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 # 4344
PERIOD COVERED: UT April 18, 2007 (DOY 108)
OBSERVATIONS SCHEDULED
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 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 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.
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 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 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 11085
Europa in Eclipse: Tenuous Atmosphere, Electromagnetic
Activity and
Surface Luminescence HST Proposal 11085
We propose to image Europa during its orbital eclipse by
Jupiter. This
will form the basis of an investigation into the nature of
the tenuous
atmosphere, electromagnetic environment and surface
material of Europa.
We will compare the FUV oxygen line at 1356A to the
optical line at
6300A and seek optical auroral hydrogen emission in
Halpha. With broad
continuum filters, we will search for optical emissions
from other
atmospheric constituents and for fluorescence of the
surface material,
arising from the very high level of incident energetic
particle
radiation. The high spatial resolution of ACS will allow
us to fully
resolve scales of interest and allow us to distinguish
easily the
different terrains on Europa's surface. In particular we
wish to compare
luminesence in regions dominated by ice to those of
potentially organic
red material.
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:
17597-7 - FHST Stuck-on-Bottom Macro Execution
18037-3 - MSS/CSS KF Initialization Convergence Testing
18034-0 - FSW 3.1A EEPROM Installation
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq
08
08
FGS REacq
04
04
OBAD with Maneuver
24
24
SIGNIFICANT EVENTS:
FSW 3.1A was successfully installed in HST486 EEPROM
The post installation EEPROM dump completed at
108/13:55:05 and was
Successfully verified by FSW. The Bit Memory Integrity
Check was enabled
at 14:09:01.
The Kalman Filter was restarted at 108/13:26 during orbit
day and during
a T2G guiding interval. The filter was activated with the
default
configuration of MSS and CSS sensor inputs enabled. All
UKF parameters
showed nominal convergence and steady-state operation. The
test was an
MSS/CSS Initialization Test Case with the spacecraft
inertially fixed
during a fast changing B-field in orbit day (M_C_INF,case
#7).