Status Report

HST Daily Report # 3287

By SpaceRef Editor
January 28, 2002
Filed under , ,





ACS 9472

A Snapshot Survey for Gravitational Lenses among z >= 4.0 Quasars

Over the last few years, the Sloan Digital Sky Survey has revolutionized the
study of high-redshift quasars by discovering over 200 objects with redshift
greater than 4.0, more than doubling the number known in this redshift
The sample includes eight of the ten highest redshift quasars known. We propose
a snapshot imaging survey of a well-defined sample of 250 z > 4.0 quasars in
order to find objects which are gravitationally lensed. Lensing models
magnification bias predict that at least 4% of quasars in a flux-limited sample
at z > 4 will be multiply lensed. Therefore this survey should find of order 10
lensed quasars at high redshift; only one gravitationally lensed quasar is
currently known at z > 4. This survey will provide by far the best sample to
date of high-redshift gravitational lenses. The observed fraction of lenses can
put strong constraints on cosmological models, in particular on the
constant Lambda. In addition, magnification bias can significantly bias
estimates of the luminosity function of quasars and the evolution thereof; this
work will constrain how important an effect this is, and thereby give us a
better understanding of the evolution of quasars and black holes at early
epochs, as well as constrain models for black hole formation.

ACS 9673

CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
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 9650

CCD Hot Pixel Annealing

Hot pixel annealing will be performed once every 4 weeks. The CCD TECs will be
turned off and heaters will be activated to bring the WFC detector temperature
to about +10C. The HRC temperature will reach about 30C.This state will be held
for approximately 24 hours, after which the heaters are turned off, the TECs
turned on, and the CCDs returned to normal operating condition. To assess the
effectiveness of this procedure, a bias and two dark images will be taken
and after the annealing procedure for both WFC and HRC.

ACS 9426

Jupiter’s Ring Plane Crossing of 2002-2003

Jupiter’s ring system consists of three components: the main band, the
vertically-extended inner halo and the exterior gossamer rings. Each component
illustrates aspects of dust dynamics within Jupiter’s inclined magnetic field
and its strong plasma environment. We will image all three components with ACS
during an unusual, extended period of edge-on viewing, December 2002 through
February 2003. For faint planetary rings, this geometry improves the
signal-to-noise ratio considerably and permits an unambiguous decoupling of
radial and vertical structure. Although the Jovian rings have been examined by
four spacecraft and from the ground, we are still lacking in a systematic
set of
data that can distinguish between the ring’s prominent dust population and its
embedded macroscopic source bodies. We also do not know the size
distribution of
dust with sufficient accuracy to test rival theories of ring origin.
Observations of the system at a range of wavelengths and phase angles with ACS
will finally make this determination possible. Coordinated observations at the
W. M. Keck Telescope will extend our wavelength coverage well into the IR.

ACS 9656

Stability of the ACS CCD: geometry, flat fielding, photometry

A moderately crowded stellar field, located ~6′ West of the centre of the
cluster 47 Tuc, is observed repeatedly {every three weeks with the WFC, every
other month with the HRC} in various filters, spending 1 orbit per epoch.
Different filters will be used every time, so that over the course of the year
all filters will have been employed at least twice. The most common filters
be checked more frequently. The same field has been observed in the course of
the SMOV phase and the positions and magnitudes of the most prominent stars
been accurately measured. Although the field is neither a proper
astrometric nor
a proper photometric standard one, the positions and magnitudes of the objects
in it can be used to monitor any local and large scale variations in the
platescale and sensitivity of the detectors. It should be noted that for the
filters which have already been used during the SMOV phase it will be
to take one single image, without CR-SPLIT, since the exposure time is always
short {20-30 sec} and there will be so many stars that the few of them
which are
affected by cosmic rays can be discarded as outliers in the photometry. For
narrow and medium band filters not exercised on this target in the SMOV phase,
however, a baseline will have to be set. This expenditure of time will apply to
the current cycle only. At variance with the approach used in SMOV, there is no
need for large telescope slews to place the same objects on opposite sides of
the detectors, thence allowing the programme to remain compact and efficient.
All exposure level parameters are set to their default values, except for the
amplifier gain of the WFC exposures in the F606W band, which will be collected
with the gain value of 2 for the WFC for compatibility with the SMOV
observations. The exposure time is typically 30 seconds for the WFC, 60 sec for
the HRC. No attempt will be made to attain a predefined or the same orientation
on the sky amongst different epochs. Typically, for the WFC, five exposures
be accommodated in one orbit. For the HRC, about 10 exposures can be fitted
within one orbit

