measurements will determine the amplitude of the mass
power spectrum sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20,
and the mass density Omega_m with s/n=4. They will be done at small
angular scales where non-linear effects dominate the power spectrum,
providing a test of the gravitational instability paradigm for
structure formation. Measurements on these scales are not possible
from the ground, because of the systematic effects induced by PSF
smearing from seeing. Having many independent lines of sight reduces
the uncertainty due to cosmic variance, making parallel observations


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.


Evolution of Young Stellar Outflows: XZ Tauri and HH 30

Our understanding of jet physics, whether at small {young stellar
outflows} or large {galactic outflows} scales is reflected by our
ability to model the dynamics of the interaction of a jet with its
surroundings and itself. These models must be constrained by
observations, which have typically shown slow, long-timescale changes.
However, a unique opportunity to examine rapidly varying jet dynamics
is available with an established history. XZ Tauri and HH 30 represent
two substantially different young stellar outflows that have been
simultaneously imaged by HST/WFPC2 over 6 epochs spanning 7 years. XZ
Tau is a binary T Tauri system in which both stars are jet sources and
have somehow created an amazing outflow that has undergone dramatic
changes {turn-on of limb brightening, deceleration, interactions with
the collimated stellar jets}. In comparison, the textbook protostellar
disk of HH 30 emits a well-collimated, knotty bipolar jet, in which
motions and knot mergers can be measured over timescales as short as a
year. We wish to continue yearly monitoring of this unique field with
ACS/WFC, and apply hydrodynamic jet models to reproduce the


The role of dark matter and intracluster gas in galaxy formation and
cluster evolution

We propose a fully-sampled mosaic of 41 ACS images to survey galaxy
morphologies and measure weak lensing signals to the turn-around
radius in the X-ray luminous cluster, MS0451-03 {z=0.54}. The aim is
to isolate the physical processes which affect the evolution of
cluster galaxy morphologies in the context of well-defined dynamical
system. The study will be used in contrast to a successful campaign
undertaken in Cycle 9 on a optically-selected target. By comparing
morphologies with spectroscopic and Chandra X-ray data, we will
quantify the role of the intracluster medium and associated
substructures and establish the timescales and physical regions within
which the various environmental processes occur.


An ACS/WFC H-alpha Survey of the Orion Nebula

We propose to survey nearly 500 square arcminutes of the Orion Nebula
in H-alpha using the ACS/WFC, increasing the sky coverage by an order
of magnitude over the sum of all previous HST observations. This
survey will, for the first time, sample the majority of young stars
and circumstellar environments in the extended Trapezium cluster of 2,
000 low-mass stars. Our primary goal is to determine the survival rate
and statistical properties of protoplanetary disks in the type of
radiation field and dynamical environment in which most stars are
born. The survey will be used to search for new silhouette disks,
bright proplyds, microjets, large-scale outflows, and to characterize
the properties of these objects as a function of location in the
nebula. We will determine accurate proper motions in regions where
previous HST data exist. However, 90% of our fields will be observed
with HST for the first time. This survey will provide the first
complete census of pre-main sequence objects and outflows in an HII
region and will constrain the extent of hazards to planet formation in
such environments. The images will also provide a legacy for future
stellar and nebular variability studies and proper motion measurements
by providing a first epoch data base.

NIC/NIC3 9865

The NICMOS Parallel Observing Program

We propose to continue managing the NICMOS pure parallel program.
Based on our experience, we are well prepared to make optimal use of
the parallel opportunities. The improved sensitivity and efficiency of
our observations will substantially increase the number of
line-emitting galaxies detected. As our previous work has
demonstrated, the most frequently detected line is Halpha at
0.7<z<1.9, which provides an excellent measure of current star
formation rate. We will also detect star-forming and active galaxies
in other redshift ranges using other emission lines. The grism
observations will produce by far the best available Halpha luminosity
functions over the crucial–but poorly observed–redshift range where
galaxies appear to have assembled most of their stellar mass. This key
process of galaxy evolution needs to be studied with IR data; we found
that observations at shorter wavelengths appear to have missed a large
fraction of the star-formation in galaxies, due to dust reddening. We
will also obtain deep F110W and F160W images, to examine the space
densities and morphologies of faint red galaxies. In addition to
carrying out the public parallels, we will make the fully reduced and
calibrated images and spectra available on-line, with some
ground-based data for the deepest parallel fields included.

