Status Report

NASA Hubble Space Telescope Daily Report # 3493

By SpaceRef Editor
November 21, 2003
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ACS/HRC 9989

Starburst Galaxies and Their Population of Super Star Clusters

Starbursts are ideally suited to study the evolution of high mass
stars, the physics of star formation, and the chemical enrichment of
the intergalactic medium {IGM}. Starbursts efficiently form Super Star
Clusters {SSC} which may be young protoglobular clusters. High
resolution imaging will address two important outstanding issues: 1}
how long starbursts last and 2} whether SSCs are indeed young globular
clusters. The duration of starbursts is important because: {1} it
determines how efficiently a starburst can heat and enrich the IGM;
{2} the duration combined with estimates of the fraction of galaxies
which host starbursts yields the total number of starbursts a galaxy
can suffer. Finally, since local starbursts are analogs to high-z
galaxies, the results have implications on the initial formation
timescale of galaxies. Starburst duration will be determined from HRC
imaging of two face-on starburst galaxies rich in SSCs. The UV to
optical colors of the SSCs, which represent single burst chronometers,
will yield their reddening and ages. The range of ages gives the
starburst duration. The nature of SSCs will be investigated by imaging
four of the nearest starbursts in 3 bands. By comparing the sizes of
their SSCs at different wavelengths we will address the issue of
whether SSCs suffer from early mass segregation. Without some mass
segregation the velocity dispersions of SSCs suggest that they are
deficient in low mass stars, and hence may not represent true
proto-globular clusters.

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.


A test of the foreground proximity effect at z=1.2

The diffuse UV background flux J is a crucial component for
cosmological evolution models, though few determinations have been
made. The prox- imity effect, the thinning out of the Lyman alpha
forest near a sight- line’s background quasar and explained at least
partly by the enhanced ionization from the quasar, is a key method to
measure J. A foreground proximity effect {FPE} should exist from
quasars close on the sky but at different z; it can constrain J and
test the enhanced ionization model. Galaxy clustering around the
quasar may modify the effect, but knowing the galaxy density around
the Lya forest should allow for corrections. We propose to measure the
FPE at z=1.2, which is advantageous because 1} the diffuse UV flux is
lower, and thus contrast with the UV flux of neighboring quasars is
higher, and 2} galaxies are easier to identify at z=1.2. We have good
knowledge of the physical volume we wish to study through surveys for
quasars, MgII absorbers and galaxies, to constrain the
redshift-dependent galaxy density along the line of sight. We will
analyze the results based on pixel opacities, which is more sensitive
to fluctuations in J than traditional line counting, and will compare
our results with cosmological simulations to derive estimates of the
UV background in the context of available physical models.

NIC2 9875

The Fundamental Plane of Massive Gas-Rich Mergers

We propose deep NICMOS H-band imaging of a carefully selected sample
of 33 luminous, late-stage galactic mergers. This program is part of a
comprehensive investigation of the most luminous mergers in the nearby
universe, the ultraluminous infrared galaxies {ULIGs}. The
high-resolution HST images will complement an extensive set of
ground-based data that include long-slit NIR spectra from a recently
approved Large VLT Programme. This unique dataset will allow us to
derive with unprecedented precision structural -and- kinematic
parameters for a large unbiased sample of objects spanning the entire
ULIG luminosity function. These data will refine the fundamental plane
of massive gas-rich mergers and enable us to answer the following
questions: {1} Do ultraluminous mergers form elliptical galaxies, and
in particular, giant ellipticals? {2} Do ULIGs evolve into optically
bright QSOs? The results from this detailed study of massive mergers
in the local universe will be relevant to understanding galaxy
formation and evolution at earlier epochs, and in particular, the
dusty sub-mm population that accounts for more than half of the star
formation at z > 1.

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

NIC2 9856

A near-IR imaging survey of submm galaxies with spectroscopic redshifts

Submillimeter {submm} surveys with SCUBA have identified a population
of obscured star-forming and active galaxies at high redshift. Our
recent spectroscopic campaigns with the Keck-10m telescope have
uncovered redshifts for 37 SCUBA galaxies. The wide redshift range of
the radio identified submm population {z=1-4} implies that many
varieties of sources driven by different physical processes may be
selected in a submm survey. Only HST observervations have the
resolution to detect any changes in the morphologies of SCUBA galaxies
with increasing cosmic time. We propose to use HST-NICMOS, ACS to
obtain 2-filter images of a sample of 15 SCUBA galaxies with redshifts
spanning z=0.8-3.5. Our goal is to understand what physical process
{major mergers?} drive their strong evolution and great luminosities,
and what the implications are for galaxy evolution models.

