HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT #4920
PERIOD
COVERED: 5am August 28 - 5am August 31, 2009 (DOY 240/09:00z-243/09:00z)
OBSERVATIONS
SCHEDULED
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
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
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 (11909), will be
used
to generate the necessary superbias and superdark reference files
for
the calibration pipeline (CDBS).
STIS/CCD
11846
CCD
Bias Monitor-Part 1
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
Monitor
the darks for the STIS CCD.
FGS
11787
Dynamical
Masses and Radii of Four White Dwarf Stars
This
proposal uses the FGS1R in Trans mode to resolve a pair of double
degenerate
binary systems (WD1639+153 and WD 1818+26) in order to
determine
their orbital elements. In addition, the binaries and several
nearby
field stars are observed by FGS1R in Pos mode to establish the
local
inertial reference frame of each binary, as well as its parallax
and
proper motion. This will allow for a direct measurement of the
distance,
which yields the intrinsic luminosity, and when combined with
the
spectroscopic estimates of the T_eff, the radius of each of the four
WD
stars. When combined with the orbital elements, this leads to a
dynamical
mass measurement for each WD, and a four calibration points of
the
WD mass-radius relation.
ACS/WFC3
11782
Measuring
the Shape and Orientation of the Galactic Dark-Matter Halo
using
Hypervelocity Stars
We
propose to obtain high-resolution images of five hypervelocity stars
in
the Galactic halo in order to establish the first-epoch astrometric
frame
for them, as a part of a long- term program to measure precise
proper
motions. The origin of these recently discovered stars, all with
positive
radial velocities above 540 km/s, is consistent only with being
ejected
from the deep potential well of the massive black hole at the
Galactic
center. The deviations of their space motions from purely
radial
trajectories probe the departures from spherical symmetry of the
Galactic
potential, mainly due to the triaxiality of the dark-matter
halo.
Reconstructing the full three-dimensional space motion of the
hypervelocity
stars, through astrometric proper motions, provides a
unique
opportunity to measure the shape and orientation of the dark
halo.
The hypervelocity stars allow measurement of the potential up to
75
kpc from the center, independently of and at larger distances than
are
afforded by tidal streams of satellite galaxies such as the
Sagittarius
dSph galaxy. HVS3 may be associated with the LMC, rather
then
the Galactic center, and would therefore present a case for a
supermassive
black hole at the center of the LMC. We request one orbit
with
ACS/WFC for each of the five hypervelocity stars to establish their
current
positions relative to background galaxies. We will request a
repeated
observation of these stars in Cycle 17, which will conclusively
measure
the astrometric proper motions.
WFC3/UVIS
11732
The
Temperature Profiles of Quasar Accretion Disks
We
can now routinely measure the size of quasar accretion disks using
gravitational
microlensing of lensed quasars. At optical wavelengths we
observe
a size and scaling with black hole mass roughly consistent with
thin
disk theory but the sizes are larger than expected from the
observed
optical fluxes. One solution would be to use a flatter
temperature
profile, which we can study by measuring the wavelength
dependence
of the disk size over the largest possible wavelength
baseline.
Thus, to understand the size discrepancy and to probe closer
to
the inner edge of the disk we need to extend our measurements to UV
wavelengths,
and this can only be done with HST. For example, in the UV
we
should see significant changes in the optical/UV size ratio with
black
hole mass. We propose monitoring 5 lenses spanning a broad range
of
black hole masses with well-sampled ground based light curves,
optical
disk size measurements and known GALEX UV fluxes during Cycles
17
and 18 to expand from our current sample of two lenses. We would
obtain
5 observations of each target in each Cycle, similar to our
successful
strategy for the first two targets.
FGS
11704
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.
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
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
11594
A
WFC3 Grism Survey for Lyman Limit Absorption at z=2
We
propose to conduct a spectroscopic survey of Lyman limit absorbers at
redshifts
1.8 < z < 2.5, using WFC3 and the G280 grism. This proposal
intends
to complete an approved Cycle 15 SNAP program (#10878) which was
cut
short due to the ACS failure. We have selected 64 quasars at 2.3 < z
<
2.6 from the Sloan Digital Sky Survey Spectroscopic Quasar Sample, for
which
no BAL signature is found at the QSO redshift and no strong metal
absorption
lines are present at z > 2.3 along the lines of sight. The
survey
has three main observational goals. First, we will determine the
redshift
frequency dn/dz of the LLS over the column density range 16.0 <
log(NHI)
< 20.3 cm^-2. Second, we will measure the column density
frequency
distribution f(N) for the partial Lyman limit systems (PLLS)
over
the column density range 16.0 < log(NHI) < 17.5 cm^-2. Third, we
will
identify those sightlines which could provide a measurement of the
primordial
D/H ratio. By carrying out this survey, we can also help
place
meaningful constraints on two key quantities of cosmological
relevance.