NIC2 9752

A Search for the Exciting Sources in OMC-1 through NICMOS Polarization

Orion contains the site of the nearest region of massive star
formation to the Sun; only here can this pivotal process in galactic
evolution be studied at the highest resolution. There are 10^5 solar
luminosities of radiation emitted from the Orion Molecular Cloud
{OMC-1}, possibly from a young massive star or protostar, or possibly
from several, less luminous sources. Either way, the powering
source{s} in the closest site of massive star formation has still not
yet been identified. Here we propose to apply a new tool to determine
which, of several prospective sources, might prove to be the heart of
OMC-1. The sources cannot be seen directly because they lie in, or
behind, a warm, dense molecular cloud. However, their presence can be
inferred in polarized light, through the manner in which light is
scattered off neighboring clouds. Heretofore, the spatial resolution
has not been adequate to identify the locations of individual stars.
We propose to use the NICMOS polarizers combined with the high spatial
resolution of HST to achieve this, in spite of the high density of
candidate objects in the core of Orion. The demands of accurately
measuring the polarization vectors of small, diffuse objects relative
to the surrounding background from dust-scattered light requires the
high Strehl ratio and stable point-spread function only achievable
from space.


NICMOS Post-SAA calibration – CR Persistence Part 2

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.

STIS/CCD 10017

CCD Dark Monitor-Part 1

Monitor the darks for the STIS CCD.

STIS/CCD 10019

CCD Bias Monitor – Part 1

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.

STIS/CCD 10085

STIS Pure Parallel Imaging Program: Cycle 12

This is the default archival pure parallel program for STIS during
cycle 12.


Far-UV Spectrum and Pulsations of PSR 0656+14: Thermal vs. Nonthermal

The brightest middle-aged pulsar PSR 0656+14 has been studied at
near-IR/optical/near-UV and X-ray wavelengths. Its multiwavelength
spectral distribution indicates that both surface thermal emission and
nonthermal magnetospheric processes are contributing to the observed
radiation. To separate the thermal and nonthermal components and
investigate their properties, we propose to study the spectrum and
pulsations of the pulsar with the STIS/FUV-MAMA detector in the
wavelength range 1150–1700 AA, where it has never been observed.
Combined with the previous HST and X-ray measurements of this pulsar,
this study will go a long way toward quantifying thermal evolution of
neutron stars, constraining the composition and equation of state of
the superdense matter in the neutron star interiors, and understanding
the acceleration and radiation mechanisms in pulsar magnetospheres.


Probing IGM Phases, Metals, and the Cosmic Web with New SDSS QSOs

We propose STIS G140L SNAPSHOT observations of 100 new z < 1 QSOs from
the Sloan Digital Sky Survey for studies of the IGM. These targets
will be chosen to simultaneously maximize IGM pathlength and to form
closely spaced groups of 2-8 QSO sightlines within 1 h^-1 Mpc of a
foreground galaxy. These observations will, in the long term, provide
a rich database of target QSOs for detailed study by COS of the IGM
phases, metallicity, and relationship to the large scale structure. In
the near term, these observations will detect up to 10 Lyman alpha
clouds with N_HI > 10^14 and 3 clouds with N_HI > 10^15, per target.
Thus they will provide an immediate test of filamentary structure in
the "cosmic web" within 1 h^-1 Mpc of galaxies. We ask for 22 minute
exposures for each target with STIS/G140L to obtain S/N = 5-16 for
these V = 16 – 18 QSOs. These observations will be sensitive to Lyman
alpha equivalent widths ranging from 300 mA for the brighter sources
to 600 mA at the fainter end. These targets represent a Deltaz
pathlength of 17 {at 50% yield}, with Deltaz = 10 in the range where
Lya, Lyb, and O VI lie in the HST band. These observations will also
refine predictions of the FUV flux of QSOs based on the larger SDSS
sample and will estimate the degree to which such factors as intrinsic
and Galactic extinction, variability, and intervening absorption can
be controlled. If successful, this technique could make
UV-prequalification SNAPs of QSOs obsolete, at a significant savings
of HST time. Our observations lie at the median duration for SNAPs,
and in the range most likely to be executed. Our program accomplishes
both near- and long-term goals at a relatively low investment of time,
and thus is ideally suited for a SNAP proposal. To ensure maximum
scientific return for our own purposes and for additional science
{HVCs, Galactic halo} we waive the right to a proprietary data period.

