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Daily Report #5018



 
 
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Old January 25th 10, 03:46 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #5018

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5018

PERIOD COVERED: 5am January 22 - 5am January 25, 2010 (DOY 022/10:00z-025/10:00z)

OBSERVATIONS SCHEDULED

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more
reliably removed from science data using darks taken with the same
exposure sequences as the science data, than with a single dark
current image scaled by desired exposure time. Therefore, dark current
images must be collected using all sample sequences that will be used
in science observations. These observations will be used to monitor
changes in the dark current of the WFC3-IR channel on a day- to-day
basis, and to build calibration dark current ramps for each of the
sample sequences to be used by Gos in Cycle 17. For each sample
sequence/array size combination, a median ramp will be created and
delivered to the calibration database system (CDBS).

WFC3/IR 11916

IR Intrapixel Sensitivity

In order to characterize the periodic intrapixel sensitivity variation
(IPSV) of the WFC3 IR array, we will analyze full-frame IR
observations of a star field (in the Omega Centauri globular cluster)
in three bandpasses (F110W, F160W, and F098M) dithered on an NxN grid.
The measurements will be used to quantify systematic trends in
aperture photometry of stars with pixel phase, defined as (x mod 1, y
mod 1), where (x, y) is the center of the stellar image at subpixel
precision. Grid sizes of N=2 and N=3 are justifed in Additional
Comments of Proposal Description.

WFC3/IR 11915

IR Internal Flat Fields

This program is the same as 11433 (SMOV) and depends on the completion
of the IR initial alignment (Program 11425). This version contains
three instances of 37 internal orbits: to be scheduled early, middle,
and near the end of Cycle 17, in order to use the entire 110-orbit
allocation.

In this test, we will study the stability and structure of the IR
channel flat field images through all filter elements in the WFC3-IR
channel. Flats will be monitored, i.e. to capture any temporal trends
in the flat fields and delta flats produced. High signal observations
will provide a map of the pixel-to- pixel flat field structure, as
well as identify the positions of any dust particles.

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the
UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.
Initially found via an unexpected bowtie-shaped feature in flatfield
ratios, subsequent lab tests on similar e2v devices have since shown
that it is also present as simply an overall offset across the entire
CCD, i.e., a QE offset without any discernable pattern. These lab
tests have further revealed that overexposing the detector to count
levels several times full well fills the traps and effectively
neutralizes the bowtie. Each visit in this proposal acquires a set of
three 3x3 binned internal flatfields: the first unsaturated image will
be used to detect any bowtie, the second, highly exposed image will
neutralize the bowtie if it is present, and the final image will allow
for verification that the bowtie is gone.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set
of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K
subarray biases are acquired at less frequent intervals throughout the
cycle to support subarray science observations. The internals from
this proposal, along with those from the anneal procedure (Proposal
11909), will be used to generate the necessary superbias and superdark
reference files for the calibration pipeline (CDBS).

ACS/WFC3 11882

CCD Hot Pixel Annealing

All the data for this program is acquired using internal targets
(lamps) only, so all of the exposures should be taken during Earth
occultation time (but not during SAA passages). This program emulates
the ACS pre-flight ground calibration and post launch SMOV testing
(program 8948), so that results from each epoch can be directly
compared. Extended Pixel Edge Response (EPER) and First Pixel Response
(FPR) data will be obtained over a range of signal levels for the Wide
Field Channel (WFC). The High Resolution Channel (HRC) visits have
been removed since it could not be repaired during SM4.

ACS/WFC3 11879

CCD Daily Monitor (Part 1)

This program comprises basic tests for measuring the read noise and
dark current of the ACS WFC and for tracking the growth of hot pixels.
The recorded frames are used to create bias and dark reference images
for science data reduction and calibration. This program will be
executed four days per week (Mon, Wed, Fri, Sun) for the duration of
Cycle 17. To facilitate scheduling, this program is split into three
proposals. This proposal covers 352 orbits (22 weeks) from 31 August
2009 to 31 January 2010.

