Notice: For the foreseeable future, the daily reports may
contain
apparent discrepancies between some proposal descriptions
and the listed
instrument usage. This is due to the conversion of
previously approved
ACS WFC or HRC observations into WFPC2, or NICMOS
observations
subsequent to the loss of ACS CCD science capability in
late January.
HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4346
PERIOD COVERED: UT April 20,21,22, 2007 (DOY 110,111,112,)
OBSERVATIONS SCHEDULED
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.
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 any time.
WFPC2 11079
Treasury Imaging of Star Forming Regions in the Local
Group:
Complementing the GALEX and NOAO Surveys
We propose to use WFPC2 to image the most interesting
star-forming
regions in the Local Group galaxies, to resolve their
young stellar
populations. We will use a set of filters including F170W,
which is
critical to detect and characterize the most massive
stars, to whose hot
temperatures colors at longer wavelengths are not
sensitive. WFPC2's
field of view ideally matches the typical size of the
star-forming
regions, and its spatial resolution allows us to measure
indvidual
stars, given the proximity of these galaxies. The
resulting H- R
diagrams will enable studies of star-formation properties
in these
regions, which cover largely differing metallicities {a
factor of 17,
compared to the factor of 4 explored so far} and
characteristics. The
results will further our understanding of the
star-formation process, of
the interplay between massive stars and environment, the
properties of
dust, and will provide the key to interpret integrated
measurements of
star-formation indicators {UV, IR, Halpha} available for
several
hundreds more distant galaxies. Our recent deep surveys of
these
galaxies with GALEX {FUV, NUV} and ground-based imaging
{UBVRI, Halpha,
[OIII] and [SII]} provided the identification of the most
relevant SF
sites. In addition to our scientific analysis, we will
provide catalogs
of HST photometry in 6 bands, matched corollary
ground-based data, and
UV, Halpha and IR integrated measurements of the
associations, for
comparison of integrated star-formation indices to the
resolved
populations. We envisage an EPO component.
ACS/SBC 11050
ACS UV contamination monitor
The observations consist of imaging and spectroscopy with
SBC of the
cluster NGC 6681 in order to monitor the temporal
evolution of the UV
sensitivity of the SBC.
WFPC2 11002
A Census of LIRGs in Clusters of Galaxies in the First
Half of the
Universe from the IRAC Shallow Survey
The incidence of LIRGs and ULIRGs is roughly two orders of
magnitude
higher in the field at redshift z > 1, and at these
redshifts such
objects dominate the global star formation activity.
Mergers which fuel
such activity might be expected to enhance the frequency
of LIRGs in
dense environments. We propose to use MIPS to obtain a
census of LIRGs
in z > 1 galaxy clusters from a well defined sample
found in the IRAC
Shallow Survey. Supporting IRAC and HST ACS data are also
requested.
NIC3 10899
Identifying z>7 galaxies from J-dropouts
NICMOS Parallel Imaging campaigns covered enough sky {250
pointings}
with enough sensitivity in the 110W and 160W filters to
identify 6
extremely red resolved sources which are prime candidates
for J-band
dropouts. Their complete absence of detectable J band flux
can be caused
by an opaque Lyman cut-off at z=8-10. We propose to
followup these
candidates with NICMOS imaging and jointly propose Spitzer
IRAC
photometry. Deep F110W and Spitzer/IRAC 3.5/4.8 micron
imaging will
confirm if any of these candidates are indeed Lyman Break
galaxies
observed less than 500 Myrs after the Big Bang. Genuine
LBGs will remain
undetected in F110W, while being detected with flat
spectra in the IRAC
bands. The combined SED will provide information about the
stellar mass
of these galaxies, and the possible presence of evolved
stars or dust
reddening. The proposed observations will be sensitive
enough to detect
the F110W flux from galaxies as red as {J- H}=2.8 {AB
mags, 5 sigma}. If
any of the candidates are detected with bluer colors, they
will most
likely be exceptional "Distant Red Galaxies" at
z of 4 to 6. The
proposed data will constrain the stellar populations of
these
extraordinarily red galaxies, which would be candidates
for the
earliest, most massive galaxies which formed.
