HUBBLE SPACE TELESCOPE -
Continuing to collect World Class Science
DAILY REPORT # 4580
PERIOD COVERED: UT April 01,
2008 (DOY 092)
OBSERVATIONS SCHEDULED
FGS 11212
Filling the Period Gap for
Massive Binaries
The current census of binaries
among the massive O-type stars is
seriously incomplete for systems in the period range from
years to
millennia because the radial velocity variations are too
small and the
angular separations too close for easy detection. Here we
propose to
discover binaries in this observational gap through a Faint
Guidance
Sensor SNAP survey of
relatively bright targets listed in the Galactic O
Star
Catalog. Our primary goal is to
determine the binary frequency
among those in the cluster/association, field, and
runaway groups. The
results will help us assess the role of binaries in
massive star
formation and in the processes that lead to the ejection of
massive
stars from their natal clusters. The program will also
lead to the
identification of new, close binaries that will be targets of
long term
spectroscopic and high angular resolution observations to
determine
their masses and distances. The results will also be
important for the
interpretation of the spectra of suspected and newly identified
binary
and multiple systems.
NIC1/NIC2 11139
NICMOS Observations of the Microquasar GRS 1758-258
The galactic black hole
candidate GRS 1758-258 is normally one of the
brightest persistent gamma-ray sources in the vicinity of
the galactic
center. It is a microquasar
with relativistic radio jets emanating from
a central variable source. Microquasars
are excellent nearby test
laboratories for studying the complex accretion and outflow
processes
that take place near black hole horizons. Despite an
accurate location
provided by Chandra and the VLA and over a decade of
careful
ground-based studies, the optical/infrared counterpart to GRS
1758-258
remains unknown. A stellar counterpart is expected, but
the current
candidates are all more than 2 sigma from the center of the
error
circle. The ground-based infrared flux limits are also
right at the
values expected for the synchrotron emission from the
outflow from the
black hole, and possibly for the emission from the accretion
disk. This
leaves open the question as to what is powering this very
energetic
persistent source. Here we propose to use NICMOS to perform
broad-band
imaging of the GRS 1758- 258 error box. These images will
be more than
three magnitudes more sensitive than the current
ground-based ones. The
resulting spectra will reveal the thermal/non- thermal
nature of the
sources in the region of the error box, and the high
spatial resolution
images may reveal a jet structure. We propose to perform
three visits of
two orbits each spanning the suggested 18.45 day
binary orbital period
of the system: a correct counterpart identification
should be confirmed
by its variability. We will also aim to support the
HST observations
with X- and gamma-ray observations using Swift or
INTEGRAL, and with
longer wavelength observations from the ground.
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA calibration -
CR Persistence Part 6
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 i
mages. Each observation will need its own CRMAP, as
different SAA
passages leave different imprints on the NICMOS detectors.
NIC3 11120
A Paschen-Alpha
Study of Massive Stars and the ISM in the Galactic
Center
The Galactic center (GC) is a
unique site for a detailed study of a
multitude of complex astrophysical phenomena, which may be
common to
nuclear regions of many galaxies. Observable at
resolutions
unapproachable in other galaxies, the GC provides an unparalleled
opportunity to improve our understanding of the
interrelationships of
massive stars, young stellar clusters, warm and hot
ionized gases,
molecular clouds, large scale magnetic fields, and black
holes. We
propose the first large-scale hydrogen Paschen
alpha line survey of the
GC
using NICMOS on the Hubble Space Telescope. This survey will lead to
a high resolution and high sensitivity map of the Paschen alpha line
emission in addition to a map of foreground extinction,
made by
comparing Paschen alpha to radio
emission. This survey of the inner 75
pc of the Galaxy will provide an unprecedented and
complete search for
sites of massive star formation. In particular, we will
be able to (1)
uncover the distribution of young massive stars in this
region, (2)
locate the surfaces of adjacent molecular clouds, (3)
determine
important physical parameters of the ionized gas, (4)
identify compact
and ultra-compact HII regions throughout the GC. When
combined with
existing Chandra and Spitzer surveys as well as a wealth of
other
multi-wavelength observations, the results will allow us to address
such
questions as where and how massive stars form, how stellar
clusters are
disrupted, how massive stars shape and heat the surrounding
medium, and
how various phases of this medium are interspersed.
NIC3 11153
The Physical Nature and Age of
Lyman Alpha Galaxies
In the simplest scenario, strong
Lyman alpha emission from high redshift
galaxies would indicate that stellar populations younger
than 10 Myrs
dominate the UV. This does not, however, constrain the
stellar
populations older than 100 Myrs,
which do not contribute to UV light.