ACS/HRC 9823

Rings of Uranus: Dynamics, Particle Properties and Shepherding Moons

We propose to image the rings and small inner satellites of Uranus
using the High Resolution Channel of the ACS. The revolutionary
capabilities of the ACS will allow us to address a variety of
important questions relating to ring properties and ring-moon
interactions. Observations at a range of wavelengths and phase angles
will reveal the opposition surges of these rings and moons, providing
information on color and surface structure. Measurements of the ring
in front of the planet will provide complementary information on
optical depth; any variations of optical depth with wavelength will
reveal the rings’ poorly-constrained population of embedded dust. The
rings of Uranus are closing rapidly as the planet approaches equinox
in 2007, an event that takes place only every 42 years. Using this
opportunity, our observations will be repeated at different solar and
terrestrial tilt angles; this sequence of images will be particularly
valuable for constraining the physical thickness and packing density
of the rings. We will place particular emphasis on the rotational
variations of the Epsilon Ring, whose radial width {and therefore its
packing density} varies by a factor of five. In addition, a set of
deep exposures targeted just off the planet will enable us to detect
any 4-5 km moons embedded within the ring system. Dynamicists invoke
numerous such moons to “shepherd” the many sharp ring boundaries, so
this will serve as a definitive test of the theory.


Deep NICMOS Images of the UDF

The ACS Ultra Deep Field {UDF} images will greatly enhance the rich
suite of deep multi-wavelength images in the Chandra Deep Field South
{CDF–S}. We propose to complete the image set with deep near-IR
NICMOS images at 1.1 and 1.6 microns over a significant fraction of
the UDF, providing a critical link between the HST ACS and SIRTF
observations. The timely addition of the near-IR images ensures that
investigators will have images that span the spectrum from X-ray to
far IR. In recognition of the value of the near IR images this
proposal is submitted as a Treasury proposal with no proprietary
period. The proposal team will deliver science quality images,
mosaiced images covering 4.9 sq arc min, and a photometric catalog
complete to an AB mag of 28.2 in both the F110W and F160W filters. The
program also delivers a parallel extremely deep ACS field, 8′ away,
that reaches to within 0.6 mag of the UDF in the same filters as the
UDF. The scientific program of the proposal team focuses on the star
formation history of the universe, evolved galaxies at high redshift,
galaxies at the epoch of reionization, and the redshift evolution of
AGNs and ULIRGs. The HDF-N is currently the only field with
spatially-coincident deep HST imaging in both the optical and near-IR.
The small size of the HDF-N means that large scale structure is the
dominant error in the results from the HDF-N. Providing observations
in a field that is spatially uncorrelated is critically important. The
UDF/CDF-S fulfills that goal. The depth of the UDF ACS imaging, and
the wealth of Great Observatory and ground based observations in the
CDF-S, make these NICMOS observations uniquely valuable. An
extraordinarily rich array of science opportunities await the
community from the NICMOS UDF data.

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.


The local Hubble flow and the density field within 6 Mpc

Great progress has been made recently in accurate distance
measurements of nearby galaxies beyond the Local Group based on the
luminosity of the tip of the red giant branch {TRGB}. Over the last
three years, snapshot surveys with HST have provided us with the TRGB
distances for more than a hundred nearby galaxies obtained with an
accuracy of about 10%. The local velocity field within 5 Mpc exhibits
a significant anisotropy which disagrees with a spherical
Virgo-centric flow. The local Hubble flow is very cold, with 1-D rms
deviations of ~30 km/s. Cosmological simulations with Cold Dark Matter
can only realize such low dispersions with a combination of a low mean
density of matter and a substantial component with negative pressure.
There may be a constraint on the equation of state w=-p/rho. Our
observations will concentrate on 116 galaxies whose expected distances
lie within 4 – 6 Mpc, allowing us to trace a Dark Matter distribution
in the Local Volume with twice the information currently available.
The program is a good one for SNAP mode because the order and rate
that the observations are made are not very important, as long as
there is good completion over several years.

ACS/HRC 9747

An Imaging Survey of the Statistical Frequency of Binaries Among
Exceptionally-Young Dynamical Families in the Main Asteroid Belt

We propose an ambitious SNAPSHOT program to determine the frequency of
binaries among two very young asteroid families in the Main Belt, with
potentially profound implications. These families {of C- and S-type}
have recently been discovered {Nesvorny et al. 2002, Nature 417, 720},
through dynamical modeling, to have been formed at 5.8 MY and 8.3 MY
ago in catastrophic impact events. This is the first time such
precise and young ages have been assigned to a family. Main-belt
binaries are almost certainly produced by collisions, and we would
expect a young family to have a significantly higher frequency of
binaries than the background, because they may not yet have been
destroyed by impact or longer-term gravitational instabilities. In
fact, one of the prime observables from such an event should be the
propensity for satellites. This is the best way that new numerical
models for binary production by collisions {motivated largely by our
ground-based discoveries of satellites among larger asteroids}, can be
validated and calibrated. HST is the only facility that can be used to
search for binaries among such faint objects {V>17.5}. We will also
measure two control clusters, one being an “old” family, and the other
a collection of background asteroids that do not have a family
association, and further compare with our determined value for the
frequency of large main-belt binaries {2%}. We request visits to 180
targets, using ACS/HRC.

