Status Report

NASA Hubble Space Telescope Daily Report # 3386

By SpaceRef Editor
June 18, 2003
Filed under , ,

HUBBLE SPACE TELESCOPE

DAILY REPORT # 3386

PERIOD COVERED: DOY 168

OBSERVATIONS SCHEDULED

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.

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/WFC 9419

The Complete IMF of a Massive Young Cluster

We propose to use the large improvement in sensitivity and wide-field
resolution
provided by ACS to obtain for the first time the complete ~ 0.1 M_Sun to ~
100
M_Sun IMF of a single massive young cluster. We will obtain BVI + nebular
deep
{V ~ 27} WFC photometry of six cluster and one background pointings and we
will
use the auto-parallel capacity of ACS to simultaneously acquire deep NUV+U+V
photometry of selected regions in the cluster. Special care has been taken
to
treat all the complications which arise in the reduction of data for the
purpose
of calculating the IMF of a young cluster. We have chosen as our object of
study
N11 in the LMC because it arguably provides the best combination of stellar
mass
range {> 40 O stars, with several O3 stars}, spatial resolution {1 WFC pixel
=
0.0125 pc}, low extinction {E{B-V} ~ 0.1}, crowding, background confusion,
and
nebular contamination in comparison to other Galactic and Local Group
clusters.
It also has the advantage of having two separate regions, one which has
already
stopped forming stars and another one which is still forming them, thus
allowing
us to search for differences in the IMF between those two cases. The ACS
data
will be complemented with IR ground-based observations obtained using Gemini
South, for which we already have been awarded time.

ACS 9462

Systemic and Internal Proper Motions of the Magellanic Clouds from
Astrometry
with ACS

We request first epoch observations with ACS of Magellanic Cloud fields
centered
on background quasars. Second epoch observations will be requested ~ 5 years
later to allow the measurement of the systemic and internal proper motions
of
the Clouds with error <~0.05 mas/year. These motions are of fundamental
importance. The systemic motions of the LMC and SMC probe the gravitational
potential of the dark halo. The internal proper motion due to rotation can
be
exploited to yield a rotational parallax distance to the LMC; the first time
that this will be done for any galaxy. This is particularly important for
the
LMC because of its crucial role in the extragalctic distance ladder.
Previous
measurements of the proper motion of the LMC yield a systemic component
ranging
from 1.4 mas/year to 3.4 mas/year {differing by several times the quoted
errors}, with no useful determination of the internal motions. The main
problem
with measurements of the proper motion of the LMC has been the lack of a
sample
of background quasars to use as reference frame. We have recently been able
to
identify a sample of 54 quasars behind the Magellanic Clouds from their
variability characteristics in the MACHO database. With this sample and the
advent of ACS an accurate proper motion measurement has become possible for
the
very first time.

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/WFPC2 9481

Pure Parallel Near-UV Observations with WFPC2 within High-Latitude ACS
Survey
Fields

In anticipation of the allocation of ACS high-latitude imaging survey{s}, we
request a modification of the default pure parallel program for those WFPC2
parallels that fall within the ACS survey field. Rather than duplicate the
red
bands which will be done much better with ACS, we propose to observe in the
near-ultraviolet F300W filter. These data will enable study of the
rest-frame
ultraviolet morphology of galaxies at 0<z<1. We will determine the
morphological
k-correction, and the location of star formation within galaxies, using a
sample
that is likely to be nearly complete with multi-wavelength photometry and
spectroscopic redshifts. The results can be used to interpret observations
of
higher redshift galaxies by ACS.

ACS 9482

ACS Pure Parallel Lyman-Alpha Emission Survey {APPLES}

Ly-alpha line emission is an efficient tool for identifying young galaxies
at
high redshift, because it is strong in galaxies with young stars and little
or
no dust — properties expected in galaxies undergoing their first burst of
star- formation. Slitless spectroscopy with the ACS Wide-Field Camera and
G800L
grism allows an unmatched search efficiency for such objects over the
uninterrupted range 4 <~ z <~ 7. We propose the ACS Pure Parallel Ly-alpha
Emission Survey {“APPLES”}, to exploit this unique HST capability and so
obtain the largest and most uniform sample of high redshift Ly-alpha
emitters
yet. Parallel observations will allow this survey to be conducted with
minimal
impact on HST resources, and we will place reduced images and extracted
spectra
in the public domain within three months of observation. We aim to find ~
1000
Ly-alpha emitters, 5 times the biggest current sample of Ly-alpha emitters.
This
unprecedented sample will provide robust statistics on the populations and
evolution of Ly-alpha emitters between redshifts 4–7; a robust measurement
of
the reionization redshift completely independent of the Gunn-Peterson
trough;
spatial clustering information for Ly-alpha emitters which would let us
probe
their bias function and hence halo mass as a function of redshift; many
galaxies
at redshift exceeding 6; and lower redshift serendipitous discoveries.