ACS 9401

The ACS Virgo Cluster Survey

We propose the most comprehensive imaging survey to date of low-redshift,
early-type galaxies. Our goal is to exploit the exceptional imaging
of the ACS by acquiring deep images — in the SDSS g^ and z^ bandpasses
— for
163 E, S0, dE, dE, N and dS0 galaxies in Virgo, the nearest rich cluster. This
extraordinary dataset would likely constitute one of the principal legacies of
HST, and would have widespread applications for many diverse areas of
astrophysics. Our immediate scientific objectives are threefold: {1} measure
metallicities, ages and radii for the many thousands of globular clusters {GCs}
in these galaxies, and use this information to derive the protogalactic mass
spectrum of each galaxy; {2} measure the central luminosity and color
profile of
each galaxy, and use this information to carry out a completely independent
of the merging hierarchy inferred from the GCs, with the aid of N-body codes
that simulate the merger of galaxies containing massive black holes; and {3}
calibrate the z^ -band SBF method, measure Virgo’s 3-D structure, and carry out
the definitive study of the GC luminosity function’s precision as a standard
candle. Our proposed Virgo Cluster Survey will yield a database of
depth, precision and uniformity, and will enable us to study the record of
galaxy and cluster formation in a level of detail which will never be possible
with more distant systems.

ACS 9352

The Deceleration Test from Treasury Type Ia Supernovae at Redshifts 1.2 to 1.6

Type Ia supernovae {SNe Ia} provide the only direct evidence for an
universe, an extraordinary result that needs a rigorous test. The case for
cosmic acceleration rests on the observation that SNe Ia at z ~ 0.5 are ~ 0.25
mag fainter than they would be in a universe without acceleration. A powerful
and straightforward way to assess the reliability of the SN Ia measurement and
the conceptual framework of its interpretation is to look for cosmic
deceleration at z >= 1. This would be a clear signature of a mixed dark-matter
and dark-energy universe. Systematic errors in the SN Ia result attributed to
grey dust or cosmic evolution of the SN Ia peak luminosity would not show this
change of sign. We have demonstrated proof of this concept with a single SN Ia,
SN 1997ff at z = 1.7, found and followed by HST. The results suggest an early
epoch of deceleration, but this is too important a conclusion to rest on just
one object. Here we propose to use HST for observations of six SNe Ia in the
range 1.2 <= z <= 1.6, that will be discovered as a byproduct from proposed Treasury programs for high-latitude ACS surveys. Six objects will provide a much firmer foundation for a conclusion that touches on important questions of fundamental physics.

ACS/WFC 9433

The Size Distribution of Kuiper Belt Bodies

The Kuiper Belt is a population of remnant planetesimals from the formation of
the Solar System. Since the planetesimals in extrasolar systems are too
faint to
see with present or planned telescopes, the Kuiper Belt is our best chance to
test models of accretional/collisional evolution against observations. Current
ground-based observations of Kuiper Belt Objects {KBOs} are consistent with a
pure power law size distribution N{D}propto D^-q, q~4.3. Current accretion
models predict a break to a shallower slope q=3.5 for objects of diameter
D<~100 km. We will conduct a survey of 6 ACS/WFC fields to detect KBOs with R<28.5, and diameters as small as D~10 km. The number of KBOs at these small sizes, unmeasurable from the ground, will test the existence of the predicted break with 95% confidence---we expect between 12 and 50 detections. A census of small KBOs is also important in confirming the idea that short-period comets are errant KBOs. With HST and ground- based followup, we can determine orbital parameters for the detected KBOs, and search for dynamical populations which may be deficient in D>100 km KBOs and hence not yet detected. In particular, we
determine whether the current absence of objects with perihelia beyond 50 AU is
due to a truncation of the protoplanetary disk at some point in Solar System
history, or just a failure to accrete D>150 km objects.

