HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5154
PERIOD
COVERED: 5am August 5 - 5am August 6, 2010 (DOY 217/09:00z-218/09:00z)
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
8
8
FGS
REAcq
6
6
OBAD
with Maneuver 6
6
SIGNIFICANT
EVENTS: (None)
OBSERVATIONS
SCHEDULED:
ACS/WFC3
11670
The
Host Environments of Type Ia Supernovae in the SDSS Survey
The
Sloan Digital Sky Survey Supernova Survey has discovered nearly 500
type
Ia supernovae and created a large, unique, and uniform sample of
these
cosmological tools. As part of a comprehensive study of the
supernova
hosts, we propose to obtain Hubble ACS images of a large
fraction
of these galaxies. Integrated colors and spectra will be
measured
from the ground, but we require high-resolution HST imaging to
provide
accurate morphologies and color information at the site of the
explosion.
This information is essential in determining the systematic
effects
of population age on type Ia supernova luminosities and
improving
their reliability in measuring dark energy. Recent studies
suggest
two populations of type Ia supernovae: a class that explodes
promptly
after star-formation and one that is delayed by billions of
years.
Measuring the star-formation rate at the site of the supernova
from
colors in the HST images may be the best way to differentiate
between
these classes.
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/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 z>7, 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 follow up by
JWST,
ALMA and EVLA.
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/ACS/IR
11731
Studying
Cepheid Systematics in M81: H-Band Observations
The
local value of the Hubble Constant remains one of the most important
constraints
in cosmology, but improving on the 10% accuracy of the HST
Key
Project is challenging. No improvements will be convincing until the
metallicity
dependence is well constrained and blending effects are
fully
understood. M81 and its dwarf companion Holmberg IX are superb
laboratories
for studying Cepheid systematics because they contain large
numbers
of bright Cepheids with a good spread in metallicity lying at a
common,
relatively close distance. We have identified 180 12<P< 70 day
Cepheids
in these two galaxies using the Large Binocular Telescope
(compared
to 30 in total by the KP), and will expand the sample further
in
2008-2009. We will use 10 orbits with WFC3/IR to obtain H-band images
of
100 Cepheids in M81 to add to the ACS/BVI calibrations we will obtain
from
archival data and 1 orbit with WFC3/UVIS to add B-band data for
Holmberg
IX. Four band BVIH photometry will allow us to flux calibrate,
estimate
extinction, measure metallicity effects and then check the
results
in detail. We can also examine blending effects on WFC3/IR data
in
a relatively nearby galaxy before it is applied to more distant
galaxies.
Our M81 sample is three times larger than the next best
sample,
that of NGC4258, and suffers less from blending because M81 is
at
half the distance, so it is an excellent laboratory for studying
Cepheid
systematics even if it lacks as precise a geometric distance as
NGC4258.
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/UVIS
11630
Monitoring
Active Atmospheres on Uranus and Neptune
We
propose Snapshot observations of Uranus and Neptune to monitor
changes
in their atmospheres on time scales of weeks and months, as we
have
been doing for the past seven years. Previous Hubble Space
Telescope
observations (including previous Snapshot programs 8634,
10170,
10534, and 11156), together with near-IR images obtained using
adaptive
optics on the Keck Telescope, reveal both planets to be dynamic
worlds
which change on time scales ranging from hours to (terrestrial)
years.
Uranus equinox occurred in December 2007, and the northern
hemisphere
is becoming fully visible for the first time since the early
1960s.
HST observations during the past several years (Hammel et al.
2005,
Icarus 175, 284 and references therein) have revealed strongly
wavelength-dependent
latitudinal structure, the presence of numerous
visible-wavelength
cloud features in the northern hemisphere, at least
one
very long- lived discrete cloud in the southern hemisphere, and in
2006
the first clearly defined dark spot seen on Uranus. Long term
ground-based
observations (Lockwood and Jerzekiewicz, 2006, Icarus 180,
442;
Hammel and Lockwood 2007, Icarus 186, 291) reveal seasonal
brightness
changes that seem to demand the appearance of a bright
northern
polar cap within the next few years. Recent HST and Keck
observations
of Neptune (Sromovsky et al. 2003, Icarus 163, 256 and
references
therein) show a general increase in activity at south
temperate
latitudes until 2004, when Neptune returned to a rather
Voyager-like
appearance with discrete bright spots rather than active
latitude
bands. Further Snapshot observations of these two dynamic
planets
will elucidate the nature of long-term changes in their zonal
atmospheric
bands and clarify the processes of formation, evolution, and
dissipation
of discrete albedo features.
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).