HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5078
PERIOD
COVERED: 5am April 19 - 5am April 20, 2010 (DOY 109/09:00z-110/09:00z)
OBSERVATIONS
SCHEDULED
ACS/WFC
11995
CCD
Daily Monitor (Part 2)
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 320 orbits (20 weeks) from 1 February 2010 to 20 June
2010.
COS/FUV
11895
FUV
Detector Dark Monitor
Monitor
the FUV detector dark rate by taking long science exposures
without
illuminating the detector. The detector dark rate and spatial
distribution
of counts will be compared to pre-launch and SMOV data in
order
to verify the nominal operation of the detector. Variations of
count
rate as a function of orbital position will be analyzed to find
dependence
of dark rate on proximity to the SAA. Dependence of dark rate
as
function of time will also be tracked.
COS/FUV
11897
FUV
Spectroscopic Sensitivity Monitoring
The
purpose of this proposal is to monitor sensitivity in each FUV
grating
mode to detect any changes due to contamination or other causes.
COS/FUV/STIS/CCD/MA1
11592
Testing
the Origin(s) of the Highly Ionized High-Velocity Clouds: A
Survey
of Galactic Halo Stars at z>3 kpc
Cosmological
simulation predicts that highly ionized gas plays an
important
role in the formation and evolution of galaxies and their
interplay
with the intergalactic medium. The NASA HST and FUSE missions
have
revealed high-velocity CIV and OVI absorption along extragalactic
sightlines
through the Galactic halo. These highly ionized high-velocity
clouds
(HVCs) could cover 85% of the sky and have a detection rate
higher
than the HI HVCs. Two competing, equally exciting, theories may
explain
the origin of these highly ionized HVCs: 1) the "Galactic"
theory,
where the HVCs are the result of feedback processes and trace
the
disk-halo mass exchange, perhaps including the accretion of matter
condensing
from an extended corona; 2) the "Local Group" theory, where
they
are part of the local warm-hot intergalactic medium, representing
some
of the missing baryonic matter of the Universe. Only direct
distance
determinations can discriminate between these models. Our group
has
found that some of these highly ionized HVCs have a Galactic origin,
based
on STIS observations of one star at z<5.3 kpc. We propose an HST
FUV
spectral survey to search for and characterize the high velocity NV,
CIV,
and SiIV interstellar absorption toward 24 stars at much larger
distances
than any previous searches (4<d<21 kpc, 3<|z|<13 kpc). COS
will
provide atomic to highly ionized species (e.g.,OI, CII, CIV, SiIV)
that
can be observed at sufficient resolution (R~22, 000) to not only
detect
these highly ionized HVCs but also to model their properties and
understand
their physics and origins. This survey is only possible
because
of the high sensitivity of COS in the FUV spectral range.
COS/NUV
11894
NUV
Detector Dark Monitor
The
purpose of this proposal is to measure the NUV detector dark rate by
taking
long science exposures with no light on the detector. The
detector
dark rate and spatial distribution of counts will be compared
to
pre-launch and SMOV data in order to verify the nominal operation of
the
detector. Variations of count rate as a function of orbital position
will
be analyzed to find dependence of dark rate on proximity to the
SAA.
Dependence of dark rate as function of time will also be tracked.
S/C
12046
COS
FUV DCE Memory Dump
Whenever
the FUV detector high voltage is on, count rate and current
draw
information is collected, monitored, and saved to DCE memory. Every
10
msec the detector samples the currents from the HV power supplies
(HVIA,
HVIB) and the AUX power supply (AUXI). The last 1000 samples are
saved
in memory, along with a histogram of the number of occurrences of
each
current value.
In
the case of a HV transient (known as a "crackle" on FUSE), where one
of
these currents exceeds a preset threshold for a persistence time, the
HV
will shut down, and the DCE memory will be dumped and examined as
part
of the recovery procedure. However, if the current exceeds the
threshold
for less than the persistence time (a "mini-crackle" in FUSE
parlance),
there is no way to know without dumping DCE memory. By
dumping
and examining the histograms regularly, we will be able to
monitor
any changes in the rate of "mini-crackles" and thus learn
something
about the state of the detector.
STIS/CC
11845
CCD
Dark Monitor Part 2
Monitor
the darks for the STIS CCD.
