Status Report

NASA Hubble Space Telescope Daily Report # 3509

By SpaceRef Editor
December 17, 2003
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HUBBLE SPACE TELESCOPE

DAILY REPORT # 3509

PERIOD COVERED: DOYs 346-348

OBSERVATIONS SCHEDULED

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 ideal.

STIS/CCD 9981

The Ultra Deep Field – STIS parallels

We propose to obtain slitless spectroscopy of objects in the GEMS and
GOODS area around the UDF.

WFPC2 9980

The Ultra Deep Field – WFPC2 Parallels

The ACS Ultra Deep Field {UDF} is a survey carried out by using
Director’s Discretionary time. The main science drivers are galaxy
evolution and cosmology. The primary instrument is the Advanced Camera
for Surveys but WFPC2, NICMOS, and STIS will also be used in pure
parallel mode. The data will be made public. The UDF consists of a
single ultra-deep field {410 orbits in total} within the CDF-S GOODS
area. We request a modification of the default pure parallel programs.
Rather than duplicate the redder bands which will be done much better
with ACS, we propose to observe in the near-ultraviolet F300W filter.
These data will enable study of the rest-frame ultraviolet morphology
of galaxies at 0

NIC3 9979

The Ultra Deep Field – NICMOS Parallels

This is a plan to manage the NICMOS pure parallels of the ACS Ultra
Deep Survey. We will obtain a mix of F110W and F160W images along
sight-lines within the mosaiced ACS fields of the CDF-S GOODS and GEMS
surveys, with these sight-lines enabling an examination of the space
density and morphologies of the reddest galaxies.

ACS/CCD/WFC 9978

The Ultra Deep Field with ACS

The ACS Ultra Deep Field {UDF} is a survey carried out by using
Director’s Discretionary time. The main science driver are galaxy
evolution and cosmology. The primary instrument is the Advanced Camera
for Surveys but WFPC2 and NICMOS will also be used in parallel. The
data will be made public. The UDF consists of a single ultra-deep
field {410 orbits in total} within the CDF-S GOODS area. The survey
will use four filters: F435W {55 orbits}, F606W {55 orbits}, F775W
{150 orbits}, and F850LP {150 orbits}. The F435W {B} and F606W {V}
exposures will be one magnitude deeper than the equivalent HDF
filters. The F775W {I} exposure will be 1.5 magnitude deeper than the
equivalent HDF exposure. The depth in F775W and F850LP is optimized
for searching very red objects – like z=6 galaxies – at the detection
limit of the F850LP image. The pointing will be RA{J2000}=3 32 40.0
and Decl.{J2000}=-27 48 00. These coordinates may change slightly due
to guide star availability and implementation issues. We will attempt
to include in the field both a spectroscopically confirmed z=5.8
galaxy and a spectroscopically confirmed type Ia SN at z=1.3. The
pointing avoids the gaps with the lowest effective exposure on the
Chandra ACIS image of CDFS. This basic structure of the survey
represents a consensus recommendation of a Scientific Advisory
Committee to the STScI Director Steven Beckwith. A local Working Group
is looking in detail at the implementation of the survey.

FGS 9970

The Best Brown Dwarf Yet?: FGS Astrometry of the Companion to the
Hyades Eclipsing Binary V471 Tau

The analysis of over 30 yr of 161 eclipse timings of the Hyades
eclipsing binary V471 Tauri shows the presence of a low mass tertiary
companion. A third body was found from periodic variations in the
observed arrival times of the eclipses – known as the “light time”
effect. The light time effect occurs as the relative distance {and
light travel time} changes as the eclipsing binary moves around the
barycenter of the triple system. Our analysis yields an orbital period
of P_3=30.5+/-1.6 yr, e_3=0.31+/-0.04, a semi-major axis of
a_3=11.2+/-0.4 AU, and a tertiary mass M_3 sin i_3 =0.039+/- 0.004 Mo.
For orbital inclinations >35 degrees the mass of the third body would
be below the stable hydrogen burning limit of M~0.07 Mo and thus would
be a brown dwarf. We propose HST/FGS observations of V471 Tau over the
next 3 years {2 HST orbits/year} to determine its astrometric orbit.
These HST observations, when combined with Hipparcos astrometry and
the light time orbit, will unambiguously yield the orbital inclination
and the mass of the third body. The identification of a brown dwarf in
V471 Tau will provide the first direct dynamical mass determination of
a brown dwarf with a known age {tau{Hyades}=625 Myr}, chemical
composition, and distance. In a few years {near maximum elongation},
it should be feasible to obtain IR images and spectra of this object
that will provide crucial tests of brown dwarf models.