ACS/WFPC2 9481

Pure Parallel Near-UV Observations with WFPC2 within High-Latitude ACS Survey

In anticipation of the allocation of ACS high-latitude imaging survey{s}, we
request a modification of the default pure parallel program for those WFPC2
parallels that fall within the ACS survey field. Rather than duplicate the red
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

FGS 9348

The Distances to AM CVn stars

We propose to determine the parallaxes and proper motions of the five brightest
of the seven known AM CVn systems using the HST Fine Guidance Sensors. AM CVn
systems are binaries where mass is transferred from a completely
hydrogen-deficient, degenerate mass donor to a white dwarf primary through a
helium accretion disk. A better understanding of these systems is crucial for a
number of reasons:, to study the late stages of binary evolution, to study the
effect of chemical composition on the physics of accretion discs; , o to
estimate their contribution to the Supernovae Ia rate and , to estimate their
contribution to the gravitational radiation background. All these studies rely
critically on a determination of the distances to the currently known systems.
With brightnesses in the range 13

HST 9382

A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS QSO MgII-FeII Systems.

We have searched the first public release of SDSS QSO spectra for low-z
{z<1.65} metal absorption lines and found over 200 large rest equivalent width MgII-FeII systems. Previously, we empirically showed that such systems are good tracers of large neutral gas columns, with ~50% being classical damped Lyman alpha {DLA} systems {N_HI>=2*10^20 cm^-2}. Here we propose to follow up a well-defined
subset of 79 of them to search for DLAs with 0.47


Completing A Near-Infrared Search for Very Low Mass Companions to Stars within
10 pc of the Sun

Most stars are fainter and less massive than the Sun. Nevertheless, our
knowledge of very low mass {VLM} red dwarfs and their brown dwarf cousins is
quite limited. Unknown are the true luminosity function {LF}, multiplicity
fraction, mass function, and mass-luminosity relation for red and brown dwarfs,
though they dominate the Galaxy in both numbers and total mass. The best way to
constrain these relations is a search for faint companions to nearby stars.
a search has several advantages over field surveys, including greater
sensitivity to VLM objects and the availability of precise parallaxes from
luminosities and masses can be derived. We propose to complete our four-filter
NICMOS snapshot search for companions to stars within 10 pc. With a 10 sigma
detection limit of M_J ~ 20 at 10 pc, we can detect companions between 10 and
100 AU that are at least 9 mag fainter than the empirical end of the main
sequence and at least 6.5 mag fainter than the brown dwarf Gl 229B. When
completed, our search will be the largest, most sensitive, volume-limited
for VLM companions ever undertaken. Our four-filter search will permit
unambiguous identification of VLM-companion candidates for follow-up
observation. Together with IR speckle and deep imaging surveys, our program
firmly establish the LF for VLM companions at separations of 1-1000 AU and the
multiplicity fraction of all stars within 10 pc.


Infrared Photometry of a Statistically Significant Sample of KBOs

While the discovery rate of Kuiper Belt objects is accelerating, the physical
study of this new region of the solar system has been slowed by a lack of basic
astrophysical data. Photometric observations of the majority of the more than
400 known KBOs and Centaurs are rudimentary and incomplete, particularly in the
infrared. The multicolor optical-infrared photometry that exists for a small
subset of KBOs often shows significant discrepancies between observations by
different observers. Their intrinsic faintness puts them at the practical
of ground-based systems. In July 2001 we began what will be the largest uniform
sample of optical photometry of KBOs with a WFPC2 SNAPSHOT program that will
perform accurate photometry at V, R, and I on a sample of up to 150 targets. We
seek to greatly enhance the value of this survey by obtaining J and H
on the same sample using NICMOS. Combined optical and infrared broad band
photometry is a far more powerful tool for physical studies than is either
alone. Our sample includes objects that will be observed at thermal infrared
wavelengths by SIRTF and will be used with those data to derive the first
accurate diameters, albedos, and surface properties for a large sample of


NICMOS Parallel Thermal Background

NICMOS Camera 2 pure parallel exposures in the F222M and F237M filters to
establish the stability of the HST+NCS+Instrument thermal emission. This data
will be compared against the already available Camera 3 measurements in F222M
which show an increased thermal background.


NICMOS Post-SAA calibration – CR Persistence Part 1.

A new procedure proposed to alleviate the CR-persistence problem of NICMOS.
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
darks will be non-standard reference files available to users with a USEAFTER
date/time mark.