STIS/MA1/MA2 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the
MAMA detectors.

The basic monitor takes two 1380s ACCUM darks each week with each
detector. However, starting Oct 5, pairs are only included for weeks
that the LRP has external MAMA observations planned. The weekly pairs
of exposures for each detector are linked so that they are taken at
opposite ends of the same SAA free interval. This pairing of exposures
will make it easier to separate long and short term temporal
variability from temperature dependent changes.

For both detectors, additional blocks of exposures are taken once
every six months. These are groups of five 1314s FUV-MAMA Time-Tag
darks or five 3x315s NUV ACCUM darks distributed over a single
SAA-free interval. This will give more information on the brightness
of the FUV MAMA dark current as a function of the amount of time that
the HV has been on, and for the NUV MAMA will give a better measure of
the short term temperature dependence.

STIS/CCD 11846

CCD Bias Monitor-Part 1

The purpose of this proposal is to monitor the bias in the 1x1, 1x2,
2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up
high-S/N superbiases and track the evolution of hot columns.

STIS/CCD 11844

CCD Dark Monitor Part 1

The purpose of this proposal is to monitor the darks for the STIS CCD.

STIS/CCD/MA1/MA2 11839

The Cycles of Alpha Centauri

This is the HST part of a joint Chandra/HST observing program. The
objective of the HST part is to obtain new UV spectra of both
components of the Alpha Centauri binary: the primary ("Alpha Cen A")
is a near twin of the Sun, while the companion ("B") is an early K
dwarf, slightly less massive, smaller and less luminous than the Sun.
The orbital period is 80 yr, and the two stars currently are separated
by about 8". The Alpha Cen system has been the subject of long term
coronal X-ray monitoring by four successive generations of space
observatories, and extensive UV measurements were obtained
periodically during the IUE era, from the late 1970's to late 1990's.
The present program will obtain new STIS echelle spectra of both
stars, which each were observed in selected wavelength windows by GHRS
in the mid-1990's, and Alpha Cen A later by STIS in an extensive
high-res program in 1999, although B unfortunately never was recorded
by STIS.

STIS/CCD/MA1 11737

The Distance Dependence of the Interstellar N/O Abundance Ratio: A
Gould Belt Influence?

The degree of elemental abundance homogeneity in the interstellar
medium is a function of the enrichment and mixing processes that
govern galactic chemical evolution. Observations of young stars and
the interstellar gas within ~500 pc of the Sun have revealed a local
ISM that is so well- mixed it is having an impact on ideas regarding
the formation of extrasolar planets. However, the situation just
beyond the local ISM is not so clear. Sensitive UV absorption line
measurements have recently revealed a pattern of inhomogeneities in
the interstellar O, N, and Kr gas-phase abundances at distances of
~500 pc and beyond that appear nucleosynthetic in origin rather than
due to dust depletion. In particular, based on a sample of 13
sightlines, Knauth et al. (2006) have found that the nearby stars (d
500 pc) exhibit a mean interstellar N/O abundance ratio that is
significantly higher (0.18 dex) than that toward the more distant
stars. Interestingly, all of their sightlines lie in the sky vicinity
of the Gould Belt of OB associations, molecular clouds, and diffuse
gas encircling the Sun at a distance of ~400 pc. Is it possible that
mixing processes have not yet smoothed out the recent ISM enrichment
by massive stars in the young Belt region? By measuring the
interstellar N/O ratios in a strategic new sample of sightlines with
STIS, we propose to test the apparent N/O homogeneity inside the Gould
Belt and determine if the apparent decline in the N/O ratio with
distance is robust and associated with the Belt region.