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.

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

ACS/WFC 9860

ESSENCE: Measuring the Dark Energy Equation of State

The accelerating universe appears to be dominated by a dark energy
with a significant negative pressure. The ratio of the pressure to
density of this mysterious energy {its equation of state} is an
observable which can differentiate between the proliferating candidate
theories. We propose to estimate the dark energy equation of state by
observing Type Ia supernovae at redshifts near z=0.7 with HST in
concert with the on-going ESSENCE NOAO Survey program that is
discovering and studying supernovae between 0.3

ACS 9831

Multiplicity among brown dwarfs in the Pleiades cluster

We have compiled a sample of 32 confirmed brown dwarfs in the Pleiades
cluster. We propose to observe this sample with HST/ACS in SNAPSHOT
mode in order to search for very low mass multiple systems. Our goals
are: 1} to determine the occurrence and frequency of binary systems
among substellar objects, which hold important clues to the formation
and evolution mechanism{s} of ultracool and brown dwarfs, 2} to get an
estimate of the Initial Mass Function {IMF} at very low masses, which
is still unknown and very much needed to be corrected for binarity, 3}
to compare the distribution of multiple systems in young open clusters
and in the field.

ACS/WFC/WFPC2 9810

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 orbiting 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
with 2-3 times greater accuracy than was previously possible with
WFPC2. At 90 orbits {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 calculate the zero point of the PL relation ROBUSTLY to <4% {0.09 mag}.

ACS/WFC 9788

A Narrow-band Snapshot Survey of Nearby Galaxies

We propose to use ACS/WFC to conduct the first comprehensive HST
narrow-band {H-alpha + [N II]} imaging survey of the central regions
of nearby bulge-dominated disk {S0 to Sbc} galaxies. This survey will
cover, at high angular resolution extending over a large field, an
unprecedented number of galaxies representing many different
environments. It will have important applications for many
astrophysical problems of current interest, and it will be an
invaluable addition to the HST legacy. The observations will be
conducted in snapshot mode, drawing targets from a complete sample of
145 galaxies selected from the Palomar spectroscopic survey of nearby
galaxies. Our group will use the data for two primary applications.
First, we will search for nuclear emission-line disks suitable for
future kinematic measurements with STIS, in order to better constrain
the recently discovered relations between black hole mass and bulge
properties. Preliminary imaging of the type proposed here must be
done, sooner or later, if we are to make progress in this exciting new
field. Second, we will investigate a number of issues related to
extragalactic star formation. Specifically, we will systematically
characterize the properties of H II regions and super star clusters on
all galactic scales, from circumnuclear regions to the large-scale
disk.

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.

ACS/WFC 9765

The Dusty ISM Substructure in Nearby Spiral Galaxies

We propose an ACS V&I imaging snapshot survey of all nearby edge-on
spiral galaxies in order to measure the small scale structures in
their dust extinction down to the 10pc scale. Dust and molecular gas
are tightly coupled and therefore HST high resolution reddening maps
can reveal information about the cold ISM phase on a scale
inaccessible from the groundby any other means. We have recently
discovered a sudden change in dust lane properties using ground-based
data; all galaxies with rotation speeds in access of 120km/s show dust
lanes, but none of the slower rotators does. This transition may be
caused by a sudden change in the state of the multiphase ISM, and HST
resolution imaging is needed to fully quantify this effect. Analysis
will consist of full radiative transfer modeling of dust extinction
with realistic, fractal like substructure and power spectrum analysis
of the structure from the global to the 10pc scale. By observing a
sample of galaxies with a range in structural parameters we can
quantify how the cold ISM structure changes as function of radius,
rotation speed, local surface density, et cetera. This information is
duly needed with SIRTF soon providing a wealth of information on dust
absorption, but lacking the resolution to determine the small scale
distribution of the dust.

