Status Report

NASA Hubble Space Telescope Daily Report #3515

By SpaceRef Editor
December 29, 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


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 10086

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.


Gravitational Microlensing in the NGC 3314A-B Galaxy Pair

Determining the composition of the dark matter that dominates the
masses of galaxies is an important unsolved problem, and the results
of the MACHO Collaboration suggest that some of Milky Way’s dark
matter may be in the form of very old white dwarfs. However, some have
argued that the excess of microlensing events seen by MACHO are due to
a larger than expected microlensing rate for lens stars in the LMC
itself or its tidal debris. We propose to address this question by
detecting microlensing events in the line-of-sight galaxy pair NGC
3314 A & B. The large line-of-sight distance between these galaxies
gives an optical depth that is 3-4 orders of magnitude larger than if
the source stars and lenses were in the same galaxy, and the fact that
the background galaxy is a spiral ensures that there will be a
sufficient number of bright, non-variable source stars. Our proposed
observations should have the sensitivity to detect microlensing by
both ordinary stars and dark matter in NGC 3314A {the foreground
galaxy}. If there are dark matter microlensing events to be found,
they can be clearly distinguished from stellar microlensing events
because they will occur outside the visible disk of NGC 3314A. If
baryonic dark matter is detected in NGC 3314A, we will be able to map
its radial density variation.


The COSMOS 2-Degree ACS Survey

We will undertake a 2 square degree imaging survey {Cosmic Evolution
Survey — COSMOS} with ACS in the I {F814W} band of the VIMOS
equatorial field. This wide field survey is essential to understand
the interplay between Large Scale Structure {LSS} evolution and the
formation of galaxies, dark matter and AGNs and is the one region of
parameter space completely unexplored at present by HST. The
equatorial field was selected for its accessibility to all
ground-based telescopes and low IR background and because it will
eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS
instrument. The imaging will detect over 2 million objects with I> 27
mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and
extremely red galaxies out to z ~ 5. COSMOS is the only HST project
specifically designed to probe the formation and evolution of
structures ranging from galaxies up to Coma-size clusters in the epoch
of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The
size of the largest structures necessitate the 2 degree field. Our
team is committed to the assembly of several public ancillary datasets
including the optical spectra, deep XMM and VLA imaging, ground-based
optical/IR imaging, UV imaging from GALEX and IR data from SIRTF.
Combining the full-spectrum multiwavelength imaging and spectroscopic
coverage with ACS sub-kpc resolution, COSMOS will be Hubble’s ultimate
legacy for understanding the evolution of both the visible and dark

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<z<1.9, which provides an excellent measure of current star
formation rate. We will also detect star-forming and active galaxies
in other redshift ranges using other emission lines. The grism
observations will produce by far the best available Halpha luminosity
functions over the crucial–but poorly observed–redshift range where
galaxies appear to have assembled most of their stellar mass. This key
process of galaxy evolution needs to be studied with IR data; we found
that observations at shorter wavelengths appear to have missed a large
fraction of the star-formation in galaxies, due to dust reddening. We
will also obtain deep F110W and F160W images, to examine the space
densities and morphologies of faint red galaxies. In addition to
carrying out the public parallels, we will make the fully reduced and
calibrated images and spectra available on-line, with some
ground-based data for the deepest parallel fields included.


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.

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.

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.

STIS/CCD 10085

STIS Pure Parallel Imaging Program: Cycle 12

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

STIS/CCD 10087

STIS HITM2 Lamp Brightness Check

We will measure the brightness of the HITM2 lamp at operating currents
3.8mA and 10mA in ACQ-type reference aperture exposures. We will check
whether the 10mA setting can be used in the ACQ procedure without
saturation. We will also take wavecals with HITM2 at 10mA at the
grating/central wavelength settings most commonly used for cycle 12

STIS/MA1 10034

Cycle 12 MAMA Dark Monitor

This test performs the routine monitoring of the MAMA detector dark
noise. This proposal will provide the primary means of checking on
health of the MAMA detectors systems through frequent monitoring of
the background count rate. The purpose is to look for evidence of
change in dark indicative of detector problem developing.

WFPC2 10068

WFPC2 CYCLE 12 Standard Darks

This dark calibration program obtains dark frames every week in order
to provide data for the ongoing calibration of the CCD dark current
rate, and to monitor and characterize the evolution of hot pixels.
Over an extended period these data will also provide a monitor of
radiation damage to the CCDs.

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 10072


This calibration proposal is the Cycle 12 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{gain 7 and gain 15}, a test for quantum efficiency in the CCDs, and a
monitor for possible buildup of contaminants on the CCD windows.

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 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<z<1. We will determine the morphological
k-correction, and the location of star formation within galaxies,
using a sample that is likely to be nearly complete with
multi-wavelength photometry and spectroscopic redshifts. The results
can be used to interpret observations of higher redshift galaxies by


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

FGS acquisitionss 8 for 8

FGS re-acquisitions 9 for 9

FHST updates 16 for 16



SpaceRef staff editor.