Status Report

NASA Hubble Space Telescope Daily Report # 3397

By SpaceRef Editor
July 3, 2003
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NICMOS Post-SAA calibration – CR Persistence Part 2

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.

STIS 9359

The Old Star CS 31082-001, the Age of the Universe, and the Nature of the

We propose to observe the newly discovered r-process-element enhanced
star, CS 31082-001 {Fe/H ~ -2.9}, in order to determine abundances of
the heaviest stable elements, using absorption lines that are only
reachable in the near UV. This star is the only halo star for which a
uranium detection has been reported, and for which the U/Th
chronometer has been used to specify an age limit. In order to improve
the accuracy of the age determination from U/Th we require abundance
estimates of the daughter nuclides –Pb & Bi– for which only upper
limits have been obtained from ground-based observations. Such
estimates will provide crucial constraints on the initial production
ratio of U/Th, resulting in a more strict lower limit on the age of
this star’s progenitor, hence on the age of the Universe. Measurements
of 3rd-peak neutron-capture elements, such as Pt, Os, Ir, and Au, all
with lines in the 2400-3100 Angstrom range, will expand our knowledge
of element synthesis in the early Galaxy. Our recent ESO-VLT data
indicate that the neutron-capture elements in this star exhibit
different enhancements as compared with the previously known “
r-process star” CS 22892-052, an apparent anomaly that must be
resolved. CS 31082-001 is the ideal HST target in its class — it is
4-times brighter than CS 22892-052, and less affected by molecular
line blending. Consequently, these HST data will become the reference
in all future studies of similar stars.

ACS/HRC 9379

Near Ultraviolet Imaging of Seyfert Galaxies: Understanding the
Starburst-AGN Connection

We propose a near-UV snapshot survey of 101 Seyfert galaxies using
ACS/HRC and the filter F330W, a configuration which is optimal to
detect faint star forming regions around their nuclei. These images
will complement optical and near-IR images available in the HST
archive, thus providing a panchromatic atlas of the inner regions of
active galaxies, which we will use to study the starburst-AGN
connection. The main goals of this proposal are: {1} Determine the
frequency of circumnuclear starbursts in Seyferts, down to levels
which cannot be observed from the ground; {2} characterize the
observational {fluxes, colors, structure, sizes} and intrinsic
{luminosities, masses, ages, global star-formation rate} properties of
these clusters; {3} derive the luminosity functions of young star
clusters around the nucleus of Seyferts and compare these results with
those from normal and starburst galaxies to determine their survival
rate close to the AGN; {4} address questions about the relation
between AGNs and starbursts, like the possible connection between the
masses and luminosities of black holes and starbursts, and the
implications for the evolution of the black holes and their host
galaxy bulges. By adding UV images to the existing optical and near-IR
ones, this project will create an extremely valuable database for
astronomers with a broad range of scientific interests, from the
properties of the AGN to the properties of their host galaxies.

ACS 9454

The Nature of the UV Continuum in LINERs: A Variability Test

LINERs may be the most common AGNs, and the signposts of accretion
onto the massive black holes present in most galaxies. However, the
LINER spectrum is the result of UV excitation, and, in at least some
LINERs, a nuclear cluster of hot stars, rather than an AGN, dominates
the energetics in the UV. Thus, it is still unknown if the UV
continuum, or the optical emission lines it excites, have anything to
do with an AGN. The demographics and accretion physics of
low-luminosity AGNs hinge on this question. We propose to search for
variability in a sample of 17 LINERs with compact UV nuclei.
Variability can reveal an AGN component in the UV continuum, even when
its light is not dominant. We will test systematically the handful of
non-definitive reports of UV variability, and potentially quantify the
AGN contribution to the UV emission. Variability in all or most
objects will be strong evidence that LINERs mark dormant AGNs in most
galaxies. Alternatively, a general null detection of variability will
suggest that, even in LINERs with additional AGN signatures, the UV
continuum is stellar in origin. Contemporaneous monitoring with the
VLA/VLBA of 11 objects which have radio cores {five of which we
already know are radio-variable} will reveal the relations between UV
and radio variations. The UV-variable objects will be targeted for
future, better-sampled, monitoring.