WFPC2 10890
Morphologies of the Most Extreme High-Redshift
Mid-IR-Luminous Galaxies
The formative phase of the most massive galaxies may be
extremely
luminous, characterized by intense star- and
AGN-formation. Till now,
few such galaxies have been unambiguously identified at
high redshift,
restricting us to the study of low-redshift ultraluminous
infrared
galaxies as possible analogs. We have recently discovered
a sample of
objects which may indeed represent this early phase in
galaxy formation,
and are undertaking an extensive multiwavelength study of
this
population. These objects are bright at mid-IR wavelengths
{F[24um]>0.8mJy}, but deep ground based imaging
suggests extremely faint
{and in some cases extended} optical counterparts
{R~24-27}. Deep K-band
images show barely resolved galaxies. Mid-infrared
spectroscopy with
Spitzer/IRS reveals that they have redshifts z ~ 2-2.5,
suggesting
bolometric luminosities ~10^{13-14}Lsun! We propose to
obtain deep ACS
F814W and NIC2 F160W images of these sources and their
environs in order
to determine kpc-scale morphologies and surface photometry
for these
galaxies. The proposed observations will help us determine
whether these
extreme objects are merging systems, massive obscured
starbursts {with
obscuration on kpc scales!} or very reddened {locally
obscured} AGN
hosted by intrinsically low-luminosity galaxies.
NIC1 10889
The Nature of the Halos and Thick Disks of Spiral Galaxies
We propose to resolve the extra-planar stellar populations
of the thick
disks and halos of seven nearby, massive, edge-on galaxies
using ACS,
NICMOS, and WFPC2 in parallel. These observations will
provide accurate
star counts and color-magnitude diagrams 1.5 magnitudes
below the tip of
the Red Giant Branch sampled along the two principal axes
and one
intermediate axis of each galaxy. We will measure the
metallicity
distribution functions and stellar density profiles from
star counts
down to very low average surface brightnesses, equivalent
to ~32 V-mag
per square arcsec. These observations will provide the
definitive HST
study of extra-planar stellar populations of spiral
galaxies. Our
targets cover a range in galaxy mass, luminosity, and
morphology and as
function of these galaxy properties we will provide: - The
first
systematic study of the radial and isophotal shapes of the
diffuse
stellar halos of spiral galaxies - The most detailed
comparative study
to date of thick disk morphologies and stellar populations
- A
comprehensive analysis of halo and thick disk metallicity
distributions
as a function of galaxy type and position within the
galaxy. - A
sensitive search for tidal streams - The first opportunity
to directly
relate globular cluster systems to their field stellar
population We
will use these fossil records of the galaxy assembly
process preserved
in the old stellar populations to test halo and thick disk
formation
models within the hierarchical galaxy formation scheme. We
will test
LambdaCDM predictions on sub-galactic scales, where it is
difficult to
test using CMB and galaxy redshift surveys, and where it
faces its most
serious difficulties.
WFPC2 10886
The Sloan Lens ACS Survey: Towards 100 New Strong Lenses
As a continuation of the highly successful Sloan Lens ACS
{SLACS} Survey
for new strong gravitational lenses, we propose one orbit
of ACS-WFC
F814W imaging for each of 50 high-probability strong
galaxy-galaxy lens
candidates. These observations will confirm new lens
systems and permit
immediate and accurate photometry, shape measurement, and
mass modeling
of the lens galaxies. The lenses delivered by the SLACS
Survey all show
extended source structure, furnishing more constraints on
the projected
lens potential than lensed-quasar image positions. In
addition, SLACS
lenses have lens galaxies that are much brighter than
their lensed
sources, facilitating detailed photometric and dynamical
observation of
the former. When confirmed lenses from this proposal are
combined with
lenses discovered by SLACS in Cycles 13 and 14, we expect
the final
SLACS lens sample to number 80--100: an approximate
doubling of the
number of known galaxy-scale strong gravitational lenses
and an
order-of-magnitude increase in the number of optical
Einstein rings. By
virtue of its homogeneous selection and sheer size, the
SLACS sample
will allow an unprecedented exploration of the mass
structure of the
early-type galaxy population as a function of all other
observable
quantities. This new sample will be a valuable resource to
the
astronomical community by enabling qualitatively new
strong lensing
science, and as such we will waive all but a short
{3-month} proprietary
period on the observations.