WFC3/ACS/UVIS 11724

Direct Age Determination of the Local Group dE Galaxies NGC 147 and
NGC 185

The origin of dwarf elliptical (dE) galaxies remains a mystery and the
dE galaxies of the Local Group provide the best opportunity to study
this galaxy class in detail. We propose to obtain ACS photometry of
main sequence turnoff stars in the M31 dE satellites NGC 147 and NGC
185. Because these galaxies have little to no stars younger than 1
Gyr, resolving the main sequence turnoff is required to directly
quantify their star formation histories. NGC 147 and NGC 185 are the
only two dEs for which a clean measurement is feasible with the HST.
This proposal was accepted in Cycle 15, but little data were taken
before the failure of ACS. The main sequence turnoffs of NGC 147 and
NGC 185 are expected to be at an apparent magnitude of V=29; we
request F606W/F814W imaging one half magnitude fainter than this limit
(three magnitudes fainter than the deepest previous dE observations).
Quantifying the ratio of old to intermediate-age stars will allow us
to discriminate between competing models of dE formation. On-going
Keck/DEIMOS spectroscopy of several hundred red giant stars in each of
these two dE galaxies, coupled with dynamical modeling and spectral
synthesis, will complement the ACS measurement by providing
information on chemical abundance patterns, dark matter content and
internal dynamics. The proposed ACS data will be the first to directly
quantify the onset and duration of star formation episodes in dE
galaxies, and will thereby form the cornerstone in what promises to be
the most comprehensive study of this class of galaxies.

WFC3/ACS/IR 11677

Is 47 Tuc Young? Measuring its White Dwarf Cooling Age and Completing
a Hubble Legacy

With this proposal we will firmly establish the age of 47 Tuc from its
cooling white dwarfs. 47 Tuc is the nearest and least reddened of the
metal-rich disk globular clusters. It is also the template used for
studying the giant branches of nearby resolved galaxies. In addition,
the age sensitive magnitude spread between the main sequence turnoff
and horizontal branch is identical for 47 Tuc, two bulge globular
clusters and the bulge field population. A precise relative age
constraint for 47 Tuc, compared to the halo clusters M4 and NGC 6397,
both of which we recently dated via white dwarf cooling, would
therefore constrain when the bulge formed relative to the old halo
globular clusters. Of particular interest is that with the higher
quality ACS data on NGC 6397, we are now capable with the technique of
white dwarf cooling of determining ages to an accuracy of +/-0.4 Gyrs
at the 95% confidence level. Ages derived from the cluster turnoff are
not currently capable of reaching this precision. The important role
that 47 Tuc plays in galaxy formation studies, and as the metal-rich
template for the globular clusters, makes the case for a white dwarf
cooling age for this metal-rich cluster compelling.

Several recent analyses have suggested that 47 Tuc is more than 2 Gyrs
younger than the Galactic halo. Others have suggested an age similar
to that of the most metal poor globular clusters. The current
situation is clearly uncertain and obviously a new approach to age
dating this important cluster is required.

With the observations of 47 Tuc, this project will complete a legacy
for HST. It will be the third globular cluster observed for white
dwarf cooling; the three covering almost the full metallicity range of
the cluster system. Unless JWST has its proposed bluer filters (700
and 900 nm) this science will not be possible perhaps for decades
until a large optical telescope is again in space. Ages for globular
clusters from the main sequence turnoff are less precise than those
from white dwarf cooling making the science with the current proposal
truly urgent.

WFC3/UVIS 11657

The Population of Compact Planetary Nebulae in the Galactic Disk

We propose to secure narrow- and broad-band images of compact
planetary nebulae (PNe) in the Galactic Disk to study the missing link
of the early phases of post-AGB evolution. Ejected AGB envelopes
become PNe when the gas is ionized. PNe expand, and, when large
enough, can be studied in detail from the ground. In the interim, only
the HST capabilities can resolve their size, morphology, and central
stars. Our proposed observations will be the basis for a systematic
study of the onset of morphology. Dust properties of the proposed
targets will be available through approved Spitzer/IRS spectra, and so
will the abundances of the alpha-elements. We will be able thus to
explore the interconnection of morphology, dust grains, stellar
evolution, and populations. The target selection is suitable to
explore the nebular and stellar properties across the galactic disk,
and to set constraints on the galactic evolutionary models through the
analysis of metallicity and population gradients.

