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7 Apr 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT       # 3335

PERIOD COVERED: DOYs 94-96

Part 1 of 4

OBSERVATIONS SCHEDULED

ACS 9657

ACS Internal Flat Field Stability

The flat field stability and characterization obtained during the
ground calibration and SMOV phases will be tested and verified
through a sub-sample of the filter set. Only internal exposures with
the calibration lamps will be required.

ACS 9673

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 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. 

ACS 9401

The ACS Virgo Cluster Survey

We propose the most comprehensive imaging survey to date of
low-redshift, early-type galaxies. Our goal is to exploit the
exceptional imaging capabilities of the ACS by acquiring deep
images --- in the SDSS g^ and z^ bandpasses --- for 163 E, S0, dE,
dE, N and dS0 galaxies in Virgo, the nearest rich cluster. This
extraordinary dataset would likely constitute one of the principal
legacies of HST, and would have widespread applications for many
diverse areas of astrophysics. Our immediate scientific objectives
are threefold: {1} measure metallicities, ages and radii for the many
thousands of globular clusters {GCs} in these galaxies, and use this
information to derive the protogalactic mass spectrum of each
galaxy; {2} measure the central luminosity and color profile of each
galaxy, and use this information to carry out a completely
independent test of the merging hierarchy inferred from the GCs, with
the aid of N-body codes that simulate the merger of galaxies
containing massive black holes; and {3} calibrate the z^ -band SBF
method, measure Virgo's 3-D structure, and carry out the definitive
study of the GC luminosity function's precision as a standard candle.
Our proposed Virgo Cluster Survey will yield a database of
unprecedented depth, precision and uniformity, and will enable us to
study the record of galaxy and cluster formation in a level of detail
which will never be possible with more distant systems.

ACS 9583

The Great Observatories Origins Deep Survey: Imaging with ACS

We propose a Treasury program of ACS imaging as part of the Great
Observatories Origins Deep Survey {GOODS}, covering 320{square}', or
32* the area of the two original WFPC2 HDFs, to within 0.5--0.8 mag
of their depth in four ACS bands, BViz. The two GOODS fields, the
Hubble Deep Field North and Chandra Deep Field South, are the premier
deep survey areas from X-- ray to radio wavelengths. ACS data will
provide unique angular resolution, sensitivity, and wavelength
coverage to close the gap between the deepest Chandra and SIRTF
observations. Supported by extensive imaging and spectroscopy from
the VLT, Keck, Subaru, NOAO, Gemini, VLA, JCMT, and other facilities,
the combined GOODS data set will make it possible to map the
evolution of the Hubble sequence with redshift, reconstruct the
history of galaxy mass assembly, star formation and nuclear activity
from the epoch of reionization to the present, trace the growth of
density perturbations via cosmic shear, and, with properly phased
z--band observations, detect ~ 12 Type Ia supernovae at 1.2 * Origin: SpaceBase(tm) Pt 1 -14.4- Van BC Canada 604-473-9358 (1:153/719.1)

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