Status Report

NASA Hubble Space Telescope Daily Report # 3527

By SpaceRef Editor
January 11, 2004
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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
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 ideal.


CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
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 9772

Galaxy Populations at Very Large Cluster Radii: The Outskirts of MS1054-03 at

We propose to use the Advanced Camera for Surveys to image four selected fields
in the outskirts of the rich, X-ray luminous cluster MS1054-03 at z=0.83. The
high-resolution and sensitivity of ACS is required in order to study the
properties of the population of galaxies falling into the cluster for the first
time. By targeting regions of the cluster well beyond the virial radius, we
will: {1} study the transformation of infalling field spirals into cluster
early-types using, e.g., the morphology-density relation to large radii and
low local densities; {2} determine the star-formation histories of those field
galaxies most recently accreted by the cluster, using accurate colors,
morphologies, bulge-to- disk ratios, bulge and disk scale lengths, M/L ratios
and line strengths; and {3} measure the frequency of galaxy-galaxy mergers and
interactions in the infall region. By combining wide-field HST/ACS data with
wide-field multi-object spectroscopy from the Magellan and Keck telescopes, we
can test the predictions made by galaxy formation models, study how field
spirals become early-type cluster members, and better constrain the formation
and evolution of galaxies in both clusters and the field.


Gravitational Microlensing in the NGC 3314A-B Galaxy Pair

Determining the composition of the dark matter that dominates the masses of
galaxies is an important unsolved problem, and the results of the MACHO
Collaboration suggest that some of Milky Way’s dark matter may be in the
form of
very old white dwarfs. However, some have argued that the excess of
events seen by MACHO are due to a larger than expected microlensing rate for
lens stars in the LMC itself or its tidal debris. We propose to address this
question by detecting microlensing events in the line-of-sight galaxy pair NGC
3314 A & B. The large line-of-sight distance between these galaxies gives an
optical depth that is 3-4 orders of magnitude larger than if the source stars
and lenses were in the same galaxy, and the fact that the background galaxy
is a
spiral ensures that there will be a sufficient number of bright, non-variable
source stars. Our proposed observations should have the sensitivity to detect
microlensing by both ordinary stars and dark matter in NGC 3314A {the
galaxy}. If there are dark matter microlensing events to be found, they can be
clearly distinguished from stellar microlensing events because they will occur
outside the visible disk of NGC 3314A. If baryonic dark matter is detected in
NGC 3314A, we will be able to map its radial density variation.


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

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 maser sources
the central black hole in the galaxy NGC4258 have provided the most accurate
extragalactic distance ever {7.2+/- 0.5Mpc}. Since this distance is well
determined and based on GEOMETRIC arguments, NGC4258 can provide a much needed
new anchor for the EDS. We propose multi-epoch BVIH observations of NGC4258 in
order to discover about 100 Cepheids and to characterize their light curves
2-3 times greater accuracy than was previously possible with WFPC2. At 90
{48 in Cycle 12; 42 in Cycle 13}, this is a relatively large program. However,
the result will have a major impact on the EDS, and substantial attention must
be paid to characterization and minimization of systematic errors, as from
metallicity, crowding, and blending. The resulting dataset will be the most
complete for Cepheids in any galaxy yet studied with HST. In an ongoing
NASA-funded program {OSS-SARA}, we are using new analysis techniques and radio
data to reduce uncertainty in the geometric distance to < 3% {0.07 mag}. With
this improved geometric distance and the BVIH data, we will be able to
the zero point of the PL relation ROBUSTLY to <4% {0.09 mag}.

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
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


NICMOS Post-SAA calibration – CR Persistence Part 2

A new procedure proposed to alleviate the CR-persistence problem of NICMOS.
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
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
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

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

STIS/CCD 10085

STIS Pure Parallel Imaging Program: Cycle 12

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

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
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 2002.

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 pixels.

WFPC2 10076

WFPC2 Cycle 12 CTE Monitor

Monitor CTE changes during Cycle 12, including 2X2 binning characterization.

WFPC2 10082

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans

WFPC2 9709

POMS Test Proposal: 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              09                        09
FGS REacq              07                        07
FHST Update            18                        18


HST CCS Release, Case 17 NSSC-1 and SI Operations Regression
Testing scheduled
009/11:00Z – 20:00Z with GDOC, HITT, SE, and VEST using CCS "D" String with
Release and PRD O06300ST. The purpose of this testing is to verify
Release supports normal NSSC-1 and SI commanding in an operational

SpaceRef staff editor.