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07 April 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT       # 3336

PERIOD COVERED: DOY 97

Part 1 of 3

OBSERVATIONS SCHEDULED

NICMOS 8791

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.

WFPC2 9033

Measuring the mass distribution in the most distant, very X-ray
luminous galaxy cluster known

We propose to obtain a mosaic of deep HST/WFPC2 images to conduct a
weak lensing analysis of the mass distribution in the massive,
distant galaxy cluster ClJ1226.9+3332, recently discovered by us. At
z=0.888 this exceptional system is more X-ray luminous and more
distant than both MS1054.4-0321 and ClJ0152.7-1357, the previous
record holders, thus providing yet greater leverage for cosmological
studies of cluster evolution. ClJ1226.9+3332 differs markedly from
all other currently known distant clusters in that it exhibits little
substructure and may even host a cooling flow, suggesting that it
could be the first cluster to be discovered at high redshift that is
virialized. We propose joint HST and Chandra observations to
investigate the dynamical state of this extreme object. This project
will 1} take advantage of HST's superb resolution at optical
wavelengths to accurately map the mass distribution within 1.9 h^{-1}
50 Mpc via strong and weak gravitational lensing, and 2} use
Chandra's unprecedented resolution in the X-ray waveband to obtain
independent constraints on the gas and dark matter distribution in
the cluster core, including the suspected cooling flow region. As a
bonus, the proposed WFPC2 observations will allow us to test the
results by van Dokkum et al. {1998, 1999} on the properties of
cluster galaxies {specifically merger rate and morphologies} at z~0.8
from their HST study of MS1054.4-0321.

STIS/MA2 9096

Objective-Prism Spectroscopy of Massive Young Clusters.

The Space Telescope Imaging Spectrograph (MA2) was used to greatly
improve the spatial information by obtaining STIS NUV-MAMA
objective-prism spectroscopy in the 1300-3600 Angstrom range of three
nearby extragalactic regions with a total of ~ 10 MYCs since most of
the present knowledge of the UV spectral properties of massive young
clusters {MYCs} is based on IUE data with marginal spatial
resolution. Slitless techniques are seldom attempted on crowded
clusters due to the overlap among different sources. It is planned to
overcome that problem by observing with two different roll angles,
using comparison UV and optical images from the HST archive.

HST 9382

A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS
QSO MgII-FeII Systems.

We have searched the first public release of SDSS QSO spectra for
low-z {z<1.65} metal absorption lines and found over 200 large rest
equivalent width MgII-FeII systems. Previously, we empirically showed
that such systems are good tracers of large neutral gas columns,
with ~50% being classical damped Lyman alpha {DLA} systems
{N_HI>=2*10^20 cm^-2}. Here we propose to follow up a well-defined
subset of 79 of them to search for DLAs with 0.47 * Origin: SpaceBase(tm) Pt 1 -14.4- Van BC Canada 604-473-9358 (1:153/719.1)

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