WFPC2 10884
The Dynamical Structure of Ellipticals in the Coma and
Abell 262
Clusters
We propose to obtain images of 13 relatively luminous
early type
galaxies in the Coma cluster and Abell 262 for which we
have already
collected ground based major and minor axis spectra and
images. The
higher resolution HST images will enable us to study the
central regions
of these galaxies which is crucial to our dynamical
modelling. The
complete data set will allow us to perform a full
dynamical analysis and
to derive the dark matter content and distribution, the
stellar orbital
structure, and the stellar population properties of these
objects,
probing the predictions of galaxy formation models. The
dynamical
analysis will be performed using an up-to-date
axi-symmetric orbit
superposition code.
WFPC2 10877
A Snapshot Survey of the Sites of Recent, Nearby
Supernovae
During the past few years, robotic {or nearly robotic}
searches for
supernovae {SNe}, most notably our Lick Observatory
Supernova Search
{LOSS}, have found hundreds of SNe, many of them in quite
nearby
galaxies {cz < 4000 km/s}. Most of the objects were
discovered before
maximum brightness, and have follow-up photometry and
spectroscopy; they
include some of the best-studied SNe to date. We propose
to conduct a
snapshot imaging survey of the sites of some of these
nearby objects, to
obtain late-time photometry that {through the shape of the
light and
color curves} will help reveal the origin of their
lingering energy. The
images will also provide high-resolution information on
the local
environments of SNe that are far superior to what we can
procure from
the ground. For example, we will obtain color-color and
color-magnitude
diagrams of stars in these SN sites, to determine the SN
progenitor
masses and constraints on the reddening. Recovery of the
SNe in the new
HST images will also allow us to actually pinpoint their
progenitor
stars in cases where pre- explosion images exist in the
HST archive.
This proposal is an extension of our successful Cycle 13
snapshot survey
with ACS. It is complementary to our Cycle 15 archival
proposal, which
is a continuation of our long-standing program to use
existing HST
images to glean information about SN environments.
WFPC2 10845
HUNTING FOR OPTICAL COMPANIONS TO BINARY MILLISECOND
PULSARS IN TERZAN 5
AND NGC6266
We propose deep WFPC2 and NICMOS observations to search
for optical
companions to binary millisecond pulsar {MSPs} in two
Globular Clusters
{GCs}: Terzan 5 and NGC6266. Terzan 5 has the largest MSP
population of
any GC: 33 MSP {17 in binary systems} have been discovered
up to now in
this stellar system. NGC6266 ranks fifth among the GC for
wealth of MSPs
but it is the only one in which all the {six} detected
MSPs are in
binary systems. Only 5 optical counterparts to binary MSP
companions are
known in GCs {two of them have been discovered by our
group}: hence even
the addition of a few new identifications are crucial to
investigate the
variety of processes occurring in binary MSPs in dense
environment. The
observations proposed here would easily double/triple the
existing
sample of known MSP companions, allowing the first
meaningful study of
the phenomena which drive the formation and evolution of
these exotic
systems. Moreover, since most of binary MSP in GC are
formed via stellar
interactions in the high density regions of the cluster,
the
determination of the nature of the companion and the
incidence of this
collisionally induced population have a significant impact
on our
knowledge of the cluster dynamics. Even more interesting,
the study of
the optical companions to NSs in a GC allows to derive
tighter
constraints {than those obtainable for NS binaries in the
galactic
field} on the properties {mass, orbital inclination and so
on} of the
compation star. This has, in turn, an intrisic importance
for
fundamental physics since it offers the opportunity of
measuring the
mass of the NS and hence to put constraints to the
equation of state of
matter at nuclear equilibrium density.