STIS/MA1 10034

Cycle 12 MAMA Dark Monitor

This test performs the routine monitoring of the MAMA detector dark
noise. This proposal will provide the primary means of checking on
health of the MAMA detectors systems through frequent monitoring of
the background count rate. The purpose is to look for evidence of
change in dark indicative of detector problem developing.

STIS/MA1 10083

HST UV Images of Saturn’s Aurora Coordinated with Cassini Solar Wind

A key measurement goal of the Cassini mission to Saturn is to obtain
simultaneous solar wind and auroral imaging measurements in a campaign
scheduled for Jan. 2004. Cassini will measure the solar wind
approaching Saturn continuously from 9 Jan. – 6 Feb., but not closer
to Saturn due to competing spacecraft orientation constraints. The
only system capable of imaging Saturn’s aurora in early 2004 will be
HST. In this community DD proposal we request the minimum HST time
needed to support the Cassini mission during the solar wind campaign
with UV images of Saturn’s aurora. Saturn’s magnetosphere is
intermediate between the "closed" Jovian case with large internal
sources of plasma and the Earth’s magnetosphere which is open to solar
wind interactions. Saturn’s aurora has been shown to exhibit large
temporal variations in brightness and morphology from Voyager and HST
observations. Changes of auroral emitted power exceeding one order of
magnitude, dawn brightenings, and latitudinal motions of the main oval
have all been observed. Lacking knowledge of solar wind conditions
near Saturn, it has not been possible to determine its role in
Saturn’s auroral processes, nor the mechanisms controlling the auroral
precipitation. During Cassini’s upcoming approach to Saturn there will
be a unique opportunity to answer these questions. We propose to image
one complete rotation of Saturn to determine the corotational and
longitudinal dependences of the auroral activity. We will then image
the active sector of Saturn once every two days for a total coverage
of 26 days during the Cassini campaign to measure the upstream solar
wind parameters. This is the minimum coverage needed to ensure
observations of the aurora under solar wind pressure variations of
more than a factor of two, based on the solar wind pressure variations
measured by Voyager 2 near Saturn on the declining phase of solar
activity. The team of proposers has carried out a similar coordinated
observing campaign of Jupiter during the Cassini flyby, resulting in a
set of papers and HST images on the cover of Nature on 28 February

STIS/MA1 9790

Separating Activity and Accretion in T Tauri Stars

Due to their unique evolutionary state, the naked {non-accreting} T
Tauri stars {NTTS} are the only real proxies for what the underlying
magnetically active star of a classical TTS {CTTS} system looks like.
Comparative analysis then allows us to separate stellar properties
from accretion properties in CTTS. In addition, the late-type NTTS are
excellent candidates for studying rotation-activity relationships in
fully convective stars and probing the properties of turbulent
dynamos. With the limited data currently available, NTTS appear to be
very magnetically active stars with higher than expected H-alpha/X-ray
flux ratios but lower transition region fluxes relative to other
active stars. However, the data are very incomplete. We will use
HST-STIS observations of transition region line fluxes on 11 fully
convective NTTS to establish the level and structure of dynamo
generated emission in these young stars. In principal, these far
ultraviolet emission lines are sensitive diagnostics of mass accretion
onto CTTS, since accretion shocks on the stellar surface should
produce substantial emission measure at 10^5 – 10^6 K. However, it is
imperative that we first understand the emissions from NTTS before we
can use these lines to study accretion onto CTTS.

WFPC2 10069

WFPC2 CYCLE 12 Supplemental Darks, Part 1/3

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

WFPC2 10084

WFII parallel archive proposal

This is the generic target version of the WFPC2 Archival Pure Parallel
program. The program will be used to take parallel images of random
areas of the sky, following the recommendations of the 2002 Parallels
Working Group.


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



                     SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq         11                       11
FGS REacq         4                          4
FHST Update       21                        21


SpaceRef staff editor.