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21 April 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT     #3345

PERIOD COVERED:  DOY 108-110

Part 4 of 5

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.

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. 

STIS 9606

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS 9706

STIS Pure Parallel Imaging Program: Cycle 10

This is the default archival pure parallel program for STIS during
cycle 10.

STIS 9507

STIS/UV snapshot survey of bright AGN

We propose a UV spectroscopic snapshot survey of bright AGN,
quadrupling the number of Seyferts UV spectra and adding dozens of
new quasars, aimed at the following goals: beginenumerate em Finding
the relationship between the intrinsic luminosity of the AGN and the
maximum velocity {and width} of the outflow emanating from it, and
determining the frequency of outflows in low-z AGN as a function of
luminosity. em Surveying IGM absorption line systems in numerous new
sight-lines. em Identifying promising targets for observations with
the future highly sensitive Cosmic Origin Spectrograph.  endenumerate
A 35-minute snapshot with exposures in either the G140L or G230L will
yield spectra with a minimum S/N > 15 per resolution element at all
wavelengths for all our potential targets. This will allow us to be
sensitive to absorption lines to a limiting equivalent width of 0.3
Angstrom at the 3 Sigma level. In order to facilitate rapid
observational followup, we waive the data proprietary period
entirely.

STIS/CCD 9126

Galaxy Mass and the Fate of Luminous, Blue Compact Galaxies at z~0.6.

The Space Telescope Imaging Spectrograph (CCD) was used to obtain
long-slit spectra for a sample of 6 luminous, blue, compact galaxies
{LBCGs} at z ~ 0.6.  Despite being very luminous, LBCGs have velocity
widths Sigma ~ 60 kms and half-light radii r_e ~ 0.5''
{or R_e ~ 3Kpc}.  Small sizes and velocity widths suggest LBCGs are
low- mass stellar systems , while their blue colors, strong emission
lines and low M/L-ratios indicate they are undergoing a major
starburst. If the star-forming process halts after the current burst,
models predict that LBCGs will fade by ~2-4 magnitudes after a few
Gyrs to reach the low luminosities and surface brightnesses
characteristic of spheroidal galaxies.

STIS/CCD 9074

The Origin and Physics of Gamma-Ray Bursts.

The Space Telescope Imaging Spectrograph (CCD) was used to make
observations that will provide the most stringent tests yet performed
of the hypothesis that GRBs are powered by the collapse of massive
stars.  STIS CCD spectroscopy will be used to detect broad atomic
features of supernovae underlying GRB optical transients, at flux
levels more than a factor of three fainter than SN 1998bw.

STIS/CCD/MA1 9184

A Survey for Missing Baryons in Highly Ionized Intergalactic Gas at
Low Redshift.

The Space Telescope Imaging Spectrograph (CCD and MA1) was used
to observe six additional low-z QSOs with the STIS FUV E140M echelle
mode {7 km s^-1 resolution}.  Combined with archival data, this will
increase the sample redshift path by a factor of ~7 compared to the
published data.  With the echelle data, we will {1} measure the
number of O VI absorbers per unit redshift {dN/dz} and their minimum
cosmological mass density with a limiting equivalent width of
W_Lambda ~50 mAngstrom , {2} examine whether the O VI absorption
arises in photoionized, collisionally ionized, or multiphase gas,
and {3} study the dependence of the O VI system properties on
environment.  In addition to testing this prediction regarding the
location of the missing baryons, the data will have applications to
many other topics such as low-z LyAlpha absorbers and the physical
properties and abundances of gas in the Milky Way halo.

 - Continued -

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