Paschen-alpha Imaging of a SIRTF-Selected Nearby Galaxy Sample

We propose to carry out a NICMOS snapshot survey in the Paschen-alpha {PAlpha}
emission line and H-band of the sample of galaxies being observed at 3.5 — 160
microns as part of SIRTF Nearby Galaxies Survey {SINGS} and a related
time survey of starburst galaxies. The PAlpha images, accessible only from HST,
will be combined with groundbased HAlpha imaging to measure the extinction in
the star-forming centers of these galaxies, and obtain robust, extinction-
corrected maps of the massive star formation rate {SFR}. The PAlpha data by
themselves will provide reliable `extinction- free’ SFRs, and a
cross-calibration of the {dust–affected} HAlpha– and UV–based SFRs. The
PAlpha–based SFR measurements will extend the SFR-vs.-gas density law
{Schmidt–law} to surface densities at least 30 times higher than what is
accessible using HAlpha–based SFR measurements alone, bridging the gap between
normal galaxies and IR–luminous starbursts. Furthermore, the combination
of the
HST PAlpha images with the SIRTF images and spectra, as well as ancillary
ground–based UBVRIJHK images and GALEX UV images being obtained as part of the
SINGS project, will provide a definitive study of the radiative transfer of
starlight and dust heating in star–forming galaxies. The processed NICMOS
images will be incorporated into the public SINGS Legacy Data Archive, to
scores of follow-up studies by the astronomical community at large.


The NICMOS Parallel Observing Program

We propose to manage the default set of pure parallels with NICMOS. Our
experience with both our GO NICMOS parallel program and the public parallel
NICMOS programs in cycle 7 prepared us to make optimal use of the parallel
opportunities. The NICMOS G141 grism remains the most powerful survey tool for
HAlpha emission-line galaxies at cosmologically interesting redshifts. It is
particularly well suited to addressing two key uncertainties regarding the
global history of star formation: the peak rate of star formation in the
relatively unexplored but critical 1<= z <= 2 epoch, and the amount of star formation missing from UV continuum-based estimates due to high extinction. Our proposed deep G141 exposures will increase the sample of known HAlpha emission- line objects at z ~ 1.3 by roughly an order of magnitude. We will also obtain a mix of F110W and F160W images along random sight-lines to examine the space density and morphologies of the reddest galaxies. The nature of the extremely red galaxies remains unclear and our program of imaging and grism spectroscopy provides unique information regarding both the incidence of obscured star bursts and the build up of stellar mass at intermediate redshifts. In addition to carrying out the parallel program we will populate a public database with calibrated spectra and images, and provide limited ground- based optical and near-IR data for the deepest parallel fields.

STIS 9607

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

STIS 9605

CCD Dark Monitor-Part 1

Monitor the darks for the STIS CCD

STIS 8659

High Resolution Spectrum of the Venus Lyman-Alpha Line Profile

We propose to record a single high spectral resolution observation of the Venus
Lyman-alpha line, while HST is within Earth shadow and Venus is at 47.1 degrees
solar elongation, with a supporting observation of the Lyman-alpha geocorona
outside the exclusion zone {50 degrees}. This Lyman-alpha line profile will be
compared with emergent line profiles from Venus thermosphere radiative transfer
models to assess the energetics and contributions from supra-thermal sources of
hydrogen, a long-standing issue in Venus aeronomy. This information will
understanding of the pathways of hydrogen escape from Venus and constrain
of Venus climate evolution. The line profile will be used to assess the
abundance of deuterium in the Venus atmosphere, a quantity with great
to atmospheric evolution models. The HST STIS instrument is the only instrument
capable of making these far UV observations with sufficient spectral resolution
to address the details of hydrogen energetics in the Venus thermosphere and
exosphere. HST previously observed Venus with Esposito as PI {P4518 and

STIS 9625

STIS NUV-MAMA Cycle 11 Flats

This program will obtain NUV-MAMA observations of the STIS internal Deuterium
lamp to construct an NUV flat applicable to all NUV modes

STIS 9633

STIS parallel archive proposal – Nearby Galaxies – Imaging and Spectroscopy

Using parallel opportunities with STIS which were not allocated by the TAC, we
propose to obtain deep STIS imagery with both the Clear {50CCD} and Long-Pass
{F28X50LP} filters in order to make color-magnitude diagrams and luminosity
functions for nearby galaxies. For local group galaxies, we also include G750L
slitless spectroscopy to search for e.g., Carbon stars, late M giants and
stars. This survey will be useful to study the star formation histories,
chemical evolution, and distances to these galaxies. These data will be placed
immediately into the Hubble Data Archive.

STIS 9706

STIS Pure Parallel Imaging Program: Cycle 10

This is the default archival pure parallel program for STIS during cycle 10.


Closing in on the Hydrogen Reionization Edge of the Universe.

