HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5168
PERIOD
COVERED: 5am August 25 - 5am August 26, 2010 (DOY 237/09:00z-238/09:00z)
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:
18887-0
- Install COS CS FSW 4.11 @ 237/1542z
COMPLETED
OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS
GSAcq 05
05
FGS
REAcq
10
10
OBAD
with Maneuver 05
05
SIGNIFICANT
EVENTS:
COS
FSW 4.11 was successfully installed and verified by the FSW team at 237/15:42.
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.
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/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.
WFC3/IR
11694
Mapping
the Interaction Between High-Redshift Galaxies and the
Intergalactic
Environment
With
the commissioning of the high-throughput large-area camera WFC3/IR,
it
is possible for the first time to undertake an efficient survey of
the
rest-frame optical morphologies of galaxies at the peak epoch of
star
formation in the universe. We therefore propose deep WFC3/IR
imaging
of over 320 spectroscopically confirmed galaxies between
redshift
1.6 < z < 3.4 in well-studied fields which lie along the line
of
sight to bright background QSOs. The spectra of these bright QSOs
probe
the IGM in the vicinity of each of the foreground galaxies along
the
line of sight, providing detailed information on the physical state
of
the gas at large galactocentric radii. In combination with our
densely
sampled UV/IR spectroscopy, stellar population models, and
kinematic
data in these fields, WFC3/IR imaging data will permit us to
construct
a comprehensive picture of the structure, dynamics, and star
formation
properties of a large population of galaxies in the early
universe
and their effect upon their cosmological environment.
WFC3/IR
11708
Determining
the Sub-stellar IMF in the Most Massive Young Milky Way
Cluster,
Westerlund 1
Despite
over 50 years of active research, a key question in galactic
astronomy
remains unanswered: is the initial mass function (IMF) of
stars
and sub-stellar objects universal, or does it depend on initial
conditions?
The answer has profound consequences for the evolution of
galaxies
as well as a predictive theory of star formation. Work to date
suggests
that certain environments (high densities, e.g. Elmegreen 2004;
low
metallicity, e.g. Larson 2005) should produce a top-heavy IMF, and
there
are hints from unresolved star-bursts that this might be the case.
Yet,
there is no clear evidence for an IMF that differs from that
characterizing
the Galactic field stars in a resolved stellar population
down
to one solar mass. Westerlund 1 is the most massive young star
cluster
known in the Milky Way. With an estimated mass of 5x10^4 Msun,
an
age of 3-5 Myr, and located at a distance of 3-4 kpc, it presents a
unique
opportunity to test whether the IMF in such a cluster deviates
from
the norm well down into the brown dwarf regime. We propose WFC3
near-IR
imaging to probe the IMF down to 40 Jupiter masses. The data
will
enable use to: 1) provide a stringent test of the universality of
the
IMF under conditions approximating those of star-bursts; 2) search
for
primordial or dynamic mass segregation in the clusters; and 3)
assess
whether the cluster is likely to remain bound (as a massive open
cluster)
or disperse into the field. We will obtain images in the F125W,
F160W,
and F139M filters. The F139M filter covers a strong water
absorption
feature and the color F125W/F139M is a powerful temperature
diagnostic
in the range 2800-4000 K. This information will enable us to:
a)
confirm membership for low mass stars suspected on the basis of their
position
in the color-magnitude diagram; b) place the members in the HR
diagram;
and c) estimate the masses and ages of cluster members for
low-mass
stars and sub-stellar objects. This new capability offered with
the
WFC3 (through a novel combination of filter complement, high spatial
resolution,
and large field of view) will enable us to make a
fundamental
test of whether the IMF is universal on a unique resolved
stellar
population, as well as assess the clusters structure, dynamics,
and
ultimate fate.
WFC3/IR
11926
IR
Zero Points
We
will measure and monitor the zeropoints through the IR filters using
observations
of the white dwarf standard stars, GD153, GD71 and GD191B2B
and
the solar analog standard star, P330E. Data will be taken monthly
during
Cycle 17. Observations of the star cluster, NGC 104, are made
twice
to check color transformations. We expect an accuracy of 2% in the
wide
filter zeropoints relative to the HST photometric system, and 5% in
the
medium- and narrow-band filters.
WFC3/IR
11928
WFC3/IR
Low-Frequency Flat and Geometric Distortion
Multiple
observations of globular cluster Omega Cen at multiple infrared
wavelengths
of IR detector will be used to derive filter dependency of
low-frequency
sensitivity (L_flat fields) across of IR detector and its
time
variation. Additionally, the same data will be also used to derive
filter-dependant
geometric distortion of the detector and its
time-dependency.
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
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.