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.

NIC3 9735

ACS, NICMOS, and STIS Observations of Three Ongoing Mergers

We propose to make ACS {U, B, V, I, H_alpha}, NICMOS {J, H, K}, and
STIS {long-slit H_alpha} observations of NGC 520, NGC 2623, and NGC
3256, three merging galaxies in the middle of the Toomre Sequence and
currently in the throes of violent relaxation. Two of these {NGC 2623
and NGC 3256} are the most IR luminous galaxies in the sequence.
Hence, these ongoing mergers are ideal candidates for studying the
triggering mechanism responsible for the formation of stars and star
clusters. The ACS observations will allow us to age date the star
clusters, and reliably distinguish clusters from stars based on their
apparent sizes. They will also be used in conjunction with
ground-based measurements of the stellar velocity dispersion to
determine dynamical masses of the clusters and hence address the
question of whether the IMF is truncated. The NICMOS observations will
allow us to penetrate the dust and answer several fundamental
questions such as: What fraction of the young clusters are hidden by
dust? How do these clusters form and evolve? The STIS observations
will allow us to study the kinematics of the young cluster system and
measure the pressure and shock properties which may be triggering the
formation of the clusters. A better understanding of how mergers form
tremendous numbers of clusters and stars in the local universe will
help shed light on processes that were crucial during galaxy assembly
in the high-z universe.

WFPC2 9712

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

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

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.

FGS 9335

Masses of Pre-Main Sequence Binaries

We propose to continue to map the orbits of young star binaries in the
Taurus and Ophiuchus star forming regions. Our goal is to measure
their masses dynamically. This is important because there are still no
low mass young stars with reliably known masses so calculations of
their evolution to the main sequence are uncalibrated.


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 10082

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans

WFPC2 10075

WFPC2 CYCLE 12 Intflat and Viflat Sweeps and Filter Rotation Anomaly

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

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.


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.


Locating Ultraluminous X-Ray Sources

We propose to observe ultraluminous X-ray sources which are located
near objects bright both in the X-rays and the optical using Chandra
and HST. The presence of these reference objects will allow us to tie
the x-ray and optical references frames and achieve 0.1-0.2 arcsecond
relative position accuracy in searching for optical counterparts to
the ultraluminous x-ray sources. This will be a significant
improvement over the accuracy previously obtained for most ULXs
{limited by Chandra’s absolute astrometry} and will should permit
identification of individual counterparts.

STIS/CCD 10000

STIS Pure Parallel Imaging Program: Cycle 12

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


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

HSTAR 9209: GS Reacquisition (1,2,2) @ 315/13:02Z required two
attempts to achieve FL-DV on FGS 2.In GS Reacquisition that began @
315/13:56Z due to SSLE on FGS 2 during the first attempt. As it was a
GS Reacquisition and the second attempt was successful, there should
not have been any science impact due to this anomaly. This anomaly
was uncovered by OTA SE review of PTAS processing log from SA314N SMS
TC run. Under investigation.

HSTAR 9210: After successful GS Acquisition (1,2,1) @ 319/18:45Z and
GS Reacquisition @ 319/20:22Z, this GS pair required two attempts to
get to FL-DV in the GS Reacquisition that began @ 319/21:58Z due to
SSLE on FGS 2 during the first attempt. As it was a GS Reacquisition
and the seconds attempt was successful, there should not have been any
science impact due to this anomaly. This anomaly was uncovered by OTA
SE review of PTAS processing log from SA314N SMS TC run. Under

HSTAR 9214 GSACQ(2,1,1) fine lock backup, scan step limit exceeded on
FGS2. GSACQ(2,1,1) at 324/09:40:49 ended in fine lock backup on FGS 2
due to scan step limit exceeded on FGS 2 at 09:44:25. REACQ at
11:01:55 also ended in fine lock backup. Observations affected: ACS
196 to 212, NICMOS 57 to 58, STIS 71 to 73, WFPC 137 to 150. The guide
star acquisition for this observation was non-nominal, further
analysis will determine if a repeat observation is required.



                           SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq               14                        14
FGS REacq               17                        17
FHST Update             35                        35


Beta Testing with CCSPSS Release 3.3 scheduled 323/12:00Z – 17:00Z
with GDOC, SOC, and HITT using CCS “C” String (Test Mode) with CCS
Release 4.0.3 and PRD S07200.

HST Project Interface Test to verify DSN Desktops (1 Mbps) scheduled
323/13:00Z – 19:30Z with HST STOCC, JPL, GDOC, DSS 046, NISN, and SOC
using CCS “B” String (GSTND Test Mode) with CCS Release 4.0.3 and PRD
O06300T. The purpose of this testing is to verify the DSS 046
(Canberra) Desktop upgrades for 1 Mbps data.

SpaceRef staff editor.