The Space Telescope Imaging Spectrograph (CCD) was used in parallel constrain
the Hydrogen reionization edge in emission that marks the transition from a
neutral to a fully ionized IGM at a predicted redshifts.


Towards a global understanding of accretion physics –, Clues from an UV
spectroscopic survey of cataclysmic variables

Accretion inflows and outflows are fundamental phenomena in a wide variety of
astrophysical environments, such as Young Stellar Objects, galactic binaries,
and AGN. Observationally, cataclysmic variables {CVs} are particularly well
suited for the study of accretion processes. We propose to carry out a STIS UV
spectroscopic snapshot survey of CVs that fully exploits the diagnostic
potential of these objects for our understanding of accretion physics. This
survey will provide an homogenous database of accretion disc and wind outflow
spectra covering a wide range of mass transfer rates and binary
inclinations. We
will analyse these spectra with state-of-the-art accretion disc model spectra
{SYNDISK}, testing our current knowledge of the accretion disc structure, and,
thereby, providing new insight into the so far not well understood process of
viscous dissipation. We will use our parameterised wind model PYTHON for the
analysis of the radiation driven accretion disc wind spectra, assessing the
fundamental question whether the mass loss rate correlates with the disc
luminosity. In addition, our survey data will identify a number of systems in
which the white dwarf significantly contributes to the UV flux, permitting an
analysis of the impact of mass accretion on the evolution of these compact
stars. This survey will at least double, if not triple, the number of
high-quality accretion disc / wind outflow / accreting white dwarf spectra, and
we waive our proprietary rights to permit a timely use of this database.

WFPC2 9699

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans.

WFPC2 9676

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 9634

POMS Test Proposal: WFII targeted parallel archive proposal

The parallel opportunities available with WFPC2 in the neighborhood of bright
galaxies are treated in a slightly different way from the normal pure
Local Group galaxies offer the opportunity for a closer look at young stellar
populations. Narrow-band images in F656N can be used both to identify young
stars via their emission lines, and to map the gas distribution in star-forming
regions. Thus, the filter F656N is added to the four standard filters. Near
distant galaxies, up to about 10 Mpc, we can map the population of globular
clusters; for this purpose, F300W is less useful, and only F450W, F606W, and
F814W will be used.

WFPC2 9594


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

WFPC2 9599

WFPC2 Cycle 11 UV Earth Flats

Monitor flat field stability. This proposal obtains sequences of earth streak
flats to improve the quality of pipeline flat fields for the WFPC2 UV filter
set. These Earth flats will complement the UV earth flat data obtained during
cycles 8-10.

WFPC2 9589

WFPC2 Decontaminations and Associated Observations Pt. 1/3

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 check.


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

16894-0 – Venus Observation Patch @ 026/1107z
16885-0 – Configure DIU Reader for GYRO#3 Motor Current Sampling @ 026/1116z


                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq              24                       24
FGS REacq              21                       21
FHST Update            48                       48

The science SMS was successfully intercepted at 024/1200z. WFPC/2 science
resumed at
024/1250z with the rest of the SIs following throughout the day:

024/1250z – WFPC/2 (Proposal 9589)
024/1517z – NICMOS (Proposal 9386)
024/1615z – ACS (Proposal 9352)
024/2103z – STIS (Proposal 9706)

Mission Operations support of the Venus observation began with the
successful execution of
Ops Request #16894 (Venus Observation Patch) at 026/05:56 GMT to install
specific changes
to the onboard SSM486 FSW Version 2.2 Release A RAM. The safemode macro
definitions for
Inertial Hold were patched to change the safemode response from Inertial
Hold to Software
Sunpoint because the observation requires HST to be pointed close to the
sun while in the
earth’s shadow. The sunpoint angle limit was also changed from 46 deg to
42 deg to provide
a margin for the expected 46 deg at the closest approach. The guide star
pair acquisition
(GSAcq 2,3,2) at Venus (+5 deg), the single guide star acquisition (GSAcq
1,0,1) at Venus,
the guide star pair acquisition (GSAcq 1,3,1) at Venus (+5 deg), and the
final guide star
pair acquisition (GSAcq 2,1,2) away from Venus were all
successful. Telemetry indicated
nominal performance for all PCS and FGS hardware during vehicle slew and
observation periods.
Following the completion of the Venus Observation at 026/11:06 GMT, Ops
Request #16894 was
successfully executed to back-out the Venus observation patches to revert
back to the
original version of the SSM486 FSW.

SpaceRef staff editor.