Also, the Lyman alpha line can
be boosted if the interstellar medium is
both clumpy and dusty. Different studies with small
samples have reached
different conclusions about the presence of dust and old
stellar
populations in Lyman alpha emitters. We propose HST- NICMOS
and
Spitzer-IRAC photometry of 35
Lyman-alpha galaxies at redshift
4.5<z<6.5, in order to
determine their spectral energy distribution
{SED}
extending through rest-frame optical. This will allow us to
measure accurately {1} The total stellar mass in these
objects,
including old stars which may have formed at redshifts {z > 8} not
easily probed by any other means. {2} The
dust extinction in the
rest-frame UV, and therefore a correction to their present
star-formation rates. Taken together, these two quantities will
yield
the star-formation histories of Lyman alpha galaxies,
which form fully
half of the known galaxies at z=4-6. They will tell us
whether these are
young or old galaxies by straddling the 4000A break.
Data from NICMOS is
essential for these compact and faint {i=25-26th
magnitude AB} high
redshift
galaxies, which are too faint for good near-IR photometry from
the ground.
WFPC2 11027
Visible Earth Flats
This proposal monitors flatfield stability. This proposal obtains
sequences of Earth streak flats to construct high quality
flat fields
for the WFPC2 filter set. These flat fields will allow
mapping of the
OTA illumination pattern and
will be used in conjunction with previous
internal and external flats to generate new pipeline superflats. These
Earth flats will complement the
Earth flat data obtained during cycles
4-14.
WFPC2 11029
WFPC2 CYCLE 15 Intflat Linearity Check and Filter Rotation Anomaly
Monitor
Intflat observations will be taken to provide a linearity
check: the
linearity test consists of a series of intflats
in F555W, in each gain
and each shutter. A combination of intflats,
visflats, and earthflats
will be used to check the repeatability of filter wheel
motions.
{Intflat
sequences tied to decons, visits 1-18 in prop 10363,
have been
moved to the cycle 15 decon
proposal xxxx for easier scheduling.} Note:
long-exposure WFPC2 intflats must be
scheduled during ACS anneals to
prevent stray light from the WFPC2 lamps from contaminating
long ACS
external exposures.
WFPC2 11083
The Structure, Formation and
Evolution of Galactic Cores and Nuclei
A surprising result has emerged
from the ACS Virgo Cluster Survey
{ACSVCS}, a program to obtain
ACS/WFC gz imaging for a large, unbiased
sample of 100 early-type galaxies in the Virgo Cluster.
On subarcsecond
scales {i.e., <0.1"-1"}, the HST brightness
profiles vary systematically
from the brightest giants {which have nearly constant
surface brightness
cores} to the faintest dwarfs {which have compact
stellar nuclei}.
Remarkably, the fraction of
galaxy mass contributed by the nuclei in the
faint galaxies is identical to that contributed by supermassive black
holes in the bright galaxies {0.2%}. These findings
strongly suggest
that a single mechanism is responsible for both types
of Central Massive
Object: most likely internally
or externally modulated gas inflows that
feed central black holes or lead to the formation of
"nuclear star
clusters". Understanding the history of gas accretion,
star formation
and chemical enrichment on subarcsecond
scales has thus emerged as the
single most pressing question in the study of nearby
galactic nuclei,
either active or quiescent. We propose an ambitious HST
program {199
orbits} that constitutes the next, obvious step forward:
high-resolution, ultraviolet {WFPC2/F255W} and infrared
{NIC1/F160W}
imaging for the complete ACSVCS sample. By capitalizing on
HST's unique
ability to provide high-resolution images with a sharp and
stable PSF at
UV and IR wavelengths, we will
leverage the existing optical HST data to
obtain the most complete picture currently possible for
the history of
star formation and chemical enrichment on these small
scales. Equally
important, this program will lead to a significant
improvement in the
measured structural parameters and density distributions
for the stellar
nuclei and the underlying galaxies, and provide a
sensitive measure of
"frosting"
by young stars in the galaxy cores. By virtue of its superb
image quality and stable PSF, NICMOS is the sole
instrument capable of
the IR observations proposed here. In the case of the
WFPC2
observations, high-resolution UV imaging {< 0.1"} is a
capability unique
to HST, yet one that could be lost at any time.
