Status Report

NASA Hubble Space Telescope Daily Report # 3434

By SpaceRef Editor
August 26, 2003
Filed under , ,





ACS 9675

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 9760

ACS Imaging of the Gemini Deep Deep Survey Fields: Galaxy Assembly at
z = 1.5

We are presently carrying out the deepest redshift survey ever
undertaken {the Gemini Deep Deep Survey}. Spectra of extraordinary
quality have been taken in order to obtain redshifts in the so-called
"redshift desert" at 1<z<2. This redshift range corresponds to the
epoch of peak galaxy formation. In this proposal we request 40 orbits
of ACS imaging to determine the morphologies of 100-120 candidate
early-type galaxies with known redshifts in our survey fields. We seek
to determine if these systems are indeed elliptical galaxies and to
link their morphological states to their spectroscopically determined
ages, recent star-formation histories, and to the evolving global
stellar mass function at the peak epoch of galaxy assembly.

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

ACS/HRC 9746

Binary systems in the Kuiper Belt

The properties of the orbits of Kuiper belt object {KBO} satellites
hold keys to fundamental insight into masses and densities of KBOs,
the interaction history of the early solar system, the internal
structure of distant ice-rock bodies, and even the genesis of the
Pluto-Charon binary. Within the past 18 months, 9 KBO satellite
systems have been discovered, allowing for the first time the
possibility of characterizing a sample of KBO satellite orbital
properties. We propose HRC observations to determine satellite orbits
in the 6 best cases. We have carefully devised a strategy for each of
these 6 systems to make maximum use of ground-based observations,
previous HST observations, and the smallest possible number of new HST
observations. Our proposed observations will efficiently provide
highly reliable orbital solutions which are critical to achieving the
scientific promise available from the study of these systems. Our
strategy relies heavily on extensive Monte Carlo simulations to define
optimal times of observing such that each new point obtained gives
maximum leverage for refining the orbital solution. We find that with
this strategy we can provide mass solutions for all 6 systems to an
accuracy of better than 10% using only 25 new HST observations. This
highly efficient program provides extreme scientific output with
optimal use of scarce resources.

ACS/HRC 9823

Rings of Uranus: Dynamics, Particle Properties and Shepherding Moons

We propose to image the rings and small inner satellites of Uranus
using the High Resolution Channel of the ACS. The revolutionary
capabilities of the ACS will allow us to address a variety of
important questions relating to ring properties and ring-moon
interactions. Observations at a range of wavelengths and phase angles
will reveal the opposition surges of these rings and moons, providing
information on color and surface structure. Measurements of the ring
in front of the planet will provide complementary information on
optical depth; any variations of optical depth with wavelength will
reveal the rings’ poorly-constrained population of embedded dust. The
rings of Uranus are closing rapidly as the planet approaches equinox
in 2007, an event that takes place only every 42 years. Using this
opportunity, our observations will be repeated at different solar and
terrestrial tilt angles; this sequence of images will be particularly
valuable for constraining the physical thickness and packing density
of the rings. We will place particular emphasis on the rotational
variations of the Epsilon Ring, whose radial width {and therefore its
packing density} varies by a factor of five. In addition, a set of
deep exposures targeted just off the planet will enable us to detect
any 4-5 km moons embedded within the ring system. Dynamicists invoke
numerous such moons to "shepherd" the many sharp ring boundaries, so
this will serve as a definitive test of the theory.


The Morphological, Photometric, and Spectroscopic Properties of
Intermediate Redshift Cluster Galaxies:

New and fundamental constraints on the evolutionary state of high
redshift clusters will be made by obtaining deep, multiband images
{SDSS r, i, z} over the central 1.5 Mpc regions of seven distant
clusters in the range 0.76 < z < 1.27. The ACS data will allow us to
{1} definitively establish the morphological composition and star
formation rates as functions of clustercentric radius, local density,
x-ray luminosity {obtained from accompanying Chandra, and XMM data},
{2} explore the relationship between substructure, kinematics, and
morphology, {3} strongly constrain the galaxy merger frequency and the
origins of elliptical and S0 galaxies, {4} measure the mass
distribution independently from the light {via gravitational lensing}
enabling comparisons with kinematically derived masses, and {5} study
the evolution of the structure of the brightest cluster members. The
clusters selected for this program already have extensive
spectroscopic observations and NIR imaging is either in hand or
underway from approved ground based programs. To date, the lower part
of this redshift range has only been marginally studied with HST. Our
sample includes the two most distant, spectroscopically confirmed
superclusters and will significantly increase the baseline over which
evolutionary effects can be studied. The data will also be used to
identify very high-z galaxies via their unique spectral properties.