WFC3/UVIS/IR 11644

A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into
the Formation of the Outer Solar System

The eight planets overwhelmingly dominate the solar system by mass,
but their small numbers, coupled with their stochastic pasts, make it
impossible to construct a unique formation history from the dynamical
or compositional characteristics of them alone. In contrast, the huge
numbers of small bodies scattered throughout and even beyond the
planets, while insignificant by mass, provide an almost unlimited
number of probes of the statistical conditions, history, and
interactions in the solar system. To date, attempts to understand the
formation and evolution of the Kuiper Belt have largely been dynamical
simulations where a hypothesized starting condition is evolved under
the gravitational influence of the early giant planets and an attempt
is made to reproduce the current observed populations. With little
compositional information known for the real Kuiper Belt, the test
particles in the simulation are free to have any formation location
and history as long as they end at the correct point. Allowing
compositional information to guide and constrain the formation,
thermal, and collisional histories of these objects would add an
entire new dimension to our understanding of the evolution of the
outer solar system. While ground based compositional studies have hit
their flux limits already with only a few objects sampled, we propose
to exploit the new capabilities of WFC3 to perform the first ever
large-scale dynamical-compositional study of Kuiper Belt Objects
(KBOs) and their progeny to study the chemical, dynamical, and
collisional history of the region of the giant planets. The
sensitivity of the WFC3 observations will allow us to go up to two
magnitudes deeper than our ground based studies, allowing us the
capability of optimally selecting a target list for a large survey
rather than simply taking the few objects that can be measured, as we
have had to do to date. We have carefully constructed a sample of 120
objects which provides both overall breadth, for a general
understanding of these objects, plus a large enough number of objects
in the individual dynamical subclass to allow detailed comparison
between and within these groups. These objects will likely define the
core Kuiper Belt compositional sample for years to come. While we have
many specific results anticipated to come from this survey, as with
any project where the field is rich, our current knowledge level is
low, and a new instrument suddenly appears which can exploit vastly
larger segments of the population, the potential for discovery -- both
anticipated and not -- is extraordinary.

WFC3/IR 11631

Binary Brown Dwarfs and the L/T Transition

Brown dwarfs traverse spectral types M, L and T as their atmospheric
structure evolves and they cool into oblivion. This SNAPSHOT program
will obtain WFC3-IR images of 45 nearby late-L and early-T dwarfs to
investigate the nature of the L/T transition. Recent analyses have
suggested that a substantial proportion of late-L and early-T dwarfs
are binaries, comprised of an L dwarf primary and T dwarf secondary.
WFC3-IR observations will let us quantify this suggestion by expanding
coverage to a much larger sample, and permitting comparison of the L/T
binary fraction against ?normal? ultracool dwarfs. Only eight L/T
binaries are currently known, including several that are poorly
resolved: we anticipate at least doubling the number of resolved
systems. The photometric characteristics of additional resolved
systems will be crucial to constraining theoretical models of these
late-type ultracool dwarfs. Finally, our data will also be eminently
suited to searching for extremely low luminosity companions,
potentially even reaching the Y dwarf regime.

STIS/CCD/MA1/MA2 11616

The Disks, Accretion, and Outflows (DAO) of T Tau Stars

Classical T Tauri stars undergo magnetospheric accretion, power
outflows, and possess the physical and chemical conditions in their
disks to give rise to planet formation. Existing high resolution FUV
spectra verify that this spectral region offers unique diagnostics of
these processes, which have the potential to significantly advance our
understanding of the interaction of a star and its accretion disk. To
date the limited results are intriguing, with dramatic differences in
kinematic structure in lines ranging from C IV to H2 among the few
stars that have been observed. We propose to use HST/COS to survey the
disks, outflows, and accretion (the DAO) of 26 CTTS and 6 WTTS in the
FUV at high spectral resolution. A survey of this size is essential to
establish how properties of accretion shocks, winds and disk
irradiation depend on disk accretion rate. Specifically, our goals are
to (1) measure the radiation from and understand the physical
properties of the gas very near the accretion shock as a function of
accretion rate using emission line profiles of hot lines (C IV, Si IV,
N V, and He II); (2) measure the opacity, velocity, and temperature at
the base of the outflow to constrain outflow models using wind
absorption features; and (3) characterize the radiation incident on
disks and protoplanetary atmospheres using H2 line and continuum
emission and reconstructed bright Ly-alpha line emission.

