Status Report

NASA Hubble Space Telescope Daily Report # 3494

By SpaceRef Editor
November 21, 2003
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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

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 9782

Measuring Black Hole Masses in Double Peaked Broad Lined AGNs

To date there have been few black hole {BH} mass estimates for
luminous broad line AGN, including those derived from reverberation
mapping. In this context, objects with “double-peaked” broad lines are
particularly important because the line emission is believed to arise
in a relativistically rotating accretion disk. If this model is
correct, then the BH mass can be determined directly from periodic
variations in the line-profile shape. In two cases {Arp 102B and NGC
1097} such variations have been claimed. The goal of this proposal is
to confront the relativistic disk model for the double-peaked Balmer
lines with independent limits on the central masses for 5 of the
nearest and brightest “double-peaked emitters” {NGC 1097, Arp 102B,
Pictor A, 3C390.3, 3C332}, determined by using STIS long-slit
spectroscopy to map the velocity field of circum-nuclear ionized gas.
These observations will critically test the idea that the line
emission in these objects comes from an accretion disk and thus
provide unique insights into the physical processes operating in both
the BLR and the “central engine”.


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.


Observations of Intermediate Mass Black Hole Candidate Ultra-Luminous
X-ray Sources

Ultra-luminous X-ray {ULX} sources are off-nuclear point sources in
nearby normal galaxies. Variability observed on the timescale of days,
weeks, and years signals that ULXS are accreting sources, likely
harboring black holes. However, the observed X-ray luminosity of these
systems far exceeds the Eddington limit for a 10 Msun black hole; some
ULXs may be intermediate mass black holes. The identification and
study of optical counterparts with HST will be central to better
understanding these objects. We propose to obtain deep U-B-V-I
exposures of 4 extremely bright ULXs in nearby spirals: NGC 1313 X-1
and X-2, M81 X-9 {Holmberg II X-1}, and M74 X-1. Each has a 0.5”
Chandra position, and X-ray luminosity and spectral characteristics
consistent with expectations for intermediate mass black holes. We
will use the colors we obtain, the magnitudes we measure, and any
source variability {also, correlated optical-X-ray variability from
simultaneous Chandra snapshots} to constrain the nature of the donor
stars and the black holes {10 Msun or 100-1000 Msun}, and the
formation and evolution scenarios for each system.

FGS 9348

The Distances to AM CVn stars

We propose to determine the parallaxes and proper motions of the five
brightest of the seven known AM CVn systems using the HST Fine
Guidance Sensors. AM CVn systems are binaries where mass is
transferred from a completely hydrogen-deficient, degenerate mass
donor to a white dwarf primary through a helium accretion disk. A
better understanding of these systems is crucial for a number of
reasons:, to study the late stages of binary evolution, to study the
effect of chemical composition on the physics of accretion discs; , o
to estimate their contribution to the Supernovae Ia rate and , to
estimate their contribution to the gravitational radiation background.
All these studies rely critically on a determination of the distances
to the currently known systems. With brightnesses in the range 13

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


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.


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/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 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 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.


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



                     SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq          7                         7
FGS REacq          8                         8
FHST Update        13                       13


SpaceRef staff editor.