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 #4342
PERIOD COVERED: UT April 16, 2007 (DOY 106)
OBSERVATIONS SCHEDULED
NIC2 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 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 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 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 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.
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 10925
Imaging the Nearest Damped Lyman Alpha Absorbers
We propose to acquire broad-band and H-alpha imaging of
three bright,
very nearby host galaxies for damped Ly-alpha absorbers
{DLAs}. Our
targets are the only DLA hosts at z < 0.03 {i.e.,
spatial resolutions of
< 1.2 kpc}. The purpose of these observations is to
discover the
detailed morphology and kinematics and thus the origins of
the gas
giving rise to DLAs. While ground-based spectroscopy of
DLAs is used to
infer indirectly the evolution of galaxy metallicity and
thick disk
kinematics out to z > 4, only with HST imaging of the
very lowest
redshift DLA galaxies can we discover these relationships
directly. In
conjunction with H I 21-cm VLA emission maps, broad-band
and H-alpha
images of these DLAs will allow us to determine: {1} the
sites of active
star formation in the host galaxies and their relationship
to the QSO
sightline, {2} the presence of stellar streams, supernova
shells, or
bipolar "superwind" outflows in DLA host
galaxies, and {3} the detailed
spiral structure of the host galaxies, which will allow us
to use the
lower resolution H I 21-cm emission line images to
determine unambiguous
DLA kinematics with respect to the host galaxy {i.e., is
the DLA
rotating with the disk?}. Thus, the high resolution
imaging will allow
us to correctly interpret the kinematics and metallicity
information
provided by the H I 21-cm VLA maps and HST UV spectroscopy
to better
inform the high-z results.
WFPC2 11023
WFPC2 CYCLE 15 Standard Darks - part 1
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 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.
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
07
07
FGS
REacq 06
06
OBAD with Maneuver
24
24
SIGNIFICANT EVENTS: (None)