HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5182
PERIOD
COVERED: 5am September 15 - 5am September 16, 2010 (DOY 258/09:00z-259/09:00z)
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
12407
- GSAcq(2,1,1) at 259/02:27:06z and REAcq(2,1,1) at 259/03:54:49z both failed
due to search radius limit exceeded on FGS2
Observations affected: WFC3 90 proposal ID#12234; STIS 67 proposal
ID#11999.
HSTAR
FOR DOY 242:
12404
- GSAcq(1,2,1) at 242/15:42:17z initially received a scan step
limit exceeded flag on FGS1. The second attempt was successful and
the
acquisition succeeded.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS
GSAcq
12
11
FGS
REAcq
05
04
OBAD
with Maneuver 06 06
SIGNIFICANT
EVENTS: (None)
OBSERVATIONS
SCHEDULED:
ACS/WFC
11996
CCD
Daily Monitor (Part 3)
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 308 orbits (19.25 weeks) from 21 June 2010 to 1 November
2010.
ACS/WFC
12210
SLACS
for the Masses: Extending Strong Lensing to Lower Masses and
Smaller
Radii
Strong
gravitational lensing provides the most accurate possible
measurement
of mass in the central regions of early-type galaxies
(ETGs).
We propose to continue the highly productive Sloan Lens ACS
(SLACS)
Survey for strong gravitational lens galaxies by observing a
substantial
fraction of 135 new ETG gravitational-lens candidates with
HST-ACS
WFC F814W Snapshot imaging. The proposed target sample has been
selected
from the seventh and final data release of the Sloan Digital
Sky
Survey, and is designed to complement the distribution of previously
confirmed
SLACS lenses in lens-galaxy mass and in the ratio of Einstein
radius
to optical half-light radius. The observations we propose will
lead
to a combined SLACS sample covering nearly two decades in mass,
with
dense mapping of enclosed mass as a function of radius out to the
half-light
radius and beyond. With this longer mass baseline, we will
extend
our lensing and dynamical analysis of the mass structure and
scaling
relations of ETGs to galaxies of significantly lower mass, and
directly
test for a transition in structural and dark-matter content
trends
at intermediate galaxy mass. The broader mass coverage will also
enable
us to make a direct connection to the structure of well-studied
nearby
ETGs as deduced from dynamical modeling of their line-of-sight
velocity
distribution fields. Finally, the combined sample will allow a
more
conclusive test of the current SLACS result that the intrinsic
scatter
in ETG mass-density structure is not significantly correlated
with
any other galaxy observables. The final SLACS sample at the
conclusion
of this program will comprise approximately 130 lenses with
known
foreground and background redshifts, and is likely to be the
largest
confirmed sample of strong-lens galaxies for many years to come.
COS/NUV/FUV/STIS/CCD/MA1
11692
The
LMC as a QSO Absorption Line System
We
propose to obtain high resolution, high signal-to-noise observations
of
QSOs behind the Large Magellanic Clouds. These QSOs are situated
beyond
the star forming disk of the galaxy, giving us the opportunity to
study
the distribution of metals and energy in regions lacking
significant
star formation. In particular, we will derive the
metallicities
and study the ionization characteristics of LMC gas at
impact
parameters 3-17 kpc. We will compare our results with high-z QSO
absorption
line systems.
STIS/CCD
11845
CCD
Dark Monitor Part 2
Monitor
the darks for the STIS CCD.
STIS/CCD
11847
CCD
Bias Monitor-Part 2
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
11999
JWST
Calibration from a Consistent Absolute Calibration of Spitzer &
Hubble
Recently,
Gordon, Bohlin, et al. submitted a successful Spitzer proposal
for
cross calibration of HST and Spitzer. The cross-calibration targets
are
stars in three categories: WDs, A-stars, and G-stars. Traditionally,
IR
flux standards are extrapolations of stellar models that are tied to
absolute
fluxes at shorter wavelengths. HST absolute flux standards are
among
the best available with a solid basis that uses pure hydrogen
models
of hot WD stars for the SED slopes and is tied to Vega at 5556A
via
precise Landolt V-band photometry. Consistently matching models to
our
three categories of HST observations along with Spitzer photometry
and
the few existing absolute IR flux determinations will provide a
solid
basis for JWST flux calibration over its 0.8-30micron range. The
goal
of this proposal is to complete the HST observations of the set of
HST/Spitzer
cross-calibration stars. Using a variety of standard stars
with
three different spectral types will ensure that the final
calibration
is not significantly affected by systematic uncertainties.