ACS/WFC 9744

HST Imaging of Gravitational Lenses

Gravitational lenses offer unique opportunities to study cosmology,
dark matter, galactic structure, galaxy evolution and quasar host
galaxies. They are also the only sample of galaxies selected based on
their mass rather than their luminosity or surface brightness. While
gravitational lenses can be discovered with ground-based optical and
radio observations, converting them into astrophysical tools requires
HST. HST has demonstrated that it is the only telescope that can in
each case precisely locate the lens galaxy, measure its luminosity,
color and structure, and search for lensed images of the source host
galaxy given the typical image separations of ~1”. We will obtain
ACS/WFC V and I images and NICMOS H images of 21 new lenses never
observed by HST and NICMOS H images of 16 lenses never observed by HST
in the IR. As in previous cycles, we request that the data be made
public immediately.

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.

NICMOS 9424

Externally Illuminated Circumstellar Material in the Young Nebulous
Cluster NGC 2024

HST imaging of the Orion M42 H II region has revealed circumstellar
emission and absorption regions {“proplyds”} with sizes comparable
to those expected for protoplanetary disks. Disk morphology is
directly observed in a dozen cases; disk photoevaporation is now the
working model to explain the ionized rims seen at more than 100
Trapezium cluster stars. Are the Trapezium circumstances unique?
Different cluster ages, densities, and UV radiation fields may
strongly affect proplyd characteristics. To address these questions,
we have searched for proplyds in several other young nebulous
clusters, and found that the embedded infrared cluster associated with
the NGC 2024 H II region has a large group of strong proplyd
candidates. Our WFPC2 images of the optically visible edge of the
cluster have identified an HAlpha proplyd aligned toward a B0 star.
Our VLA 3.6 cm maps show compact ionization regions coincident with 20
members of the infrared cluster – a result similar to the original VLA
proplyd discovery in M42 by Churchwell {1987}. These results strongly
indicate that infrared emission line imaging of selected cluster
members should reveal many objects similar to the those in M42. We
propose NIC2 Paschen Alpha and continuum imaging of fourteen of the
NGC 2024 compact VLA sources. Our goal is to resolve and characterize
their circumstellar structures, and compare them with those seen in
M42.

NICMOS 8790

NICMOS Post-SAA calibration – CR Persistence Part 1.

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.

WFPC2 10075

WFPC2 CYCLE 12 Intflat and Viflat Sweeps and Filter Rotation Anomaly
Monitor

Using intflat observations, this WFPC2 proposal is designed to monitor
the pixel-to-pixel flatfield response and provide a linearity check.
The intflat sequences, to be done once during the year, are similar to
those from the Cycle 11 program 9597. The images will provide a backup
database in the event of complete failure of the visflat lamp as well
as allow monitoring of the gain ratios. The sweep is a complete set of
internal flats, cycling through both shutter blades and both gains.
The linearity test consists of a series of intflats in F555W, in each
gain and each shutter. As in Cycle 11, we plan to continue to take
extra visflat, intflat, and earthflat exposures to test the
repeatability of filter wheel motions.

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.

ACS/HRC 10050

ACS Earth Flats

High signal sky flats will be obtained by observing the bright Earth
with the HRC and WFC. These observations will be used to verify the
accuracy of the flats currently used by the pipeline and will provide
a comparison with flats derived via other techniques: L-flats from
stellar observations, sky flats from stacked GO observations, and
internal flats using the calibration lamps. Weekly coronographic
monitoring is required to assess the changing position of the spots.

ACS/HRC/WFC 10042

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.

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.

STIS/CCD 10017

CCD Dark Monitor-Part 1

Monitor the darks for the STIS CCD.

STIS/CCD 10000

STIS Pure Parallel Imaging Program: Cycle 12

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

FLIGHT OPERATIONS SUMMARY:

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

HSTAR 9240: GS Acquisition (2,1,2) @ 349/00:54:41Z resulted in FL
back on FGS 2, after multiple attempts, due to SSLE on FGS 1. Prior
FHST FM Updates @ 349/00:47:50Z showed good attitude error vector,
FHST Map @ 349/01:02:57Z showed 3-axis (RSS) vehicle error ~ 12.00
arcsec. Under investigation.

COMPLETED OPS REQs: NONE

OPS NOTES EXECUTED: NONE

                            SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq                25                        25
FGS REacq                24                        24
FHST Update              29                        29
LOSS of LOCK

SpaceRef staff editor.