Status Report

NASA Hubble Space Telescope Daily Report # 3484

By SpaceRef Editor
November 7, 2003
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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.

ACS/HRC 9896

A Survey of Extinction Curves to Redshift z=1

The effects of dust are crucial to the study of galaxies {through
models of galaxy evolution and star formation rates/histories},
cosmology {e.g., through its effects on SNe Ia fluxes}, and the
interpretation of gamma-ray burst afterglows. ?However, classical
methods for obtaining precise extinction curves cannot be applied
outside the Local Group. Recently, we demonstrated that gravitational
lenses can be used to measure extinction curves at intermediate
redshifts with high accuracy. We propose a survey of the extinction
curves in 6 lens galaxies known to contain dust, to study the
evolution of dust properties in galaxies out to z=1. ?We will obtain
multi-wavelength photometry {6 filters from 8140 A to 2550 A} of each
system to {1} construct non-parametric extinction curves which overlap
the 2175 A feature, {2} measure R{V} to a 2-sigma accuracy better than
0.5 for parametric models of Galactic dust, and {3} discriminate
between Galactic and SMC extinction curves to better than 2-sigma
accuracy. The compact angular size of the lens systems {1-2 arcsec}
and the need for near-UV images means that HST is required to make the


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.

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.


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.

FGS 9888

Trigonometric Calibration of the Period- Luminosity Relations for
Fundamental and First-Overtone Galactic Cepheids

Cepheids are the primary distance indicators for the extragalactic
distance scale and the Hubble constant. The Hubble Constant Key
Project set the zero-point for their Cepheid distance scale by
adopting a distance to the LMC, averaged over a variety of techniques.
However, different methods give an LMC distance modulus ranging from
18.1 to 18.8, and the uncertainty in the Cepheid zero-point is now the
largest contributor to the error budget for H_0. Moreover, the low
metallicity of the LMC raises additional concerns, since the PL
relation probably depends on metallicity. The zero-point can be
determined from Hipparcos parallaxes of Galactic Cepheids out to
several hundred parsecs, but with a typical parallax error of 0.5-1
mas, the Hipparcos error bars are uncomfortably large for this
demanding application. By contrast, HST’s FGS1R interferometer can
achieve astrometric accuracy of 0.2 mas. We propose to use FGS1R to
determine trigonometric parallaxes for a sample of 9 nearby Cepheids,
including both fundamental {F} and first-overtone {FO} pulsators. We
show that the improvement in the PL relations for F and FO Cepheids
will be dramatic. We will determine the PL slopes from our nearby
solar- metallicity sample alone, without recourse to nearby galaxies
and the issue of [Fe/H] dependence. The zero-point will be determined
robustly to about 0.05 mag, based on accurate, purely geometrical
measurements. All of this can be achieved in the next few years with
HST, without having to wait for the technically demanding and risky
SIM and GAIA missions well into the next decade.

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

NIC1 9737

A NICMOS direct imaging search for giant planets around the seven
single white dwarfs in the Hyades

We propose to use the NIC1 camera on HST to search for massive giant
planets around the known seven single white dwarfs in the nearby
Hyades cluster at sub-arcsec separations. At an age of 625 Myr, the
white dwarfs had protogenitor masses of about 3 solar masses, and
massive gaseous giant planets should have formed in the massive
circumstellar disks around these ex Herbig A0 stars, probably at
orbital separations similar or slightly larger than that of Jupiter {5
AU} in our own solar system. Such planets would have survived the
post-Main Sequence mass loss of the parent star, and would have
migrated outward adiabatically by a factor 4.5, equal to the ratio of
initial to final stellar mass {3Mo/0.66Mo}, due to conservation of
orbital angular momentum during the mass loss {AGB and PN} phase. Thus
the orbital separation NOW would be 4.5 x 5 AU = 22.5 AU, which at the
distance of the Hyades {45 pc} corresponds to 0.50 arcsec. Simulations
with TinyTim then show that giant planets at this separation with
masses in the range 6-12 Jupiter masses and apparent J and H
magnitudes in the range 20.5-23.3 mag {from Baraffe or Burrows models}
can be spatially resolved around the Hyades white dwarfs. Their J and
H brightnesses are known to be 15 +/- 0.5 mag, implying a median
star-planet brightness ratio of 1000:1 {7.5 mag}. This combination of
dynamic range and orbital separation is observable with NICMOS, by
subtracting images taken at two roll angles. Therefore, the proposed
near-IR diffraction-limited observations in the F110W and F160W
filters promise to resolve giant planets around low-mass stars for the
first time. If successful, the observations would also prove that
giant planets do form around early-type stars more massive than the

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.

NIC2 9741

The Exciting Wavelength of Extended Red Emission

We propose to determine the wavelength of the photons which excite
Extended Red Emission {ERE} by mapping the small scale structure of
ERE and molecular hydrogen {H_2} in the reflection nebulae NGC 2023
and 7023. Both of these nebulae display sharp narrow ERE-filaments
within photodissociation regions {PDR} which also show infrared H_2
fluorescence. In these opically thick filaments, different wavelength
photons penetrate to different depths. By comparing the widths of
these filaments in ERE and H_2 we will determine the exciting
wavelength of ERE. This is possible because the combined opacity of
dust and H_2 to the exciting radiation {lambda < 1100 A} of H_2 fluorescence is known, and the comparison of the thickness of the ERE and H_2 filaments will allow a determination of the dust opacity at the wavelength at which ERE is being excited. This is a sensitive test to distinguish between different materials which have been proposed as the carrier of ERE {e.g., carbon or silicon nanoparticles, polycyclic aromatic hydrocarbon molecules, hydrogenated amorphous carbon, etc.}, because the photoluminescense excitation spectra of these different materials differ by large amounts. Identifying the material which produces ERE is important as recent work on ERE in the diffuse interstellar medium has shown that the material which produces ERE comprises a significant component of dust grains.


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/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 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 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.

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


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

HSTAR 9190: GS Acquisition (1,2,2) @ 309/11:55:08Z, which began
during ZOE, resulted in FL backup, after multiple attempts, due to
SSLE on FGS 2. FHST Map @ 309/12:03:24Z showed (RSS) 3-axis vehicle
error of ~ 16.00 arcsec. Under investigation.



                            SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq                11                       11
FGS REacq                7                          7
FHST Update              19                        19


SpaceRef staff editor.