Status Report

NASA Hubble Space Telescope Daily Report # 3490

By SpaceRef Editor
November 19, 2003
Filed under , ,





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 9792

Uncovering the CV population in M15: a deep, time-resolved, far-UV
survey of the cluster core

We propose to carry out a deep, far-ultraviolet {FUV}, time-resolved
for faint cataclysmic variables {CVs} and other dynamically-formed
objects in the globular cluster {GC} M15. We will use the ACS/SBC to
carry out 6 epochs of FUV imaging of this cluster in a single filter,
and will use two additional visits to obtain images in other FUV and
NUV filters. Since crowding is not a problem in the FUV, this will
yield time-resolved FUV photometry of all blue objects in the cluster
core. Our CV census will be both deep enough to be essentially
complete and “broad” enough to involve all of the following CV
characteristics: {1} UV brightness; {2} blue FUV spectral shape; {3}
strong CIV and HeII emission; {4} short time-scale {$sim$ minutes}
variability {flickering, WD spin}; {6} intermediate time-scale {$sim$
hours} variability {orbital variations}; {7} long time-scale {$sim$
weeks} variability {dwarf nova eruptions}. We will thus find the CV
population in M15, if it exists. In addition, our survey will detect
numerous blue stragglers and hot white dwarfs, as well as any other
blue objects near the core. Finally, our photometry will yield
high-quality FUV light curves of the two low-mass x-ray binaries in


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.


Probing the Dynamics and Shock Physics of the Cas A Supernova Remnant

Cassiopeia A {Cas A; SN 1680} is the youngest known and closest
example of an oxygen-rich, core-collapse supernova remnant. A two-year
WFPC2 survey of part of the remnant yielded many new insights
including realization of the stunning amount of fine-scale detail
present in the ejecta, and the first precise location of the reverse
shock front in the main shell via rapid emission and structural
changes visible over 2 yrs. In addition, these data revealed over 100
new ejecta knots located out ahead of the forward blast wave in a
small region where only a handful were known from ground-based images.
We propose a follow-up survey program aimed at obtaining hi-res images
of the entire remnant in the ejecta’s four major emission lines. A
separate set of ACS and NIC3 [Si VI] images of the NW reverse shock
filaments will be taken 3-4 months following the main Cycle 12 survey
images. These will allow us to the trace individual ejecta knot
deceleration dynamics, excitation, and evolution during reverse shock
passage. Analysis of the emission line fluxes will make use of custom
shock models generated by us for Cas A. These data will also provide
data on outer knot chemistry and expansion asymmetries particularly in
regard to the collimation of the NE and SW jets of O, Si, Ca-rich
ejecta. A major aim of this program is to acquire a superb two-year
image database covering the entire remnant to allow a detailed shock
physics and dynamics study.

FGS 9879

An Astrometric Calibration of the Cepheid Period-Luminosity Relation

We propose to measure the parallaxes of 10 Galactic Cepheid variables.
There is no other instrument on or off the earth that can consistently
deliver HST FGS level of precision for critical parallaxes. 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.

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.

NIC1/NIC2/NIC3 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

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.

S/C/NIC3 9832

A Search for Water Vapor in the Atmosphere of an Extrasolar Planet

We propose to search for evidence of water vapor in the transmission
spectrum of the transiting planet of HD 209458. A successful detection
would not only establish the presence of this important atmospheric
constituent, but would also constrain other key properties of this
close-in, Jupiter-sized planet. Specifically, relating the absorption
caused by water to that already observed from atomic sodium would help
establish the height of the atmosphere’s uppermost cloud layer {if
any}. Also, the abundance of water will provide information about that
of oxygen, and by extension, that of all heavy elements. To make this
measurement, we propose a doubly-differential procedure in which we
will use NICMOS in spectroscopic mode to detect the small spectral
changes that occur during planetary transits, and that result from
absorption of starlight as it passes through the outer parts of the
planet’s atmosphere. We search for water because it is expected to
produce by far the strongest spectrum features within the wavelength
range accessible to HST.

STIS/CCD 10000

STIS Pure Parallel Imaging Program: Cycle 12

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

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.

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 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 10082

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans

WFPC2 9729

Probing the nature of Type Ia SNe through HST astrometry

Type Ia supernovae are of key importance in cosmology. Empirical
relations allow their use as cosmological standard candles. The
generally accepted picture is that the exploding star is a C+O white
dwarf which accretes matter from a companion in a binary system.
However, the nature of the companion is still unknown. It could either
be another WD, or be a giant, subgiant, or main-sequence star.
Calculations have shown that it is possible to distinguish among those
possibilities by the effect that the supernova explosion has on the
companion star. We propose to identify the companion star of the two
historical well-known SNeIa through ACS imaging of the targets
complemented by WFPC2 observations. A radial-velocity study of the
stars in those two Galactic SNeIa has been done from ground-based
facilities. To obtain the full motion vector of those stars, we plan
to use ACS for high-resolution astrometry in two different epochs.
That should allow to detect motion imparted during the explosion in
the d ir ection perpendicular to the line of sight, down to a level of
a few milliarcsecs/yr.

WFPC2 9968

Fundamental properties of L-type dwarfs in binaries

We propose to characterize the physical properties of eight L-dwarfs
in four binary systems. Our goal is to obtain astrometric, photometric
and spectroscopic measurements of each component that will yield basic
information on their atmospheric and dynamical properties. The high
angular resolution of HST is essential because all these systems have
angular separations $le$0.5 arcsec. They do not have bright enough
stars nearby that can be used for natural guide adaptive optics in
ground-based telescopes. In Cycles~10 and 11 we propose to obtain
WFPC2 and STIS data, allowing the determination of parallax, proper
motion, position and spectral type for each component. In Cycle 12 we
plan to obtain additional WFPC2 images for follow-up of the orbital
motion and refinement of parallax and proper motion. We will also
monitor possible intrinsic photometric variability in two filters
{F675W and F814W}. The STIS observations will provide spectral types,
gravity sensitive indicators, and chromospheric activity {H$_ lpha$
emission} for each component. These 4 systems will constitute
benchmarks for determining dynamical masses of L dwarfs, and inferring
the age-mass-spectral type relationship of this new spectral class.


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


911-0 Limit Management During WFPC2 Decontamination (M001) @ 317/14:52z
1160-2 Default Configuration for TMDIAG’s @ 317/19:02z

                             SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq                 06                        06
FGS REacq                 10                        10
FHST Update               08                        08


SpaceRef staff editor.