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Daily Report # 4346



 
 
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Old April 23rd 07, 02:25 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report # 4346

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 images. 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 z7 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)
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