HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4579
PERIOD COVERED: UT March 31, 2008 (DOY 091)
OBSERVATIONS SCHEDULED
WFPC2 11024
WFPC2 CYCLE 15 INTERNAL MONITOR
This calibration proposal is the Cycle 15 routine internal
monitor for
WFPC2, to be run weekly to monitor the health of the
cameras. A variety
of internal exposures are obtained in order to provide a
monitor of the
integrity of the CCD camera electronics in both bays {both
gain 7 and
gain 15 -- to test stability of gains and bias levels}, a
test for
quantum efficiency in the CCDs, and a monitor for possible
buildup of
contaminants on the CCD windows. These also provide raw
data for
generating annual super-bias reference files for the
calibration
pipeline.
FGS 11298
Calibrating Cosmological Chronometers: White Dwarf Masses
We propose to use HST/FGS1R to determine White Dwarf {WD}
masses. The
unmatched resolving power of HST/FGS1R will be utilized to
follow up
four selected WD binary pairs. This high precision
obtained with
HST/FGS1R simply cannot be equaled by any ground based
technique. This
proposed effort complements that done by CoI Nelan in
which a sample of
WDs is being observed with HST/FGS1R. This proposal will
dramatically
increase the number of WDs for which dynamical mass
measurements are
possible, enabling a better calibration of the WD
mass-radius relation,
cooling curves, initial to final mass relations, and
ultimately giving
important clues to the star formation history of our
Galaxy and the age
of its disk as well as in other galaxies. {This project is
part of
Subasavage's PhD thesis work at
NIC1/NIC2/NIC3 11330
NICMOS Cycle 16 Extended Dark
This takes a series of Darks in parallel to other
instruments.
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA calibration - CR Persistence Part 6
A new proceedure proposed to alleviate the CR-persistence
problem of
NICMOS. Dark frames will be obtained immediately upon
exiting the SAA
contour 23, and everytime 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 11070
WFPC2 CYCLE 15 Standard Darks - part II
This dark calibration program obtains dark frames every
week in order to
provide data for the ongoing calibration of the CCD dark
current rate,
and to monitor and characterize the evolution of hot
pixels. Over an
extended period these data will also provide a monitor of
radiation
damage to the CCDs.
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 11229
SEEDS: The Search for Evolution of Emission from Dust in
Supernovae with
HST and Spitzer
The role that massive stars play in the dust content of
the Universe is
extremely uncertain. It has long been hypothesized that
dust can
condense within the ejecta of supernovae {SNe}, however
there is a
frustrating discrepancy between the amounts of dust found
in the early
Universe, or predicted by nucleation theory, and inferred
from SN
observations. Our SEEDS collaboration has been carefully
revisiting the
observational case for dust formation by core- collapse
SNe, in order to
quantify their role as dust contributors in the early
Universe. As dust
condenses in expanding SN ejecta, it will increase in
optical depth,
producing three simultaneously observable phenomena: {1}
increasing
optical extinction; {2} infrared {IR} excesses; and {3}
asymmetric
blue-shifted emission lines. Our SEEDS collaboration
recently reported
all three phenomena occurring in SN2003gd, demonstrating
the success of
our observing strategy, and permitting us to derive a dust
mass of up to
0.02 solar masses created in the SN. To advance our
understanding of the
origin and evolution of the interstellar dust in galaxies,
we propose to
use HST's WFPC2 and NICMOS instruments plus Spitzer's
photometric
instruments to monitor ten recent core-collapse SNe for
dust formation
and, as a bonus, detect light echoes that can affect the
dust mass
estimates. These space-borne observations will be
supplemented by
ground-based spectroscopic monitoring of their optical
emission line
profiles. These observations would continue our 2-year HST
and Spitzer
monitoring of this phenomena in order to address two key
questions: Do
all SNe produce dust? and How much dust do they produce?
As all the SN
are within 15 Mpc, each SN stands an excellent chance of
detection with
HST and Spitzer and of resolving potential light echoes.
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:
11238 - GSAcq(1,3,1) failed to RGA Hold (Gyro Control)
GSAcq(1,3,1) scheduled at 091/09:09:04 - 09:17:09 failed to RGA Hold due
to
(QF1STOPF) stop flag indication on FGS-1. Pre-acquisition OBAD1 (RSS)
attitude correction value unavailable due to LOS. OBAD2 had (RSS) value
of
9.19arcseconds.
Post-acq OBAD/MAP scheduled at 091/10:06:54 had (RSS) value of 2546.26
arcseconds.
REACQ(1,3,1) at 10:40:07 was successful.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq
10
09
FGS REacq
05
05
OBAD with Maneuver
30 30
SIGNIFICANT EVENTS: (None)