Status Report

NASA Hubble Space Telescope Daily Report # 3539

By SpaceRef Editor
January 28, 2004
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




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.


The role of dark matter and intracluster gas in galaxy formation and
cluster evolution

We propose a fully-sampled mosaic of 41 ACS images to survey galaxy
morphologies and measure weak lensing signals to the turn-around
radius in the X-ray luminous cluster, MS0451-03 {z=0.54}. The aim is
to isolate the physical processes which affect the evolution of
cluster galaxy morphologies in the context of well-defined dynamical
system. The study will be used in contrast to a successful campaign
undertaken in Cycle 9 on a optically-selected target. By comparing
morphologies with spectroscopic and Chandra X-ray data, we will
quantify the role of the intracluster medium and associated
substructures and establish the timescales and physical regions within
which the various environmental processes occur.


An ACS/WFC H-alpha Survey of the Orion Nebula

We propose to survey nearly 500 square arcminutes of the Orion Nebula
in H-alpha using the ACS/WFC, increasing the sky coverage by an order
of magnitude over the sum of all previous HST observations. This
survey will, for the first time, sample the majority of young stars
and circumstellar environments in the extended Trapezium cluster of 2,
000 low-mass stars. Our primary goal is to determine the survival rate
and statistical properties of protoplanetary disks in the type of
radiation field and dynamical environment in which most stars are
born. The survey will be used to search for new silhouette disks,
bright proplyds, microjets, large-scale outflows, and to characterize
the properties of these objects as a function of location in the
nebula. We will determine accurate proper motions in regions where
previous HST data exist. However, 90% of our fields will be observed
with HST for the first time. This survey will provide the first
complete census of pre-main sequence objects and outflows in an HII
region and will constrain the extent of hazards to planet formation in
such environments. The images will also provide a legacy for future
stellar and nebular variability studies and proper motion measurements
by providing a first epoch data base.

ACS/WFPC2 9488

Cosmic Shear – with ACS Pure Parallel Observations

The ACS, with greater sensitivity and sky coverage, will extend our
ability to measure the weak gravitational lensing of galaxy images
caused by the large scale distribution of dark matter. We propose to
use the ACS in pure parallel {non- proprietary} mode, following the
guidelines of the ACS Default Pure Parallel Program. Using the HST
Medium Deep Survey WFPC2 database we have measured cosmic shear at
arc-min angular scales. The MDS image parameters, in particular the
galaxy orientations and axis ratios, are such that any residual
corrections due to errors in the PSF or jitter are much smaller than
the measured signal. This situation is in stark contrast with
ground-based observations. We have also developed a statistical
analysis procedure to derive unbiased estimates of cosmic shear from a
large number of fields, each of which has a very small number of
galaxies. We have therefore set the stage for measurements with the
ACS at fainter apparent magnitudes and smaller, 10 arc-second scales
corresponding to larger cosmological distances. We will adapt existing
MDS WFPC2 maximum likelihood galaxy image analysis algorithms to work
with the ACS. The analysis would also yield an online database similar
to that in

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 2

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.

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.


The rarest of sightlines: probing the metallicity of a DLA with a
nearby Low Surface Brightness galaxy

We seek to measure the gas-phase metallicity, dust content, and gas
kinematics in the interstellar medium {ISM} of the Low Surface
Brightness {LSB} galaxy SBS 1543+593, by observing absorption lines in
the spectrum of the background QSO HS 1543+5921. The QSO shines
directly through the center of the LSB galaxy, producing a damped
Lyman-alpha {DLA} line. This is the lowest redshift DLA system known
outside of the local group. Specifically, we wish to use the G140M
grating of STIS to: a} determine the metallicity of the interstellar
gas in the LSB galaxy by accurately measuring the column densities of
neutral hydrogen and sulphur; and b} estimate the amount of dust
present from a precise measure of the nickel column density. The
grating settings chosen to accomplish these goals will also allow us
to: c} characterize the kinematics of cool gas in the disk and halo of
the LSB galaxy by observing the line profiles of strong low ionization
species {Si II, O I, C I, C II, etc.}; and d} search for absorption
from NV which may arise in any highly ionized component of the ISM due
to accretion of intragroup gas onto the galaxy.

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 10084

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

17082-0 – Increase ROC Test TC Timer by 1 Orbit @ 027/1927z


                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq              8                         8
FGS REacq              3                         3
FHST Update            14                       14


Successfully completed Increase in ROC Test Trickle Charge Timer by 1
orbit (5760 seconds) @ 027/19:29Z(OR 17082 with attached Trickle
Charge procedure. Disabled Battery Rate-of-Charge Safing test, set-up
TMDIAGs to verify FSW changes, patched FSW to modify Trickle Charge
Timer to 22392 seconds, and enabled Battery Rate-of-Charge Safing
test. The change was made to allow additional time for EPS SEs to
bring SPAs back online and/or for the system to dig out of a SOC
deficit before autonomous safing action occurs. The test is still
configured to take autonomous safing action due to a gradual system
run-down (SWSP + loadshed will occur after approximately 4 orbits
without reaching Trickle Charge.

Changing the SPA Trim Relays and SSM486 FSW configuration to have the
+BB and -D SPAs offline is scheduled, first opportunity 028/14:09Z,
second opportunity 028/20:28Z (OR 17083 with attached script).

SpaceRef staff editor.