Status Report

NASA Hubble Space Telescope Daily Report # 3585

By SpaceRef Editor
April 9, 2004
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




ACS/HRC 9747

An Imaging Survey of the Statistical Frequency of Binaries Among
Exceptionally-Young Dynamical Families in the Main Asteroid Belt

We propose an ambitious SNAPSHOT program to determine the frequency of
binaries among two very young asteroid families in the Main Belt, with
potentially profound implications. These families {of C- and S-type}
have recently been discovered {Nesvorny et al. 2002, Nature 417, 720},
through dynamical modeling, to have been formed at 5.8 MY and 8.3 MY
ago in catastrophic impact events. This is the first time such
precise and young ages have been assigned to a family. Main-belt
binaries are almost certainly produced by collisions, and we would
expect a young family to have a significantly higher frequency of
binaries than the background, because they may not yet have been
destroyed by impact or longer-term gravitational instabilities. In
fact, one of the prime observables from such an event should be the
propensity for satellites. This is the best way that new numerical
models for binary production by collisions {motivated largely by our
ground-based discoveries of satellites among larger asteroids}, can be
validated and calibrated. We will also measure two control clusters,
one being an "old" family, and the other a collection of background
asteroids that do not have a family association, and further compare
with our determined value for the frequency of large main-belt
binaries {2%}. We request visits to 180 targets, using ACS/HRC.

ACS/HRC 9869

X-ray-Bright, Optically Normal Galaxies: The Hidden Truth

Chandra has resolved most of the > 2 keV X-ray background {XRB} into
discrete sources. Ground-based optical studies of these sources have
revealed a substantial population of apparently normal galaxies at
modest redshift, not the Seyfert 2 galaxies predicted by models for
the origin of the XRB. These objects have X-ray spectral properties
and luminosities similar to Seyfert 2s, but emission lines are weak or
absent in their starlight-dominated optical spectra, suggesting the
emergence of a new class of obscured or gas-poor AGNs at moderate
redshifts. However, most of the galaxies in question are distant
enough that their angular sizes are comparable to the slit widths used
in ground-based spectroscopic observations. Thus, it is possible that
these "normal" galaxies are classical Seyfert 2s whose nuclear
spectral features have been overwhelmed {"hidden"} by host galaxy
light. The high angular resolution of HST/STIS offers a unique
opportunity to isolate the nuclei of these objects spatially. STIS
spectra of a small, carefully selected sample of optically "normal"
X-ray galaxies will help clarify the origin of the XRB, which is vital
for understanding the growth of supermassive black holes in galactic


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.


Dwarf Elliptical Galaxies in Nearby Groups: Stellar Populations and

The M81 group is of the nearest galaxy groups, but its properties are
quite different from the Local Group, providing a different
evolutionary environment for its member galaxies. This team has been
studying M81-group analogs to Local Group dwarf elliptical {dE}
galaxies. We observed two M81-group dEs with WFPC2: the results were
published in Caldwell et al. {1998}. These observations revealed the
upper two magnitudes of the red giant branch, yielding distance via
the luminosity of the red giant branch tip, mean abundance via the
mean giant branch color and first assessment of the star formation
history via the frequency of occurrence of upper-AGB stars. Despite
the different environment, the two M81-group dEs follow the Local
Group {absolute magnitude, mean abundance} relation. But without data
for additional dEs in nearby groups, particularly at higher
luminosities, we can’t definitely say whether this relation is
universal or not. Establishing the answer to this question is vital
because the relation is fundamental to theories of dE formation within
dark matter halos, and the general applicability of these theories
requires demonstration that the relation isn’t strongly influenced by
environment. This proposal requests ACS/WFC observations of five
M81-group dEs to resolve this question.


The COSMOS 2-Degree ACS Survey

We will undertake a 2 square degree imaging survey {Cosmic Evolution
Survey — COSMOS} with ACS in the I {F814W} band of the VIMOS
equatorial field. This wide field survey is essential to understand
the interplay between Large Scale Structure {LSS} evolution and the
formation of galaxies, dark matter and AGNs and is the one region of
parameter space completely unexplored at present by HST. The
equatorial field was selected for its accessibility to all
ground-based telescopes and low IR background and because it will
eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS
instrument. The imaging will detect over 2 million objects with I> 27
mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and
extremely red galaxies out to z ~ 5. COSMOS is the only HST project
specifically designed to probe the formation and evolution of
structures ranging from galaxies up to Coma-size clusters in the epoch
of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The
size of the largest structures necessitate the 2 degree field. Our
team is committed to the assembly of several public ancillary datasets
including the optical spectra, deep XMM and VLA imaging, ground-based
optical/IR imaging, UV imaging from GALEX and IR data from SIRTF.
Combining the full-spectrum multiwavelength imaging and spectroscopic
coverage with ACS sub-kpc resolution, COSMOS will be Hubble’s ultimate
legacy for understanding the evolution of both the visible and dark

FGS 9879

An Astrometric Calibration of the Cepheid Period-Luminosity Relation

We propose to measure the parallaxes of 10 Galactic Cepheid variables.
When these parallaxes {with 1-sigma precisions of 10% or better} are
added to our recent HST FGS parallax determination of delta Cep
{Benedict et al 2002}, we anticipate determining the Period-Luminosity
relation zero point with a 0.03 mag precision. In addition to
permitting the test of assumptions that enter into other Cepheid
distance determination techniques, this calibration will reintroduce
Galactic Cepheids as a fundamental step in the extragalactic distance
scale ladder. A Period-Luminosity relation derived from solar
metallicity Cepheids can be applied directly to extragalactic solar
metallicity Cepheids, removing the need to bridge with the Large
Magellanic Cloud and its associated metallicity complications.

S/C/STIS/MA1/MA2 10035

MAMA Fold Distribution

The performance of MAMA microchannel plates can be monitored using a
MAMA fold analysis procedure. The fold analysis provides a measurement
of the distribution of charge cloud sizes incident upon the anode
giving some measure of changes in the pulse-height distribution of the
MCP and, therefore, MCP gain. This proposal executes the same steps as
the STIS MAMA Fold Analysis {8860} during Cycle 9.

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.

STIS/CCD 10026

STIS Sparse Field CTE test-internal {Cycle 12}

CTE measurements are made using the "internal sparse field test",
along the parallel axis. The "POS=" optional parameter, introduced
during cycle 11, is used to provide off-center MSM positionings of
some slits. All exposures are internals.

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.

WFPC2 10067

WFPC2 Cycle 12 Decontaminations and Associated Observations

This proposal is for the monthly WFPC2 decons. Also included are
instrument monitors tied to decons: photometric stability check, focus
monitor, pre- and post-decon internals {bias, intflats, kspots, &
darks}, UV throughput check, VISFLAT sweep, and internal UV flat

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


1160-2 Default Configuration for TMDIAG’s @ 096/14

                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq               05                        05
FGS REacq               04                        04
FHST Update             16                        16


Set-up and Execution of HST FSW 2.5b OAT for RAM Installation,
Back-out, and EEPROM Installation scheduled 097/10:00Z 098/04:00Z with
GDOC, HITT SE, and VEST using CCS F and D Strings with CCS Release and PRD O06300ST and CCS B and C Strings with CCS Release and PRD O06300T. The purpose of this testing is to verify
installation and backout procedures for RAM version of FSW 2.5b in an
operational scenario.

SpaceRef staff editor.