Status Report

NASA Hubble Space Telescope Daily Report # 3843

By SpaceRef Editor
April 21, 2005
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT        # 3843



ACS/HRC 10391

Wavelength and Flux Calibration of the ACS prisms

The wavelength calibration of the SBC {PR110L and PR130L} and HRC
{PR200L} prisms will be established by observing a planetary nebula in
the LMC and QSOs at carefully selected redshifts. Flux calibrations
will be derived for each prism by observing white dwarf standards.

ACS/HRC 10435

Merger-Induced Populations in Early-Type Galaxy Cores

Hierarchical formation models predict that early-type galaxies are
built up over an extended period from mergers of smaller systems, a
process which should leave long- lived signatures in their light
profiles and stellar population colors. Merger events should have
continued up to relatively recent times {the last 1-5 Gyr}, and many
ellipticals and S0 bulges should therefore show evidence of multiple,
discrete, intermediate-age populations. Although there is substantial
observational support for a dissipational merger origin for some
early-type galaxies, most do not exhibit the expected anomalies in
either their light profiles or color distributions. However, existing
searches {mainly in the V and I bands} have not probed very deeply.
Here we propose high resolution, broad-band, near-ultraviolet
{2500-3400 A} imaging of the cores of bright early-type galaxies. This
is the most sensitive probe available for the detection of
spatially-segregated, multiple population components with ages in the
range 1-5 Gyr. Our sample consists of dust- and AGN-free systems with
both normal and mildly anomalous central light profiles. There is very
little existing information on the near-UV structure of early-type
galaxies, and our program would effectively explore new terrain.


ACS CCDs daily monitor – Cycle 13 – Part 2

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This programme will be
for the entire lifetime of ACS.


Black Hole Growth and the Black Hole Mass — Bulge Relations for AGNs

Recent work has shown that the mass of a black hole is tightly
correlated with the bulge mass of its host galaxy. This relation needs
to be understood in the context of black hole growth in its active
phase. Highly accreting AGNs, like narrow line Seyfert 1 galaxies
{NLS1s}, are found to lie below the black hole mass — bulge velocity
dispersion correlation of normal galaxies and broad line AGNs. This
result was obtained using FWHM{[OIII]} as a surrogate for the bulge
velocity dispersion. To test this result we propose to obtain high
resolution images of 10 NLS1s that do not lie on the black hole
mass–sigma relation and measure accurate bulge parameters {luminosity
and effective radius}. We will obtain an alternate handle on the bulge
velocity dispersion through the fundamental plane relations and also
find the locus of these NLS1s on the black hole mass–bulge luminosity
plane. Testing this result is crucial to understanding the role of
accretion on black hole growth, the observed correlations of the black
hole mass with the bulge, and the formation and evolution of galaxies.

ACS/WFC 10174

Dark-matter halos and evolution of high-z early-type galaxies

Gravitational lensing and stellar dynamics provide two complementary
methods to determine the mass distribution and evolution of luminous
and dark-matter in early-type {E/S0} galaxies. The combined study of
stellar dynamics and gravitational lensing allows one to break
degeneracies inherent to each method separately, providing a clean
probe of the internal structure of massive galaxies. Since most lens
galaxies are at redshifts z=0.1-1.0, they also provide the required
look-back time to study their structural and stellar-population
evolution. We recently analyzed 5 E/S0 lens galaxies between z=0.5 and
1.0, combining exquisite Hubble Space Telescope imaging data with
kinematic data from ground-based Keck spectroscopy, placing the first
precise constraints on the dark- matter mass fraction and its inner
slope beyond the local Universe. To expand the sample to ~30 systems
— required to study potential trends and evolution in the E/S0 mass
profiles — we propose to target the 49 E/S0 lens-galaxy candidates
discovered by Bolton et al. {2004} from the Sloan Digital Sky Survey
{SDSS}. With the average lens rate being 40% and some systems having a
lensing probability close to unity, we expect to discover ~20 strong
gravitational lenses from the sample. This will triple the current
sample of 9 E/S0 systems, with data in hand. With the sample of 30
systems, we will be able to determine the average slope of the
dark-matter and total mass profile of E/S0 galaxies to 10% and 4%
accuracy, respectively. If present, we can simultaneously detect 10%
evolution in the total mass slope with 95% confidence. This will
provide unprecedented constraints on E/S0 galaxies beyond the local
Universe and allow a stringent test of their formation scenarios and
the standard cosmological model.

ACS/WFC 10369

ACS internal CTE monitor

The charge transfer efficiency {CTE} of the ACS CCD detectors will
decline as damage due to on-orbit radiation exposure accumulates. This
degradation will be closely monitored at regular intervals, because it
is likely to determine the useful lifetime of the CCDs. All the data
for this program is acquired using internal targets {lamps} only, so
all of the exposures should be taken during Earth occultation time
{but not during SAA passages}. This program emulates the ACS
pre-flight ground calibration and post-launch SMOV testing {program
8948}, so that results from each epoch can be directly compared.
Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}
data will be obtained over a range of signal levels for both the Wide
Field Channel {WFC}, and the High Resolution Channel {HRC}.