WFC3/ACS/UVIS 11613

GHOSTS: Stellar Outskirts of Massive Spiral Galaxies

We propose to continue our highly successful GHOSTS HST survey of the
resolved stellar populations of nearby, massive disk galaxies using
SNAPs. These observations provide star counts and color-magnitude
diagrams 2-3 magnitudes below the tip of the Red Giant Branch of the
outer disk and halo 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.

This proposal will substantially improve our unique sampling of galaxy
outskirts. Our targets cover a range in galaxy mass, luminosity,
inclination, and morphology. As a function of these galaxy properties,
this survey provides: - the most extensive, systematic measurement of
radial light profiles and axial ratios of the diffuse stellar halos
and outer disks of spiral galaxies; - a comprehensive analysis of halo
metallicity distributions as function of galaxy type and position
within the galaxy; - an unprecedented study of the stellar metallicity
and age distribution in the outer disk regions where the disk
truncations occur; - the first comparative study of globular clusters
and their field stellar populations.

We will use these fossil records of the galaxy assembly process to
test halo formation models within the hierarchical galaxy formation
scheme.

ACS/WFC3 11599

Distances of Planetary Nebulae from SNAPshots of Resolved Companions

Reliable distances to individual planetary nebulae (PNe) in the Milky
Way are needed to advance our understanding of their spatial
distribution, birthrates, influence on galactic chemistry, and the
luminosities and evolutionary states of their central stars (CSPN).
Few PNe have good distances, however. One of the best ways to remedy
this problem is to find resolved physical companions to the CSPN and
measure their distances by photometric main-sequence fitting. We have
previously used HST to identify and measure probable companions to 10
CSPN, based on angular separations and statistical arguments only. We
now propose to use HST to re-observe 48 PNe from that program for
which additional companions are possibly present. We then can use the
added criterion of common proper motion to confirm our original
candidate companions and identify new ones in cases that could not
confidently be studied before. We will image the region around each
CSPN in the V and I bands, and in some cases in the B band. Field
stars that appear close to the CSPN by chance will be revealed by
their relative proper motion during the 13+ years since our original
survey, leaving only genuine physical companions in our improved and
enlarged sample. This study will increase the number of Galactic PNe
with reliable distances by 50 percent and improve the distances to PNe
with previously known companions.

WFC3/UVIS 11577

Opening New Windows on the Antennae with WFC3

We propose to use WFC3 to provide key observations of young star
clusters in "The Antennae" (NGC4038/39). Of prime importance is the
WFC3's ability to push the limiting UV magnitude FIVE mag deeper than
our previous WFPC2 observations. This corresponds to pushing the
limiting cluster mass from ~10**5 to ~10**3 solar masses for cluster
ages ~10**8 yrs. In addition, the much wider field of view of the WFC3
IR channel will allow us to map out both colliding disks rather than
just the Overlap Region between them. This will be especially
important for finding the youngest clusters that are still embedded in
their placental cocoons. The extensive set of narrow- band filters
will provide an effective means for determining the properties of
shocks, which are believed to be a primary triggering mechanism for
star formation. We will also use ACS in parallel with WFC3 to observe
portions of both the northern and southern tails at no additional
orbital cost. Finally, one additional primary WFC3 orbit will be used
to supplement exisiting HST observations of the star-forming "dwarf"
galaxy at the end of the southern tail. Hence, when completed we will
have full UBVI + H_alpha coverage (or more for the main galaxy) of
four different environments in the Antennae. In conjunction with the
extensive multi-wavelength database we have collected (both HST and
ground based) these observations will provide answers to fundamental
questions such as: How do these clusters form and evolve? How is star
formation triggered? How do star clusters affect the local and global
ISM, and the evolution of the galaxy as a whole? The Antennae galaxies
are the nearest example of a major disk--disk merger, and hence may
represent our best chance for understanding how mergers form
tremendous numbers of clusters and stars, both in the local universe
and during galaxy assembly at high redshift.

