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Subject: Daily 3359

09 May 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT # 3359

PERIOD COVERED: DOY 128

Part 2 of 3

ACS 9468

ACS Grism Parallel Survey of Emission- line Galaxies at Redshift
z pl 7

We propose an ACS grism parallel survey to search for emission-line
galaxies toward 50 random lines of sight over the redshift interval
0 < zpl 7. We request ACS parallel observations of duration more
than one orbit at high galactic latitude to identify ~ 300 HAlpha
emission-line galaxies at 0.2pl zpl 0.5, ~ 720 O IILambda3727
emission-line galaxies at 0.3pl zpl 1.68, and pg  1000 Ly-alpha
emission-line galaxies at 3pl zpl 7 with total emission line flux
fpg 2* 10^-17 ergs s^-1 cm^-2 over 578 arcmin^2. We will obtain
direct images with the F814W and F606W filters and dispersed images
with the WFC/G800L grism at each position. The direct images will
serve to provide a zeroth order model both for wavelength calibration
of the extracted 1D spectra and for determining extraction apertures
of the corresponding dispersed images. The primary scientific
objectives are as follows: {1} We will establish a uniform sample of
HAlpha and O II emission-line galaxies at z<1.7 in order to obtain
accurate measurements of co-moving star formation rate density versus
redshift over this redshift range. {2} We will study the spatial and
statistical distribution of star formation rate intensity in
individual galaxies using the spatially resolved emission-line
morphology in the grism images. And {3} we will study high-redshift
universe using Ly-alpha emitting galaxies identified at z pl 7 in
the survey. The data will be available to the community immediately
as they are obtained.

ACS 9480

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. 

NICMOS 9484

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 9506

A SNAPSHOT SURVEY OF HIGH COLUMN DENSITY, LOW-Z LyAlpha ABSORBERS

We propose a STIS G140L spectroscopic Snapshot program of bright
{V<=16.5} AGN not previously observed in the UV to discover new
high-column density {N_H >= 10^15 cm^-2} LyAlpha absorbers in the
local Universe {z <= 0.45}. Many more of these high column density
systems are needed because: {1} They contribute most of the baryons
to the local IGM; {2} They include systems for which valuable
metallicity and D/H measurements can be made with the Cosmic Origins
Spectrograph {COS}; {3} They include many of the ``warm-hot''
absorbers, thought to be a large baryon reservoir in the local
Universe; and {4} They are most likely to be ``associated'' with
galaxy halos. Because of their low-z, many of these absorbers can be
located relative to galaxies of known redshifts, allowing an
immediate scientific return from these snapshots. Perhaps the most
important, lasting results of this survey require higher resolution
reobservations with COS by our GTO team. Using these snapshots to
select the best targets, we will obtain COS R~22, 000 spectra to
determine the D/H and metallicity of absorbers in galaxy halos,
groups, and voids. We will use pairs and ``constellations'' of AGN to
determine absorber sizes, shapes, and covering factors. Candidate
``warm-hot'' absorbers will be reobserved with COS to determine their
numbers accurately and to assess their metallicity, sizes, and
relationships to galaxies and galaxy groups.

WFPC2 9594

WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt2/3

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

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 1x1, 1x2, 2x1, and 2x2 bin settings at
gain=1, and 1x1 at gain = 4, to build up high-S/N superbiases and
track the evolution of hot columns.

 - Continued -

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