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 interval. 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
including 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 cosmological
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 9482

ACS Pure Parallel Lyman-Alpha Emission Survey {APPLES}

Ly-alpha line emission is an efficient tool for identifying young
galaxies at high redshift, because it is strong in galaxies with young
stars and little or no dust — properties expected in galaxies
undergoing their first burst of star- formation. Slitless spectroscopy
with the ACS Wide-Field Camera and G800L grism allows an unmatched
search efficiency for such objects over the uninterrupted range 4 <~ z <~ 7. We propose the ACS Pure Parallel Ly-alpha Emission Survey {``APPLES''}, to exploit this unique HST capability and so obtain the largest and most uniform sample of high redshift Ly-alpha emitters yet. Parallel observations will allow this survey to be conducted with minimal impact on HST resources, and we will place reduced images and extracted spectra in the public domain within three months of observation. We aim to find ~ 1000 Ly-alpha emitters, 5 times the biggest current sample of Ly-alpha emitters. This unprecedented sample will provide robust statistics on the populations and evolution of Ly-alpha emitters between redshifts 4--7; a robust measurement of the reionization redshift completely independent of the Gunn-Peterson trough; spatial clustering information for Ly-alpha emitters which would let us probe their bias function and hence halo mass as a function of redshift; many galaxies at redshift exceeding 6; and lower redshift serendipitous discoveries.


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. Such a search has
several advantages over field surveys, including greater sensitivity
to VLM objects and the availability of precise parallaxes from which
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 search 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 will firmly establish the LF for VLM companions at separations
of 1-1000 AU and the multiplicity fraction of all stars within 10 pc.

WFPC2 9595


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

STIS 9606

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS 9608

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.

ACS 9674

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 9708

STIS Pure Parallel Imaging Program: Cycle 11

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

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.


The Role of Groups in the Evolution of Galaxies at Intermediate Redshifts

Groups are the most common environment experienced by galaxies, yet
they remain the least studied. The tidal fields and dynamical friction
encountered by galaxies in groups probably holds the key to
understanding the role of environment in driving the evolution of
galaxies since z ~ 1. To study the evolution of galaxies in the group
environment, we propose the first unbiased HST study of groups at
moderate redshifts. Unlike previous HST group samples, that relied on
radio or X-ray properties, our kinematically selected sample is drawn
from a large redshift survey and is not biased towards unusually dense
groups. HST imaging is essential to determine the morphology of
galaxies in these systems and contrast this with the properties of
galaxies in denser and more evolved groups and rich clusters at these
epochs. HST data are also required to adequately compare the
properties of groups at intermediate redshifts with local group
samples derived from the 2df and Sloan surveys. We will combine the
HST images with deep ground-based observations to study how
morphologies and stellar populations of galaxies in groups have
evolved in time. These observations are key to understanding the
decline in the volume averaged star formation rate in the universe.

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.


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

HSTAR 9070: After review of M_SA174N TC log file on PTAS, found GS
Re-acquisition @ 2003.175/01:57Z took two attempts for FGS 2R to
achieve FL. No observations should have been impacted as the
re-acquisition was ultimately successful. During the first FL attempt
on FGS 2R, the Stop flag came up ~ 9 seconds into the FL walk down,
possibly indicating the FGS had walked off the GS. Under

HSTAR 9071: After review of M_SA174N TC log file on PTAS, found GS
Re-acquisition @ 2003.180/07:40Z took two attempts to achieve FL on
FGS 3. No observations should have been impacted as the
re-acquisition was ultimately successful. During the first FL attempt
on FGS 2R, the SSLE and Stop flag came us during the FL walk down.
Under investigation.

HSTAR 9072: GS Re-acquisition (1,3,3) @ 184/01:19:49Z required three
attempts to achieve FL on FGS 3 due to SSLE. This is believed to have
caused mnemonics OCSTDFBX (CS TDF Bailout status) to flag “Bailout”.
GS Re-acquisition (1,3,3) @ 184/02:55:52Z showed two scan step limit
flags @ 184/02:58:28Z and 184/02:59:37Z, GS re-acquisition was
ultimately successful on third try. Re-acquisition @ 184/04:31:54Z
did not produce any scan step limit flags. Re-acquisition @
184/06:07:57Z occurred while vehicle was LOS, no data available until
engineering recorder playback. Under investigation.


1127-0 Limit Adjustment for CCC K51 to Level 5 Change @ 183/1356z
1118-0 Resubmit: Battery 2 Capacity Test limits @ 183/1506z

FGS GSacq 11 11
FGS REacq 07 07
FHST Update 22 22


SpaceRef staff editor.