WFC3/ACS/UVIS/IR 11570

Narrowing in on the Hubble Constant and Dark Energy

A measurement of the Hubble constant to a precision of a few percent
would be a powerful aid to the investigation of the nature of dark
energy and a potent "end-to end" test of the present cosmological
model. In Cycle 15 we constructed a new streamlined distance ladder
utilizing high- quality type Ia supernova data and observations of
Cepheids with HST in the near-IR to minimize the dominant sources of
systematic uncertainty in past measurements of the Hubble constant and
reduce its total uncertainty to a little under 5%. Here we propose to
exploit this new route to reduce the remaining uncertainty by more
than 30%, translating into an equal reduction in the uncertainty of
the equation of state of dark energy. We propose three sets of
observations to reach this goal: a mosaic of NGC 4258 with WFC3 in
F160W to triple its sample of long period Cepheids, WFC3/F160W
observations of the 6 ideal SN Ia hosts to triple their samples of
Cepheids, and observations of NGC 5584 the host of a new SN Ia, SN
2007af, to discover and measure its Cepheids and begin expanding the
small set of SN Ia luminosity calibrations. These observations would
provide the bulk of a coordinated program aimed at making the
measurement of the Hubble constant one of the leading constraints on
dark energy.

STIS/CCD/MA2 11568

A SNAPSHOT Survey of the Local Interstellar Medium: New NUV
Observations of Stars with Archived FUV Observations

We propose to obtain high-resolution STIS E230H SNAP observations of
MgII and FeII interstellar absorption lines toward stars within 100
parsecs that already have moderate or high-resolution far- UV (FUV),
900-1700 A, observations available in the MAST Archive. Fundamental
properties, such as temperature, turbulence, ionization, abundances,
and depletions of gas in the local interstellar medium (LISM) can be
measured by coupling such observations. Due to the wide spectral range
of STIS, observations to study nearby stars also contain important
data about the LISM embedded within their spectra. However, unlocking
this information from the intrinsically broad and often saturated FUV
absorption lines of low-mass ions, (DI, CII, NI, OI), requires first
understanding the kinematic structure of the gas along the line of
sight. This can be achieved with high resolution spectra of high-mass
ions, (FeII, MgII), which have narrow absorption lines, and can
resolve each individual velocity component (interstellar cloud). By
obtaining short (~10 minute) E230H observations of FeII and MgII, for
stars that already have moderate or high-resolution FUV spectra, we
can increase the sample of LISM measurements, and thereby expand our
knowledge of the physical properties of the gas in our galactic
neighborhood. STIS is the only instrument capable of obtaining the
required high resolution data now or in the foreseeable future.

STIS/CCD 11567

Boron Abundances in Rapidly Rotating Early-B Stars

Models of rotation in early-B stars predict that rotationally driven
mixing should deplete surface boron abundances during the
main-sequence lifetime of many stars. However, recent work has shown
that many boron depleted stars are intrinsically slow rotators for
which models predict no depletion should have occurred, while
observations of nitrogen in some more rapidly rotating stars show less
mixing than the models predict. Boron can provide unique information
on the earliest stages of mixing in B stars, but previous surveys have
been biased towards narrow-lined stars because of the difficulty in
measuring boron abundances in rapidly rotating stars. The two targets
observed as part of our Cycle 13 SNAP program 10175, just before STIS
failed, demonstrate that it is possible to make useful boron abundance
measurements for early-B stars with Vsin(i) above 100 km/s. We propose
to extend that survey to a large enough sample of stars to allow
statistically significant tests of models of rotational mixing in
early-B stars.