STIS/CCD/MA
11668
Cosmo-chronometry
and Elemental Abundance Distribution of the Ancient
Star
HE1523-0901
We
propose to obtain near-UV HST/STIS spectroscopy of the extremely
metal-poor,
highly r-process-enhanced halo star HE 1523-0901, in order
to
produce the most complete abundance distribution of the heaviest
stable
elements, including platinum, osmium, and lead. These HST
abundance
data will then be used to estimate the initial abundances of
the
long-lived radioactive elements thorium and uranium, and by
comparison
with their observed abundances, enable an accurate age
determination
of this ancient star. The use of radioactive chronometers
in
stars provides an independent lower limit on the age of the Galaxy,
which
can be compared with alternative limits set by globular clusters
and
by analysis from WMAP. Our proposed observations of HE1523-0901 will
also
provide significant new information about the early chemical
history
of the Galaxy, specifically, the nature of the first generations
of
stars and the types of nucleosynthetic processes that occurred at the
onset
of Galactic chemical evolution.
WFC3/ACS/IR
11840
Identifying
the Host Galaxies for Optically Dark Gamma-Ray Bursts
We
propose to use the high spatial resolution of Chandra to obtain
precise
positions for a sample of Gamma-Ray Bursts (GRBs) with no
optical
afterglows, where the optical light is suppressed relative to
the
X-ray flux. These bursts are likely to be highly obscured and may
have
different environments from the optically bright GRBs. Our Chandra
observations
will (unlike Swift XRT positions) allow for the unique
identification
of a host galaxy. To locate these host galaxies we will
follow
up our Chandra positions with deep optical and IR observations
with
HST. The ultimate aim is to understand any differences between the
host
galaxies of optically dark and bright GRBs, and how these affect
the
use of GRBs as tracers of starformation and galaxy evolution at high
redshift.
WFC3/IR
12265
Determining
the Physical Nature of a Unique Giant Lya Emitter at z=6.595
We
propose deep WFC3/IR imaging for a giant Lya emitter (LAE) with a
Keck
spectroscopic redshift of z=6.595 discovered by extensive
narrow-band
imaging with Subaru in the SXDS-UKIDSS/UDS field. This
remarkable
object is unique in many respects including its large stellar
mass
and luminous nebula which extends over 17 kpc; no equivalent source
has
been found in other surveys. The nature of this rare object is
unclear.
Fundamental to progress is determining the origin of star
formation
in such an early massive object; if the age of the stellar
population
is short we are likely witnessing a special moment in the
formation
history of a massive galaxy. The heating source for the nebula
is
also unclear; options include intense star formation, the infall of
cold
gas onto a dark halo or shock heating from a merger. We will take
deep
broad-band (F125W and F160W) images and an intermediate-band
(F098M)
image which will be analyzed in conjunction with ultra-deep IRAC
3.6
and 4.5 micron data being taken by the Spitzer/SEDS project. These
data
will enable us to constrain the star formation rate and stellar
age.
Moreover, the UV continuum morphology and Lya-line distribution
will
be investigated for evidence of a major merger, cold accretion, or
hot
bubbles associated with outflows. We will address the physical
origin
of the remarkable object observed at an epoch where massive
galaxies
are thought to begin their assembly.
WFC3/IR
12307
A
public SNAPSHOT Survey of Gamma-ray Burst Host Galaxies
We
propose to conduct a public infrared survey of the host galaxies of
Swift
selected gamma-ray bursts (GRBs) at z<3. By obtaining deep,
diffraction
limited imaging in the IR we will complete detections for
the
host galaxies, and in concert with our extensive ground based
afterglow
and host programmes will compile a detailed catalog of the
properties
of high-z galaxies selected by GRBs. In particular these
observations
will enable us to study the colours, luminosities and
morphologies
of the galaxies. This in turn informs studies of the nature
of
the progenitors and the role of GRBs as probes of star formation
across
cosmic history. Ultimately it provides a product of legacy value
which
will greatly complement further studies with next generation
facilities
such as ALMA and JWST.
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/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).
WFC3/UVIS
11907
UVIS
Cycle 17 Contamination Monitor
The
UV throughput of WFC3 during Cycle 17 is monitored via weekly
standard
star observations in a subset of key filters covering 200-600nm
and
F606W, F814W as controls on the red end. The data will provide a
measure
of throughput levels as a function of time and wavelength,
allowing
for detection of the presence of possible contaminants.
