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Daily Report # 4344



 
 
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Old April 19th 07, 02:06 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report # 4344

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).
 




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