WFC3/ACS/IR 11563

Galaxies at z~7-10 in the Reionization Epoch: Luminosity Functions to
0.2L* from Deep IR Imaging of the HUDF and HUDF05 Fields

The first generations of galaxies were assembled around redshifts
z~7-10+, just 500-800 Myr after recombination, in the heart of the
reionization of the universe. We know very little about galaxies in
this period. Despite great effort with HST and other telescopes, less
than ~15 galaxies have been reliably detected so far at z7,
contrasting with the ~1000 galaxies detected to date at z~6, just
200-400 Myr later, near the end of the reionization epoch. WFC3 IR can
dramatically change this situation, enabling derivation of the galaxy
luminosity function and its shape at z~7-8 to well below L*,
measurement of the UV luminosity density at z~7-8 and z~8-9, and
estimates of the contribution of galaxies to reionization at these
epochs, as well as characterization of their properties (sizes,
structure, colors). A quantitative leap in our understanding of early
galaxies, and the timescales of their buildup, requires a total sample
of ~100 galaxies at z~7-8 to ~29 AB mag. We can achieve this with 192
WFC3 IR orbits on three disjoint fields (minimizing cosmic variance):
the HUDF and the two nearby deep fields of the HUDF05. Our program
uses three WFC3 IR filters, and leverages over 600 orbits of existing
ACS data, to identify, with low contamination, a large sample of over
100 objects at z~7-8, a very useful sample of ~23 at z~8-9, and limits
at z~10. By careful placement of the WFC3 IR and parallel ACS
pointings, we also enhance the optical ACS imaging on the HUDF and a
HUDF05 field. We stress (1) the need to go deep, which is paramount to
define L*, the shape, and the slope alpha of the luminosity function
(LF) at these high redshifts; and (2) the far superior performance of
our strategy, compared with the use of strong lensing clusters, in
detecting significant samples of faint z~7-8 galaxies to derive their
luminosity function and UV ionizing flux. Our recent z~7.4 NICMOS
results show that wide-area IR surveys, even of GOODS-like depth,
simply do not reach faint enough at z~7-9 to meet the LF and UV flux
objectives. In the spirit of the HDF and the HUDF, we will waive any
proprietary period, and will also deliver the reduced data to STScI.
The proposed data will provide a Legacy resource of great value for a
wide range of archival science investigations of galaxies at redshifts
z~2-9. The data are likely to remain the deepest IR/optical images
until JWST is launched, and will provide sources for spectroscopic
followup by JWST, ALMA and EVLA.

WFC3/ACS/IR 11235

HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies
in the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared
selected galaxies exceeds that of optically selected galaxies. These
`luminous infrared galaxies' (LIRGs) are primarily interacting or
merging disk galaxies undergoing enhanced star formation and Active
Galactic Nuclei (AGN) activity, possibly triggered as the objects
transform into massive S0 and elliptical merger remnants. We propose
NICMOS NIC2 imaging of the nuclear regions of a complete sample of 88
L_IR 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised
Bright Galaxy Sample (RBGS: i.e., 60 micron flux density 5.24 Jy).
This sample is ideal not only in its completeness and sample size, but
also in the proximity and brightness of the galaxies. The superb
sensitivity and resolution of NICMOS NIC2 on HST enables a unique
opportunity to study the detailed structure of the nuclear regions,
where dust obscuration may mask star clusters, AGN, and additional
nuclei from optical view, with a resolution significantly higher than
possible with Spitzer IRAC. This survey thus provides a crucial
component to our study of the dynamics and evolution of IR galaxies
presently underway with Wide-Field, HST ACS/WFC3, and Spitzer IRAC
observations of these 88 galaxies. Imaging will be done with the F160W
filter (H-band) to examine as a function of both luminosity and merger
stage: (i) the luminosity and distribution of embedded star clusters,
(ii) the presence of optically obscured AGN and nuclei, (iii) the
correlation between the distribution of 1.6 micron emission and the
mid-IR emission as detected by Spitzer IRAC, (iv) the evidence of bars
or bridges that may funnel fuel into the nuclear region, and (v) the
ages of star clusters for which photometry is available via ACS/WFC3
observations. The NICMOS data, combined with the HST ACS, Spitzer, and
GALEX observations of this sample, will result in the most
comprehensive study of merging and interacting galaxies to date.