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
11912
UVIS
Internal Flats
This
proposal will be used to assess the stability of the flat field
structure
for the UVIS detector throughout the 15 months of Cycle 17.
The
data will be used to generate on-orbit updates for the delta-flat
field
reference files used in the WFC3 calibration pipeline, if
significant
changes in the flat structure are seen.
WFC3/UVIS
11914
UVIS
Earth Flats
This
program is an experimental path finder for Cycle 18 calibration.
Visible-wavelength
flat fields will be obtained by observing the dark
side
of the Earth during periods of full moon illumination. The
observations
will consist of full-frame streaked WFC3 UVIS imagery: per
22-
min total exposure time in a single "dark-sky" orbit, we anticipate
collecting
7000 e/pix in F606W or 4500 e/pix in F814W. To achieve
Poisson
S/N > 100 per pixel, we require at least 2 orbits of F606W and 3
orbits
of F814W.
For
UVIS narrowband filters, exposures of 1 sec typically do not
saturate
on the sunlit Earth, so we will take sunlit Earth flats for
three
of the more-commonly used narrowband filters in Cycle 17 plus the
also-popular
long-wavelength quad filters, for which we get four filters
at
once.
Why
not use the Sunlit Earth for the wideband visible-light filters? It
is
too bright in the visible for WFC3 UVIS minimum exposure time of 0.5
sec.
Similarly, for NICMOS the sunlit-Earth is too bright which
saturates
the detector too quickly and/or induces abnormal behaviors
such
as super-shading (Gilmore 1998, NIC 098-011). In the narrowband
visible
and broadband near- UV its not too bright (predictions in Cox et
al.
1987 "Standard Astronomical Sources for HST: 6. Spatially Flat
Fields."
and observations in ACS Program 10050).
Other
possibilities? Cox et al.'s Section II.D addresses many other
possible
sources for flat fields, rejecting them for a variety of
reasons.
A remaining possibility would be the totally eclipsed moon.
Such
eclipses provide approximately 2 hours (1 HST orbit) of opportunity
per
year, so they are too rare to be generically useful. An advantage of
the
moon over the Earth is that the moon subtends less than 0.25 square
degree,
whereas the Earth subtends a steradian or more, so scattered
light
and light potentially leaking around the shutter presents
additional
problems for the Earth. Also, we're unsure if HST can point
180
deg from the Sun.
WFC3/UVIS/IR
11700
Bright
Galaxies at z>7.5 with a WFC3 Pure Parallel Survey
The
epoch of reionization represents a special moment in the history of
the
Universe as it is during this era that the first galaxies and star
clusters
are formed. Reionization also profoundly affects the
environment
where subsequent generations of galaxies evolve. Our
overarching
goal is to test the hypothesis that galaxies are responsible
for
reionizing neutral hydrogen. To do so we propose to carry out a pure
parallel
WFC3 survey to constrain the bright end of the redshift z>7.5
galaxy
luminosity function on a total area of 176 arcmin^2 of sky.
Extrapolating
the evolution of the luminosity function from z~6, we
expect
to detect about 20 Lyman Break Galaxies brighter than M_* at z~8
significantly
improving the current sample of only a few galaxies known
at
these redshifts. Finding significantly fewer objects than predicted
on
the basis of extrapolation from z=6 would set strong limits to the
brightness
of M_*, highlighting a fast evolution of the luminosity
function
with the possible implication that galaxies alone cannot
reionize
the Universe. Our observations will find the best candidates
for
spectroscopic confirmation, that is bright z>7.5 objects, which
would
be missed by small area deeper surveys. The random pointing nature
of
the program is ideal to beat cosmic variance, especially severe for
luminous
massive galaxies, which are strongly clustered. In fact our
survey
geometry of 38 independent fields will constrain the luminosity
function
like a contiguous single field survey with two times more area
at
the same depth. Lyman Break Galaxies at z>7.5 down to m_AB=26.85 (5
sigma)
in F125W will be selected as F098M dropouts, using three to five
orbits
visits that include a total of four filters (F606W, F098M, F125W,
F160W)
optimized to remove low-redshift interlopers and cool stars. Our
data
will be highly complementary to a deep field search for high-z
galaxies
aimed at probing the faint end of the luminosity function,
allowing
us to disentangle the degeneracy between faint end slope and
M_*
in a Schechter function fit of the luminosity function. We waive
proprietary
rights for the data. In addition, we commit to release the
coordinates
and properties of our z>7.5 candidates within one month from
the
acquisition of each field.