First, we will estimate the amount of metals in the LLS using
the
f(N), and ground based observations of metal line transitions.
Second,
by determining f(N) of the PLLS, we can constrain the amplitude
of
the ionizing UV background at z~2 to a greater precision. This survey
is
ideal for a snapshot observing program, because the on-object
integration
times are all well below 30 minutes, and follow-up
observations
from the ground require minimal telescope time due to the
QSO
sample being bright.
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 followup by
JWST,
ALMA and EVLA.
COS
11480
COS
NUV Structural and Thermal Stability
The
goal of this program is to measure OTA-COS pointing jitter or
drifts,
over timescales of seconds to hours. In particular, our
priorities
are to test the level of OSM1 drift, thermal day-night
transitions
and orbital 'breathing'. Pointing-related thermal offsets
with
their related drifts during thermal settling will be overlayed upon
the
signatures of the other components of positional change. Three
different
instrumental configurations/transitions will be tested: NUV
and
FUV spectroscopy, and NUV imaging using MIRROR A. All with the PSA.
No
FP-POS motions, nor grating changes will be made during the
spectroscopy
in order to limit the variables contributing to any changes
in
position of the spectra.
ID:
COS 20(11480) & 35(11493) This in the NUV portion of this
experiment.
It was initially estimated to be a 6-orbit program, but has
been
expanded to 10 in order to improve the statistical sample of the
day-night/breathing
transitions.
ACS/WFC3
11465
ACS
CCD Monitoring and Calibration for WFC3
This
program is a smaller version of our routine CCD monitoring program,
designed
to run throughout SMOV, after which our regular Cycle 17 CAL
proposal
will begin. This program obtains the bias and dark frames
needed
to generate reference files for calibrating science data, and
allows
us to monitor detector noise and the growth of hot pixels.
WFC3/UVIS
11446
WFC3
UVIS Dark Current, Readnoise, and CTE
This
proposal obtains full-frame, four-amp readout bias and dark frames
at
regularly- spaced intervals throughout SMOV in order to assess and
monitor
dark current, bad (warm, hot, dead) pixels, and readnoise. In
addition,
a set of internals using the WFC3 calsystem are taken to
provide
a baseline CTE measurement. WFC3-33
WFC3/UVIS
11432
UVIS
Internal Flats
This
proposal will be used to assess the stability of the flat field
structure
for the UVIS detector. Flat fields will be obtained for all
filters
using the internal D2 and Tungsten lamps.
This
proposal corresponds to Activity Description ID WF19. It should
execute
only after the following proposals have executed: WF08 - 11421
WF09
- 11422 WF11 - 11424 WF15 - 11428
STIS20
11402
STIS-20
NUV MAMA Dark Monitor
The
STIS NUV-MAMA dark current is dominated by a phosphorescent glow
from
the detector window. Meta-stable states in this window are
populated
by cosmic ray impacts, which, days later, can be thermally
excited
to an unstable state from which they decay, emitting a UV
photon.
The equilibrium population of these meta-stable states is larger
at
lower temperatures; so warming up the detector from its cold safing
will
lead to a large, but temporary, increase in the dark current.
To
monitor the decay of this glow, and to determine the equilibrium dark
current
for Cycle 17, four 1380s NUV-MAMA ACCUM mode darks should be
taken
each week during the SMOV period. Once the observed dark current
has
reached an approximate equilibrium with the mean detector
temperature,
the frequency of this monitor can be reduced to one pair of
darks
per week.
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:
18692-0
- Update COS OSM1 G130M, G160M, and G140L focus positions in FSW
@240/17:41z
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSAcq
22
22
FGS
REAcq
21
21
OBAD
with Maneuver
12
12
SIGNIFICANT
EVENTS: (None)