WFC3/IR 11189

Probing the Early Universe with GRBs

Cosmology is beginning to constrain the nature of the earliest stars
and galaxies to form in the Universe, but direct observation of
galaxies at z6 remains highly challenging due to their scarcity,
intrinsically small size, and high luminosity distance. GRB
afterglows, thanks to their extreme luminosities, offer the
possibility of circumventing these normal constraints by providing
redshifts and spectral information which couldn't be obtained through
direct observation of the host galaxies themselves. In addition, the
association of GRBs with massive stars means that they are an
indicator of star formation, and that their hosts are likely
responsible for a large proportion of the ionizing radiation during
that era. Our collaboration is conducting a campaign to rapidly
identify and study candidate very high redshift bursts, bringing to
bear a network of 2, 4 and 8m telescopes with near-IR instrumentation.
Swift has proven capable of detecting faint, distant GRBs, and
reporting accurate positions for many bursts in near real-time. Here
we propose to continue our HST program of targeting GRBs at z~6 and
above. HST is crucial to this endeavor, allowing us (a) to
characterize the basic properties, such as luminosity and color, and
in some cases morphologies, of the hosts, which is essential to
understanding these primordial galaxies and their relationship to
other galaxy populations; and (b) to monitor the late time afterglows
and hence compare them to lower-z bursts and test the use of GRBs as
standard candles.

NIC3/WFC3/IR 11153

The Physical Nature and Age of Lyman Alpha Galaxies

In the simplest scenario, strong Lyman alpha emission from high
redshift galaxies would indicate that stellar populations younger than
10 Myrs dominate the UV. This does not, however, constrain the stellar
populations older than 100 Myrs, which do not contribute to UV light.
Also, the Lyman alpha line can be boosted if the interstellar medium
is both clumpy and dusty. Different studies with small samples have
reached different conclusions about the presence of dust and old
stellar populations in Lyman alpha emitters. We propose HST-NICMOS and
Spitzer-IRAC photometry of 35 Lyman-alpha galaxies at redshift
4.5z6.5, in order to determine their spectral energy distribution
(SED) extending through rest-frame optical. This will allow us to
measure accurately (1) The total stellar mass in these objects,
including old stars which may have formed at redshifts (z 8) not
easily probed by any other means. (2) The dust extinction in the
rest-frame UV, and therefore a correction to their present
star-formation rates. Taken together, these two quantities will yield
the star-formation histories of Lyman alpha galaxies, which form fully
half of the known galaxies at z=4-6. They will tell us whether these
are young or old galaxies by straddling the 4000A break. Data from
NICMOS is essential for these compact and faint (i=25-26th magnitude
AB) high redshift galaxies, which are too faint for good near-IR
photometry from the ground.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

12172 - GSAcq(2,1,1) at 15:04:28, REAca(2,1,1) at 16:32:37 and
REAcq(2,1,1) at 18:08:30 failed to RGA control with Search Radius
Limit exceeded on FGS.

Observations affected: WFC3 185 - 193; Proposal ID# 11570.

12173 - GSAcq(2,1,1) at 024/21:51:07 and REAcq(2,1,1) at 22:50:03
acquired in fine lock backup on FGS 2.

Observations possibly affected: WFC3 231 - 235, 002; Proposal ID#
11631, 11908.

COMPLETED OPS REQUEST:

18802-0 - Null genslew for proposal 12053 - Slot 1 @ 023/1000z

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 20 19
FGS REAcq 30 28
OBAD with Maneuver 13 13

SIGNIFICANT EVENTS: (None)
 




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