ACS/WFC 10374

ACS photometric Stability

This program consists of three parts. In the first part we will
observe a subset of the ACS white dwarfs with HRC and ACS to verify
repeatability to ~0.2%, because the filter shifts are based on
photometric differences between stars of ~1%. These observations are
also required to establish relative magnitudes of the primary WD
standards at the 0.1% level. Targets should be GD153 and G191B2B,
which seems to have the largest V mag error of ~0.008 mag. One orbit
on the most important filters, including the grism and the prisms,
should be expended with each camera for both stars for a total of 4
orbits. In the second part will observe with HRC and WFC a solar
analog star, P330E, to estimate any shifts in the short and the long
wavelength cutoffs of selected filters. Complete filter bandpasses can
be derived directly from the ratio of grism observations with and
without the filter in place. The grism is on filter wheel 1, while
four filters of interest F330W, F344N, F660N, and F814W are on wheel
2. Each grism observation requires 3 settings: filter alone,
filter+grism, and grism alone. In the third part we obtain high S/N
photometric and spectroscopic observations of three red stars, VB-8
{M7}, 2M0038+18 {L3.5} and 2M0559-14 {T5} with HRC and WFC to verify
the photometry at the new standard position and to obtain accurate
calibration {1% or better} of the grism spectra.

ACS/WFC 10412

The host galaxies of dust-reddened quasars

We have used the 2MASS near-infrared and FIRST radio surveys, together
with the Palomar Observatory Sky Survey plates to select a sample of
dust-reddened, radio- intermediate quasars. We wish to use ACS to
study the host galaxies of these quasars. The dust reddening of the
quasars makes it possible to study the hosts at rest-frame optical-UV
wavelengths much more easily than the hosts of normal quasars of
similar bolometric luminosity. Our study will compare the hosts of our
dust-reddened quasars to those of normal quasars from the HST archive
to test the hypothesis that dust-reddened quasars are young objects,
whose hosts still show morphological evidence of recent merger events
which triggered the quasar.


The Formation and Evolution of Spirals: An ACS and WFPC2 Imaging
Survey of Nearby Galaxies

Over 50% of galaxies in the local universe are spirals. Yet the star
formation histories and evolution of this crucial population remain
poorly understood. We propose to combine archival data with new
ACS/WFC and WFPC2 observations of 11 galaxies, to tackle a
comprehensive investigation of nearby spirals covering the entire
spiral sequence. The new observations will fill a serious deficiency
in HST’s legacy, and maximize the scientific return of existing HST
data. The filter combination of UBVI, and Halpha is ideal for studying
stellar populations, dust properties, and the ISM. Our immediate
scientific objectives are: {i} to use the resolved cluster
populations, both young massive clusters and ancient globular clusters
as a chronometer, to understand how spirals assembled as a function of
time; {ii} study the rapid disruption properties of young clusters;
and {iii} understand dust distributions in spirals from pc to kpc
scales. Each of these goals provides an important step towards
charting the evolution of galaxies, and an essential baseline for
interpreting the galaxy populations being surveyed in both the early
and present universe. The resolution of our survey, which exploits the
excellent imaging capabilities of HST’s two optical cameras, will
enable us to understand the record of star cluster, and galaxy
formation in a level of detail which is not possible for more distant
systems. Finally, the proposed observations will provide a key to
interpret an extensive, multiwavelength archive of space- and ground-
based data at lower spatial resolution {SPITZER, CHANDRA, GALEX,
NICMOS P alpha and H band imaging} for local spirals.

FGS 10106

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.

FGS 10386

Long Term Monitoring of FGS1r in Position Mode

It is known from our experience with FGS3, and later with FGS1r, that
an FGS on orbit experiences long term evolution, presumably due to
disorption of water from the instrument’s graphite epoxy composites.
This manifests principally as a change in the plate scale and
secondarily as a change in the geometric distortions. These effects
are well modeled by adjustments to the rhoA and kA parameters which
are used to transform the star selector servo angles into FGS {x, y}
detector space coordinates. By observing the relative positions of
selected stars in a standard cluster at a fixed telescope pointing and
orientation, the evolution of rhoA and kA can be monitored and
calibrated to preserve the astrometric performance of FGS1r.

WFPC2 9964

Dynamical Masses of White Dwarfs from Resolved Sirius-Like Binaries

In Cycle 8 we initiated a WFPC2 snapshot survey for resolved,
“Sirius-like” systems containing hot white-dwarf companions of
cooler main-sequence stars. Out of 17 systems observed to date, 8 have
been resolved with WFPC2 by using UV filters. Two of the resolved
systems—56 Persei and Zeta Cygni—have predicted or known orbital
periods short enough that dynamical masses can be determined for the
white dwarfs within reasonable times. These would thus add to the
extremely small number of white dwarfs presently having accurately and
directly measured masses. We propose to image them annually in the UV
with WFPC2. In addition, we will observe Zeta Cyg with FGS in order to
measure the absolute motion of the optical component, needed for the
mass solution. We also propose to observe Sirius itself with WFPC2
over the next 3 Cycles. The resulting astrometric data will not only
greatly improve the precision of the binary orbit and the dynamical
mass measurements for both the main-sequence and white-dwarf
components, but will also test definitively for the claimed presence
of a third body in this famous system.


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

HSTAR 9783:  Gsacq(2,3,3) results in Fine Lock Backup @ 111/0217z.  
At 111/02:16:50 GSacq(2,3,3) scheduled at 111/02:13:41 resulted in
fine lock backup (2,0,2) due to scan step limit exceeded on FGS 3.
Observations affected: NIC 30-31, ACS 114-117. Under investigation.


  • 17421-0  Genslew for proposal 10263 – slot 13 @ 110/1657z
  • 17422-0  Genslew for proposal 10263 – slot 12 @ 110/1659z
  • 17422-0  Genslew for proposal 10330 – slot 01 @ 110/1700z
  • 17423-0  Genslew for proposal 10330 – slot 02 @ 110/1702z


                           SCHEDULED     SUCCESSFUL    FAILURE TIMES 
 FGS Gsacq                08                       08 
 FGS Reacq                07                       07 
 FHST Update              16                      16 


SpaceRef staff editor.