HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5187
PERIOD
COVERED: 5am September 22 - 5am September 23, 2010 (DOY 265/09:00z-266/09:00z)
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
5
5
FGS
REAcq
8
8
OBAD with
Maneuver
7
7
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.
COS/NUV/FUV
11598
How
Galaxies Acquire their Gas: A Map of Multiphase Accretion and
Feedback in
Gaseous Galaxy Halos
We propose
to address two of the biggest open questions in galaxy
formation -
how galaxies acquire their gas and how they return it to the
IGM - with
a concentrated COS survey of diffuse multiphase gas in the
halos of
SDSS galaxies at z = 0.15 - 0.35. Our chief science goal is to
establish a
basic set of observational facts about the physical state,
metallicity,
and kinematics of halo gas, including the sky covering
fraction of
hot and cold material, the metallicity of infall and
outflow,
and correlations with galaxy stellar mass, type, and color -
all as a
function of impact parameter from 10 - 150 kpc. Theory suggests
that the
bimodality of galaxy colors, the shape of the luminosity
function,
and the mass-metallicity relation are all influenced at a
fundamental
level by accretion and feedback, yet these gas processes are
poorly
understood and cannot be predicted robustly from first
principles.
We lack even a basic observational assessment of the
multiphase
gaseous content of galaxy halos on 100 kpc scales, and we do
not know
how these processes vary with galaxy properties. This ignorance
is
presently one of the key impediments to understanding galaxy
formation
in general. We propose to use the high-resolution gratings
G130M and
G160M on the Cosmic Origins Spectrograph to obtain sensitive
column
density measurements of a comprehensive suite of multiphase ions
in the
spectra of 43 z < 1 QSOs lying behind 43 galaxies selected from
the Sloan
Digital Sky Survey. In aggregate, these sightlines will
constitute
a statistically sound map of the physical state and
metallicity
of gaseous halos, and subsets of the data with cuts on
galaxy
mass, color, and SFR will seek out predicted variations of gas
properties
with galaxy properties. Our interpretation of these data will
be aided by
state-of-the-art hydrodynamic simulations of accretion and
feedback,
in turn providing information to refine and test such models.
We will
also use Keck, MMT, and Magellan (as needed) to obtain optical
spectra of the
QSOs to measure cold gas with Mg II, and optical spectra
of the
galaxies to measure SFRs and to look for outflows. In addition to
our other
science goals, these observations will help place the Milky
Way's
population of multiphase, accreting High Velocity Clouds (HVCs)
into a
global context by identifying analogous structures around other
galaxies.
Our program is designed to make optimal use of the unique
capabilities
of COS to address our science goals and also generate a
rich
dataset of other absorption-line systems.
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.
FGS 12320
The Ages of
Globular Clusters and the Population II Distance Scale
Globular
clusters are the oldest objects in the universe whose age can
be
accurately determined. The dominant error in globular cluster age
determinations
is the uncertain Population II distance scale. We propose
to use FGS
1r to obtain parallaxes with an accuracy of 0.2
milliarcsecond
for 9 main sequence stars with [Fe/H] < -1.5. This will
determine
the absolute magnitude of these stars with accuracies of 0.04
to 0.06mag.
This data will be used to determine the distance to 24
metal-poor
globular clusters using main sequence fitting. These
distances
(with errors of 0.05 mag) will be used to determine the ages
of globular
clusters using the luminosity of the subgiant branch as an
age
indicator. This will yield absolute ages with an accuracy 5%, about
a factor of
two improvement over current estimates. Coupled with
existing
parallaxes for more metal-rich stars, we will be able to
accurately
determine the age for globular clusters over a wide range of
metallicities
in order to study the early formation history of the Milky
Way and
provide an independent estimate of the age of the universe.
The Hipparcos
database contains only 1 star with [Fe/H] < -1.4 and an
absolute
magnitude error less than 0.18 mag which is suitable for use in
main
sequence fitting. Previous attempts at main sequence fitting to
metal-poor
globular clusters have had to rely on theoretical
calibrations
of the color of the main sequence. Our HST parallax program
will remove
this source of possible systematic error and yield distances
to
metal-poor globular clusters which are significantly more accurate
than
possible with the current parallax data. The HST parallax data will
have errors
which are 10 times smaller than the current parallax data.
Using the
HST parallaxes, we will obtain main sequence fitting distances
to 11
globular clusters which contain over 500 RR Lyrae stars. This will
allow us to
calibrate the absolute magnitude of RR Lyrae stars, a
commonly
used Population II distance indicator.
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.
WFC3/UV
11605
Obtaining
the Missing Links in the Test of Very Low Mass Evolutionary
Models with
HST
We are
proposing for spatially resolved ACS+HRC observations of 11 very
low mass
binaries spanning late-M, L and T spectral types in order to
obtain
precise effective temperature measurements for each component.
All of our
targets are part of a program in which we are measuring
dynamical
masses of very low-mass binaries to an unprecedented precision
of 10% (or
better). However, without precise temperature measurements,
the full
scientific value of these mass measurements cannot be realized.
Together,
mass and temperature measurements will allow us to distinguish
between
brown dwarf evolutionary models that make different assumptions
about the
interior and atmospheric structure of these ultra-cool
objects.
While dynamical masses can be obtained from the ground in the
near-IR,
obtaining precise temperatures require access to optical data
which, for
these sub-arcsecond binaries, can only be obtained from space
with
Hubble.
WFC3/UV
12245
Orbital
Evolution and Stability of the Inner Uranian Moons
Nine
densely-packed inner moons of Uranus show signs of chaos and
orbital
instability over a variety of time scales. Many moons show
measureable
orbital changes within a decade or less. Long-term
integrations
predict that some moons could collide in less than one
million
years. One faint ring embedded in the system may, in fact, be
the debris
left behind from an earlier such collision. Meanwhile, the
nearby moon
Mab falls well outside the influence of the others but
nevertheless
shows rapid, as yet unexplained, changes in its orbit. It
is embedded
within a dust ring that also shows surprising variability. A
highly
optimized series of observations with WFC3 over the next three
cycles will
address some of the fundamental open questions about this
dynamically
active system: Do the orbits truly show evidence of chaos?
If so, over
what time scales? What can we say about the masses of the
moons
involved? What is the nature of the variations in Mab's orbit? Is
Mab's
motion predictable or random? Astrometry will enable us to derive
the orbital
elements of these moons with 10-km precision. This will be
sufficient
to study the year-by-year changes and, combined with other
data from
2003-2007, the decadal evolution of the orbits. The pairing of
precise
astrometry with numerical integrations will enable us to derive
new
dynamical constraints on the masses of these moons. Mass is the
fundamental
unknown quantity currently limiting our ability to reproduce
the interactions
within this system. This program will also capitalize
upon our
best opportunity for nearly 40 years to study the unexplained
variations
in Uranus's faint outer rings.
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
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
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.
-Lynn
Lynn F.
Bassford office#: 301-286-2876
Hubble Space Telescope
CHAMP Mission Operations Manager
CHAMP Flight Operations Team Manager
Lockheed Martin Mission Services (LMMS)