WFPC2 10829
Secular Evolution at the End of the Hubble Sequence
The bulgeless disk galaxies at the end of the Hubble
Sequence evolve at
a glacial pace relative to their more violent,
earlier-type cousins. The
causes of their internal, or secular evolution are
important because
secular evolution represents the future fate of all
galaxies in our
accelerating Universe and is a key ingredient to
understanding galaxy
evolution in lower-density environments at present. The
rate of secular
evolution is largely determined by the stability of the
cold ISM against
collapse, star formation, and the buildup of a central
bulge. Key
diagnostics of the ISM's stability are the presence of
compact molecular
clouds and narrow dust lanes. Surprisingly, edge-on, pure
disk galaxies
with circular velocities below 120 km/s do not appear to
contain such
dust lanes. We propose to obtain ACS/WFC F606W images of a
well-selected
sample of extremely late-type disk galaxies to measure the
characteristic scale size of the cold ISM and determine if
they possess
the unstable, cold ISM necessary to drive secular
evolution. Our sample
has been carefully constructed to include disk galaxies
above and below
the critical circular velocity of 120 km/s where the dust
properties of
edge-on disks change so remarkably. We will then use
surface brightness
profiles to search for nuclear star clusters and
pseudobulges, which are
early indicators that secular evolution is at work, as
well as measure
the pitch angle of the dust lanes as a function of radius
to estimate
the central mass concentrations.
WFPC2 10809
The nature of "dry" mergers in the nearby
Universe
Recent studies have shown that "dry" mergers of
red, bulge-dominated
galaxies at low redshift play an important role in shaping
today's most
massive ellipticals. These mergers have been identified in
extremely
deep ground-based images of red sequence galaxies at z ~
0.1. The
ground-based images reach surface brightness limits of AB
~ 29, but lack
the resolution to study the morphologies of the galaxies
inside the
effective radius. Here we propose to obtain ACS images of
a
representative sample of 40 of these red sequence
galaxies: 15 ongoing
dry mergers, 15 remnants, and 10 undisturbed objects. We
will measure
the isophote shapes and ellipticities of the galaxies,
their dust
content, morphological fine structure {shells and
ripples}, AGN content,
and their location on the Fundamental Plane. By comparing
galaxies in
different stages of the merging process we can constrain
the amount of
gas associated with these red mergers, the effect of
active nuclei, and
track structural changes. As two galaxies can be observed
in a single
orbit 20 orbits are requested to observe the 40 galaxies.
WFPC2 10798
Dark Halos and Substructure from Arcs & Einstein Rings
The surface brightness distribution of extended
gravitationally lensed
arcs and Einstein rings contains super-resolved
information about the
lensed object, and, more excitingly, about the smooth and
clumpy mass
distribution of the lens galaxies. The source and lens
information can
non-parametrically be separated, resulting in a direct
"gravitational
image" of the inner mass-distribution of
cosmologically-distant galaxies
{Koopmans 2005; Koopmans et al. 2006 [astro-ph/0601628]}.
With this goal
in mind, we propose deep HST ACS-F555W/F814W and
NICMOS-F160W WFC
imaging of 20 new gravitational-lens systems with
spatially resolved
lensed sources, of the 35 new lens systems discovered by
the Sloan Lens
ACS Survey {Bolton et al. 2005} so far, 15 of which are
being imaged in
Cycle-14. Each system has been selected from the SDSS and
confirmed in
two time- efficient HST-ACS snapshot programs {cycle
13&14}.