WFPC2 11128
Time Scales Of
Bulge Formation In Nearby Galaxies
Traditionally, bulges are
thought to fit well into galaxy formation
models of hierarchical merging. However, it is now
becoming well
established that many bulges formed through internal, secular
evolution
of the disk rather than through mergers. We call
these objects
pseudobulges. Much
is still unknown about pseudobulges, the most
pressing questions being: How, exactly, do they build up
their mass? How
long does it take? And, how many exist? We are after an
answer to these
questions. If pseudobulges form
and evolve over longer periods than the
time between mergers, then a significant population of pseudobulges is
hard to explain within current galaxy formation
theories. A pseudobulge
indicates that a galaxy has most likely not undergone a
major merger
since the formation of the disk. The ages of pseudobulges give us an
estimate for the time scale of this quiescent evolution. We
propose to
use 24 orbits of HST time to complete UBVIH imaging on
a sample of 33
nearby galaxies that we have observed with Spitzer in the
mid-IR. These
data will be used to measure spatially resolved stellar
population
parameters {mean stellar age, metallicity,
and star formation history};
comparing ages to star formation rates allows us to
accurately constrain
the time scale of pseudobulge
formation. Our sample of bulges includes
both pseudo- and classical bulges, and evenly samples
barred and
unbarred galaxies. Most of our sample is imaged, 13 have
complete UBVIH
coverage; we merely ask to complete missing observations so
that we may
construct a uniform sample for studying bulge formation. We
also wish to
compare the stellar population parameters to a variety of
bulge and
global galaxy properties including star formation rates,
dynamics,
internal bulge morphology, structure from bulge-disk
decompositions, and
gas content. Much of this data set is already or is
being assembled.
This will allow us to derive
methods of pseudobulge identification that
can be used to accurately count pseudobulges
in large surveys. Aside
from our own science goals, we will present this broad
set of data to
the community. Thus, we waive proprietary periods for
all observations.
WFPC2 11198
Pure Parallel Imaging in the
NDWFS Bootes Field
The NOAO Deep-Wide Field Survey
{NDWFS} Bootes field is the target of
one of the most extensive multiwavelength
campaigns in astronomy. In
addition to ground-based optical and near-infrared imaging,
deep radio
mapping, and extensive spectroscopy, this entire region
has been imaged
by the Chandra, Spitzer {IRAC and MIPS}, and GALEX
missions. Robust
photometric redshifts {calibrated
using over 20,000 spectroscopic
redshifts} exist
for all sources brighter than R=24.5 or than 13 uJy
at
4.5
microns. To enhance the value of
this data set, we propose pure
parallel observations for all approved Cycle 16 programs in
this region
that lack coordinated parallel observations. The
primary aim of this
program will be to provide a database useful for the broad
range of
science programs underway in this region.
WFPC2 11202
The Structure of Early-type
Galaxies: 0.1-100 Effective Radii
The structure, formation and
evolution of early-type galaxies is still
largely an open problem in cosmology: how does the
Universe evolve from
large linear scales dominated by dark matter to the
highly non-linear
scales of galaxies, where baryons and dark matter both
play important,
interacting, roles? To understand the complex physical
processes
involved in their formation scenario, and why they have the
tight
scaling relations that we observe today {e.g. the
Fundamental Plane}, it
is critically important not only to understand their
stellar structure,
but also their dark-matter distribution from the
smallest to the largest
scales. Over the last three years the SLACS collaboration
has developed
a toolbox to tackle these issues in a unique and
encompassing way by
combining new non-parametric strong lensing
techniques, stellar
dynamics, and most recently weak gravitational lensing, with
high-quality Hubble Space Telescope imaging and VLT/Keck
spectroscopic
data of early-type lens systems. This allows us to
break degeneracies
that are inherent to each of these techniques
separately and probe the
mass structure of early-type galaxies from 0.1 to 100
effective radii.
The large dynamic range to
which lensing is sensitive allows us both to
probe the clumpy substructure of these galaxies, as well
as their
low-density outer haloes. These methods have convincingly been
demonstrated, by our team, using smaller pilot-samples of SLACS
lens
systems with HST data. In this proposal, we request
observing time with
WFPC2 and NICMOS to observe 53
strong lens systems from SLACS, to obtain
complete multi-color imaging for each system. This would
bring the total
number of SLACS lens systems to 87 with completed HST
imaging and
effectively doubles the known number of galaxy-scale strong
lenses. The
deep HST images enable us to fully exploit our new
techniques, beat down
low-number statistics, and probe the structure and evolution
of
early-type galaxies, not only with a uniform data-set an
order of
magnitude larger than what is available now, but also with a
fully
coherent and self-consistent methodological approach!
WFPC2 11326
Polarizers Closeout (Internal Observations)
Verify stability of
polarization calibration.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft
Anomalies: (The following are preliminary reports
of potential non-nominal performance that will be investigated.)
HSTARS: (None)
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 11 11
FGS REacq 04 04
OBAD with Maneuver 30 30
SIGNIFICANT EVENTS: (None)
-
____________________________________________________________
Lynn F. Bassford
Hubble Space Telescope
CHAMP
CHAMP Flight Operations Team Manager
Lockheed Martin
NASA GSFC PH#: 301-286-2876
"The Hubble Space Telescope is
the astronomical observatory and key to unlocking the most cosmic mysteries of
the past, present and future." - 7/26/6