WFPC2 9595

WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt3/3

This dark calibration program obtains 3 dark frames every day to provide
data
for monitoring and characterizing the evolution of hot pixels.

STIS 9606

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS 9608

CCD Bias Monitor – Part 2

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 9615

Cycle 11 MAMA Dark Monitor

This test performs the routine monitoring of the MAMA detector dark noise.
This
proposal will provide the primary means of checking on health of the MAMA
detectors systems through frequent monitoring of the background count rate.
The
purpose is to look for evidence of change in dark indicative of detector
problem
developing.

STIS 9633

STIS parallel archive proposal – Nearby Galaxies – Imaging and Spectroscopy

Using parallel opportunities with STIS which were not allocated by the TAC,
we
propose to obtain deep STIS imagery with both the Clear {50CCD} and
Long-Pass
{F28X50LP} filters in order to make color-magnitude diagrams and luminosity
functions for nearby galaxies. For local group galaxies, we also include
G750L
slitless spectroscopy to search for e.g., Carbon stars, late M giants and
S-type
stars. This survey will be useful to study the star formation histories,
chemical evolution, and distances to these galaxies. These data will be
placed
immediately into the Hubble Data Archive.

ACS 9649

ACS internal CTE monitor

The charge transfer efficiency {CTE} of the ACS CCD detectors will decline
as
damage due to on-orbit radiation exposure accumulates. This degradation will
be
closely monitored at regular intervals, because it is likely to determine
the
useful lifetime of the CCDs. All the data for this program is acquired using
internal targets {lamps} only, so all of the exposures should be taken
during
Earth occultation time {but not during SAA passages}. This program emulates
the
ACS pre-flight ground calibration and post-launch SMOV testing {program
8948},
so that results from each epoch can be directly compared. Extended Pixel
Edge
Response {EPER} and First Pixel Response {FPR} data will be obtained over a
range of signal levels for both the Wide Field Channel {WFC}, and the High
Resolution Channel {HRC}.

ACS 9674

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.

STIS 9708

STIS Pure Parallel Imaging Program: Cycle 11

This is the default archival pure parallel program for STIS during cycle 11.

ACS/HRC/WFC 9728

Tracing the History of Cosmic Expansion to z~2 with Type Ia Supernovae

Type Ia supernovae {SNe Ia} provide the only direct evidence for an
accelerating
universe, an extraordinary result that needs the most rigorous test. The
case
for cosmic acceleration rests on the observation that SNe Ia at z = 0.5 are
about 0.25 mag fainter than they would be in a universe without
acceleration. A
powerful and straightforward way to assess the reliability of the SN Ia
measurement and the conceptual framework of its interpretation is to look
for
cosmic deceleration at z > 1. This would be a clear signature of a mixed
dark-matter and dark-energy universe. Systematic errors in the SNe Ia result
attributed to grey dust or cosmic evolution of the SN Ia peak luminosity
would
not show this change of sign. We have obtained a toehold on this putative
“epoch of deceleration” with SN 1997ff at z = 1.7, and 3 more at z > 1
from
our Cycle 11 program, all found and followed by HST. However, this is too
important a test to rest on just a few objects, anyone of which could be
subject
to a lensed line-of-sight or misidentification. Here we propose to extend
our
measurement with observations of twelve SNe Ia in the range 1.0 < z < 1.5 or
6
such SNe Ia and 1 ultradistant SN Ia at z = 2, that will be discovered as a
byproduct from proposed Treasury and DD programs. These objects will provide
a
much firmer foundation for a conclusion that touches on important questions
of
fundamental physics.

FLIGHT OPERATIONS SUMMARY:

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

OPEN OPS REQs:
16618-2 – Contingency Activation of RTCS 21
16624-0 – Reset NCS Min/Max Buffer (Generic OR)

COMPLETED OPS REQs: None

                            SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq                6                          6
FGS REacq                11                        11
FHST Update              9                          9
LOSS of LOCK

SIGNIFICANT EVENTS:

Intercept SMS SA167N04_F1 was released @ 168/14:12Z, NSSC-1 load uplinked
during first
opportunity @ 168/19:13Z.

VEST-SIMSS to STOCC-CCS Interface Testing and Validation scheduled
169/10:00Z – 20:00Z
with GDOC, HITT, SE, SOC, and VEST using CCS "B" String and PRD
O06100TR1. The purpose
of this testing is to verify functionality of the SIMSS Interface between
the VEST
Structure and the STOCC CCS.

SpaceRef staff editor.