ACS/WFC 9842

A Snapshot Search for Halo Very-Low-Mass Binaries

We propose a snapshot search for binary M subdwarf stars. These nearby
stars have high velocities and low metallicies that identify them as
members of the old Galactic halo {Population II}. ACS imaging is
requested to search for secondary companions. This supplements a
previous snapshot program that only obtained 10 observations. The
observed binary fraction will be compared to the disk M dwarf fraction
to look for differences in star formation. It is likely that a system
suitable for orbital mass determinations will be found. In this case,
future HST observations could determine the first masses for
very-low-mass, low-metallicity stars.

STIS 9606

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS 9608

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.

STIS 9615

Cycle 11 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 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 10000

STIS Pure Parallel Imaging Program: Cycle 12

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

WFPC2 9592

WFPC2 CYCLE 11 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.

WFPC2 9595


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

WFPC2 9596


This calibration proposal is the Cycle 11 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{gain 7 and gain 15}, a test for quantum efficiency in the CCDs, and a
monitor for possible buildup of contaminants on the CCD windows.

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.

WFPC2 9809

Saturn’s rings and small moons on the eve of Cassini

We propose to continue our long-term survey of Saturn’s rings and
small moons to obtain a coherent set of high resolution, multi-color
WFPC2 images of Saturn and its rings during the final year before the
arrival of the Cassini spacecraft at Saturn in mid-2004. Our Cycle
6-11 programs {6806, 7427, 8398, 8660, 8802, and 9341} explored the
rings from their nearly edge-on aspect {southern hemisphere spring} to
summer solstice in late 2002. We now propose to take advantage of the
especially favorable viewing geometry of Cycle 12 to obtain UBVRI,
F255W, and methane-filter PC images of the rings, small moons, and
planet at the lowest phase angle {0.07 degrees} observable to date. A
key goal is to measure for the first time the expected sharp spike in
the opposition brightness of the rings and small moons, which will
characterize the structure and particle properties of the rings and
the surfaces of the satellites. We will also follow the chaotic
behavior of Prometheus and Pandora, two small moons which may be
perturbing each other gravitationally. Here, our goals are to catch
the satellites in the act of any new coupled motions and to determine
the changes in semimajor axis, eccentricity, and orbital inclination
of the moons resulting from their most recent large chaotic
interaction in 2000. This will complete our continuous WFPC2 coverage
of these moons from 1994 until mid-2004, when Cassini’s cameras will
at long last surpass the capabilities of the HST. The Cycle 12
observations will also enable us to determine zonal winds and regional
variations in Saturn’s atmosphere prior to Cassini’s arrival.


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

HSTAR 9125: FHST FM (U2,3FM) Update failure @ 237/18:42:57Z and
18:45:42Z with Error Box results showing "3 FAILED" for mnemonics
QEBSTFG0, QEBSTFG1, and QEBSTFG2. GS Acquisition @ 237/19:09:03Z was
successful. Under investigation.

HSTAR 9126: FHST FM (U2,3FM) Updates @ 238/05:54:57Z and 05:57:42Z
using FHST 2 and FHST 3 (optimal pair 2,3) failed with Error Box
results indicating "3 FAILED" for mnemonics QEBSTFG0, QEBSTFG1, and
QEBSTFG2. Subsequent GS Acquisition (2,3,2) @ 238/06:19:17Z with
Primary FGS Search Radius = 55 arcsec was successful. Under



                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq              08                       08
FGS REacq              06                       06
FHST Update            19                       17               See
# 9125  & Hstar # 9126


HST CCS Release 5.0.3, Case 17, NSSC-1 and SI Operations Regression
testing scheduled 238/11:00Z – 20:00Z with GDOC, HITT, SE, and VEST
using CCS "C" and "D" Strings with PRD O06100R1T. The purpose of this
testing is to verify CCS Release 5.0.3 supports normal NSSC-1 and SI
commanding in an operational scenario.

SpaceRef staff editor.