STIS/CC
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/CC
12078
Verification
of Adjustment to Two STIS MSM Positions
Two
STIS CCD CENWAVE positions (G430M 5216 & G750M 6094) project onto
the
detector at a row that differs significantly from the nominal
position
near the center of the detector. This proposal will test the
MSM
updates to properly center these positions.
STIS/CCD
11849
STIS
CCD Hot Pixel Annealing
This
purpose of this activity is to repair radiation induced hot pixel
damage
to the STIS CCD by warming the CCD to the ambient instrument
temperature
and annealing radiation-damaged pixels.
Radiation
damage creates hot pixels in the STIS CCD Detector. Many of
these
hot pixels can be repaired by warming the CCD from its normal
operating
temperature near -83 deg. C to the ambient instrument
temperature
(~ +5 deg. C) for several hours. The number of hot pixels
repaired
is a function of annealing temperature. The effectiveness of
the
CCD hot pixel annealing process is assessed by measuring the dark
current
behavior before and after annealing and by searching for any
window
contamination effects.
WFC3/ACS/IR
11600
Star
Formation, Extinction, and Metallicity at 0.7<z<1.5: H-Alpha Fluxes
and
Sizes from a Grism Survey of GOODS-N
The
global star formation rate (SFR) is ~10x higher at z=1 than today.
This
could be due to drastically elevated SFR in some fraction of
galaxies,
such as mergers with central bursts, or a higher SFR across
the
board. Either means that the conditions in z=1 star forming galaxies
could
be quite different from local objects. The next step beyond
measuring
the global SFR is to determine the dependence of SFR,
obscuration,
metallicity, and size of the star-forming region on galaxy
mass
and redshift. However, SFR indicators at z=1 typically apply local
calibrations
for UV, [O II] and far-IR, and do not agree with each other
on
a galaxy-by-galaxy basis. Extinction, metallicity, and dust
properties
cause uncontrolled offsets in SFR calibrations. The great
missing
link is Balmer H-alpha, the most sensitive probe of SFR. We
propose
a slitless WFC3/G141 IR grism survey of GOODS-N, at 2
orbits/pointing.
It will detect Ha+[N II] emission from 0.7<z<1.5, to
L(Ha)
= 1.7 x 10^41 erg/sec at z=1, measuring H-alpha fluxes and sizes
for
> 600 galaxies, and a small number of higher-redshift emitters. This
will
produce: an emission-line redshift survey unbiased by magnitude and
color
selection; star formation rates as a function of galaxy
properties,
e.g. stellar mass and morphology/mergers measured by ACS;
comparisons
of SFRs from H-alpha to UV and far-IR indicators;
calibrations
of line ratios of H-alpha to important nebular lines such
as
[O II] and H-beta, measuring variations in metallicity and extinction
and
their effect on SFR estimates; and the first measurement of scale
lengths
of the H-alpha emitting, star- forming region in a large sample
of
z~1 sources.
WFC3/ACS/UVIS/IR
11570
Narrowing
in on the Hubble Constant and Dark Energy
A
measurement of the Hubble constant to a precision of a few percent
would
be a powerful aid to the investigation of the nature of dark
energy
and a potent "end-to end" test of the present cosmological model.
In
Cycle 15 we constructed a new streamlined distance ladder utilizing
high-
quality type Ia supernova data and observations of Cepheids with
HST
in the near-IR to minimize the dominant sources of systematic
uncertainty
in past measurements of the Hubble constant and reduce its
total
uncertainty to a little under 5%. Here we propose to exploit this
new
route to reduce the remaining uncertainty by more than 30%,
translating
into an equal reduction in the uncertainty of the equation
of
state of dark energy. We propose three sets of observations to reach
this
goal: a mosaic of NGC 4258 with WFC3 in F160W to triple its sample
of
long period Cepheids, WFC3/F160W observations of the 6 ideal SN Ia
hosts
to triple their samples of Cepheids, and observations of NGC 5584
the
host of a new SN Ia, SN 2007af, to discover and measure its Cepheids
and
begin expanding the small set of SN Ia luminosity calibrations.
These
observations would provide the bulk of a coordinated program aimed
at
making the measurement of the Hubble constant one of the leading
constraints
on dark energy.