High-fidelity multi-color HST images are required {not
delivered by the
420s snapshots} to isolate these lensed images {properly
cleaned,
dithered and extinction-corrected} from the lens galaxy
surface
brightness distribution, and apply our "gravitational
maging" technique.
Our sample of 35 early-type lens galaxies to date is by
far the largest,
still growing, and most uniformly selected. This minimizes
selection
biases and small-number statistics, compared to smaller,
often
serendipitously discovered, samples. Moreover, using the WFC
provides
information on the field around the lens, higher S/N and a
better
understood PSF, compared with the HRC, and one retains
high spatial
resolution through drizzling. The sample of galaxy mass
distributions -
determined through this method from the arcs and Einstein
ring HST
images - will be studied to: {i} measure the smooth mass
distribution of
the lens galaxies {dark and luminous mass are separated
using the HST
images and the stellar M/L values derived from a joint
stellar-dynamical
analysis of each system}; {ii} quantify statistically and
individually
the incidence of mass-substructure {with or without
obvious luminous
counter- parts such as dwarf galaxies}. Since dark-matter
substructure
could be more prevalent at higher redshift, both results
provide a
direct test of this prediction of the CDM hierarchical
structure-formation model.
WFPC2 10786
Rotational state and composition of Pluto's outer
satellites
We propose an intricate set of observations aimed at
discovering the
rotational state of the newly discovered satellites of
Pluto, S/2005 P1
and S/2005 P2. These observations will indicate if the
satellites are in
synchronous rotation or not. If they are not, then the
observations will
determine the rotational period or provide tight
constraints on the
amplitude. The other primary goal is to extend the
wavelength coverage
of the colors of the surface and allow us to constrain the
surface
compositions of both objects. From these data we will also
be able to
significantly improve the orbits of P1 and P2, improve the
measurement
of the bulk density of Charon, and search for albedo
changes on the
surface of Pluto.
WFPC2 10524
Blue Stragglers: a key stellar population to probe
internal cluster
dynamics
This proposal is part of a coordinated project devoted to
understand the
interplay of globular cluster {GC} dynamics and the
formation and
evolution of blue straggler stars {BSS}. By using a
combination of HST
and ground-based observations we are constructing complete
BSS surveys
in a sample of GCs; complete BSS surveys require mid-UV
HST observations
in the center and wide field CCD ground based observations
under
excellent seeing conditions of the exterior. Up to now
only four
clusters have been surveyed in this way and the results
are surprising:
in three GCs {M3, 47 Tuc, NGC 6752} we have discovered
that the BSS
radial distribution is bimodal, highly peaked in the
cluster center,
rapidly decreasing at intermediate radii and rising again
at large radii
{Ferraro et al. 1997, 2004, Sabbi et al. 2004}, conversely
BSS
population in Omega Centauri does not show any signature
of the
segregation which would be expected for a class of objects
arising from
either stellar interactions or binarity {Ferraro et al.
2005}. These
observational facts are opening a new prospective in the
study of the
formation processes and evolution of BSS in GCs. By using
extensive
simulations, we demonstrated that the spatial distribution
of BSS
observed in 47 Tuc can be only reproduced if a sizable
fraction of BSS
is generated {via mass transfer in primordial binaries} in
the
peripheral region of the cluster {Mapelli et al 2004},
thus excluding a
purely collisional formation scenario. Here we propose
mid-UV imaging of
a few clusters suspected of harboring a large population
of central BSS
and a few known to have many BSS the external region.
These are good
candidates for determining accurate BSS radial
distributions. The modest
amount of time proposed here will go far to determine the
ubiquity of
BSS bimodality and to constrain models of dynamical
evolution. Since we
believe the proposed observations would be useful to the
entire stellar
community {for multifold purposes} we waive the propretary
period.
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
28
28
FGS
REacq
14
14
OBAD with Maneuver
84
84
SIGNIFICANT EVENTS: (None)