WFC3/IR
11719
A
Calibration Database for Stellar Models of Asymptotic Giant Branch
Stars
Studies
of galaxy formation and evolution rely increasingly on the
interpretation
and modeling of near-infrared observations. At these
wavelengths,
the brightest stars are intermediate mass asymptotic giant
branch
(AGB) stars. These stars can contribute nearly 50% of the
integrated
luminosity at near infrared and even optical wavelengths,
particularly
for the younger stellar populations characteristic of
high-redshift
galaxies (z>1). AGB stars are also significant sources of
dust
and heavy elements. Accurate modeling of AGB stars is therefore of
the
utmost importance.
The
primary limitation facing current models is the lack of useful
calibration
data. Current models are tuned to match the properties of
the
AGB population in the Magellanic Clouds, and thus have only been
calibrated
in a very narrow range of sub-solar metallicities.
Preliminary
observations already suggest that the models are
overestimating
AGB lifetimes by factors of 2-3 at lower metallicities.
At
higher (solar) metallicities, there are no appropriate observations
for
calibrating the models.
We
propose a WFC3/IR SNAP survey of nearby galaxies to create a large
database
of AGB populations spanning the full range of metallicities and
star
formation histories. Because of their intrinsically red colors and
dusty
circumstellar envelopes, tracking the numbers and bolometric
fluxes
of AGB stars requires the NIR observations we propose here. The
resulting
observations of nearby galaxies with deep ACS imaging offer
the
opportunity to obtain large (100-1000's) complete samples of AGB
stars
at a single distance, in systems with well-constrained star
formation
histories and metallicities.
WFC3/UV
12077
Monitoring
the Aftermath of an Asteroid Impact Event
Our
Director's Discretionary program (GO-12053) to image the newly
discovered
object P/2010 A2 executed successfully on 2010 Jan 25 and 29
with
spectacular results. Hubble has apparently borne witness to the
first
detection of a collision in the asteroid belt. Hubble imaging with
the
WFC3 has revealed an object unlike anything ever seen before and
with
details impossible to detect with any other facility. We request 6
more
orbits of Hubble time (1 orbit every 20 days over the next few
months,
until the object enters Hubble's solar exclusion zone in
late-June
2010) to monitor the evolution of this remarkable object and
further
clarify the nature of this event. These observations may usher
in
a new era of searching for and characterizing collisional events
within
the asteroid belt.
WFC3/UVIS
11565
A
Search for Astrometric Companions to Very Low-Mass, Population II
Stars
We
propose to carry out a Snapshot search for astrometric companions in
a
subsample of very low-mass, halo subdwarfs identified within 120
parsecs
of the Sun. These ultra-cool M subdwarfs are local
representatives
of the lowest-mass H burning objects from the Galactic
Population
II. The expected 3-4 astrometric doubles that will be
discovered
will be invaluable in that they will be the first systems
from
which gravitational masses of metal-poor stars at the bottom of the
main
sequence can be directly measured.
WFC3/UVIS
11650
Mutual
Orbits, Colors, Masses, and Bulk Densities of 3 Cold Classical
Trans-Neptunian
Binaries
Many
Trans-Neptunian Objects (TNOs) have been found to be binary or
multiple
systems. As in other astrophysical settings, Trans-Neptunian
Binaries
(TNBs) offer uniquely valuable information. Their mutual orbits
allow
the direct determination of their system masses, perhaps the most
fundamental
physical quantity of any astronomical object. Their
frequency
of occurrence and dynamical characteristics provide clues to
formation
conditions and evolution scenarios affecting both the binaries
and
their single neighbors. Combining masses with sizes, bulk densities
can
be measured. Densities constrain bulk composition and internal
structure,
key clues to TNO origins and evolution over time. Several TNB
bulk
densities have been determined, hinting at interesting trends. But
none
of them belongs to the Cold Classical sub-population, the one group
of
TNOs with demonstrably distinct physical characteristics. Two
top-priority
Spitzer programs will soon observe and measure the sizes of
3
Cold Classical TNBs. This proposal seeks to determine the mutual
orbits
and thus masses of these systems, enabling computation of their
densities.
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).
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:
18845-0
- Null Genslew for Proposal 12077 - slot 14 @ 109/1252z
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSAcq 11
11
FGS
REAcq 7
7
OBAD
with Maneuver 7
7
SIGNIFICANT
EVENTS: (None)