Notice: For the foreseeable future, the daily reports may
contain
apparent discrepancies between some proposal descriptions
and the listed
instrument usage. This is due to the conversion of
previously approved
ACS WFC or HRC observations into WFPC2, or NICMOS
observations
subsequent to the loss of ACS CCD science capability in
late January.
HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4331
PERIOD COVERED: UT March 30,31 April 1, 2007 (DOY
089,090,091)
OBSERVATIONS SCHEDULED
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA calibration - CR Persistence Part 6
A new proceedure proposed to alleviate the CR-persistence
problem of
NICMOS. Dark frames will be obtained immediately upon
exiting the SAA
contour 23, and everytime a NICMOS exposure is scheduled
within 50
minutes of coming out of the SAA. The darks will be
obtained in parallel
in all three NICMOS Cameras. The POST-SAA darks will be
non- standard
reference files available to users with a USEAFTER date/time
mark. The
keyword 'USEAFTER=date/time' will also be added to the
header of each
POST-SAA DARK frame. The keyword must be populated with
the time, in
addition to the date, because HST crosses the SAA ~8 times
per day so
each POST-SAA DARK will need to have the appropriate time
specified, for
users to identify the ones they need. Both the raw and
processed images
will be archived as POST-SAA DARKSs. Generally we expect
that all NICMOS
science/calibration observations started within 50 minutes
of leaving an
SAA will need such maps to remove the CR persistence from
the science i
mages. Each observation will need its own CRMAP, as
different SAA
passages leave different imprints on the NICMOS detectors.
NIC3 11080
Exploring the Scaling Laws of Star Formation
As a variety of surveys of the local and distant Universe
are
approaching a full census of galaxy populations, our
attention needs to
turn towards understanding and quantifying the physical
mechanisms that
trigger and regulate the large-scale star formation rates
{SFRs} in
galaxies.
NIC1 11063
NICMOS Focus Monitoring
This program is a version of the standard focus sweep used
since cycle
7. It has been modified to go deeper and uses more narrow
filters for
improved focus determination. For Cycle14 a new source has
been added in
order to accomodate 2-gyro mode: the open cluster NGC1850.
The old
target, the open cluster NGC3603, will be used whenever
available and
the new target used to fill the periods when NGC3603 is
not visible.
Steps: a} Use refined target field positions as determined
from cycle 7
calibrations b} Use MULTIACCUM sequences of sufficient
dynamic range to
account for defocus c} Do a 17- point focus sweep, +/- 8mm
about the PAM
mechanical zeropoint for each cameras 1 and 2, in 1.0mm
steps. d} Use
PAM X/Y tilt and OTA offset slew compensations refined
from previous
focus monitoring/optical alignment activities
WFPC2 11030
WFPC2 WF4 Temperature Reduction #3
In the fall of 2005, a serious anomaly was found in images
from the WF4
CCD in WFPC2. The WF4 CCD bias level appeared to have
become unstable,
resulting in sporadic images with either low or zero bias
level. The
severity and frequency of the problem was rapidly
increasing, making it
possible that WF4 would soon become unusable if no
work-around were
found. Examination of bias levels during periods with
frequent WFPC2
images showed low and zero bias episodes every 4 to 6
hours. This
periodicity is driven by cycling of the WFPC2 Replacement
Heater, with
the bias anomalies occurring at the temperature peaks. The
other three
CCDs {PC1, WF2, and WF3} appear to be unaffected and
continue to operate
properly. Lowering the Replacement Heater temperature set
points by a
few degrees C effectively eliminates the WF4 anomaly. On 9
January 2006,
the upper set point of the WFPC2 Replacement Heater was
reduced from
14.9C to 12.2C. On 20 February 2006, the upper set point
was reduced
from 12.2C to 11.3C, and the lower set point was reduced
from 10.9C to
10.0C. These changes restored the WF4 CCD bias level;
however, the bias
level has begun to trend downwards again, mimicking its
behavior in late
2004 and early 2005. A third temperature reduction is
planned for March
2007. We will reduce the upper set point of the heater
from 11.3C to
10.4C and the lower set point from 10.0C to 9.1C. The
observations
described in this proposal will test the performance of
WFPC2 before and
after this temperature reduction. Additional temperature
reductions may
be needed in the future, depending on the performance of
WF4. Orbits:
internal 26, external 1
WFPC2 11029
WFPC2 CYCLE 15 Intflat Linearity Check and Filter Rotation
Anomaly
Monitor
Intflat observations will be taken to provide a linearity
check: the
linearity test consists of a series of intflats in F555W,
in each gain
and each shutter. A combination of intflats, visflats, and
earthflats
will be used to check the repeatability of filter wheel
motions.
{Intflat sequences tied to decons, visits 1-18 in prop
10363, have been
moved to the cycle 15 decon proposal xxxx for easier
scheduling.} Note:
long-exposure WFPC2 intflats must be scheduled during ACS
anneals to
prevent stray light from the WFPC2 lamps from
contaminating long ACS
external exposures.
WFPC2 11024
WFPC2 CYCLE 15 INTERNAL MONITOR
This calibration proposal is the Cycle 15 routine internal
monitor for
WFPC2, to be run weekly to monitor the health of the
cameras. A variety
of internal exposures are obtained in order to provide a
monitor of the
integrity of the CCD camera electronics in both bays {both
gain 7 and
gain 15 -- to test stability of gains and bias levels}, a
test for
quantum efficiency in the CCDs, and a monitor for possible
buildup of
contaminants on the CCD windows. These also provide raw
data for
generating annual super-bias reference files for the
calibration
pipeline.
WFPC2 11023
WFPC2 CYCLE 15 Standard Darks - part 1
This dark calibration program obtains dark frames every
week in order to
provide data for the ongoing calibration of the CCD dark
current rate,
and to monitor and characterize the evolution of hot
pixels. Over an
extended period these data will also provide a monitor of
radiation
damage to the CCDs.
FGS 10989
Astrometric Masses of Extrasolar Planets and Brown Dwarfs
We propose observations with HST/FGS to estimate the
astrometric
elements {perturbation orbit semi-major axis and
inclination} of
extra-solar planets orbiting six stars. These companions
were originally
detected by radial velocity techniques. We have
demonstrated that FGS
astrometry of even a short segment of reflex motion, when
combined with
extensive radial velocity information, can yield useful
inclination
information {McArthur et al. 2004}, allowing us to
determine companion
masses. Extrasolar planet masses assist in two ongoing
research
frontiers. First, they provide useful boundary conditions
for models of
planetary formation and evolution of planetary systems.
Second, knowing
that a star in fact has a plantary mass companion,
increases the value
of that system to future extrasolar planet observation
missions such as
SIM PlanetQuest, TPF, and GAIA.
WFPC2 10877
A Snapshot Survey of the Sites of Recent, Nearby
Supernovae
During the past few years, robotic {or nearly robotic}
searches for
supernovae {SNe}, most notably our Lick Observatory
Supernova Search
{LOSS}, have found hundreds of SNe, many of them in quite
nearby
galaxies {cz < 4000 km/s}. Most of the objects were
discovered before
maximum brightness, and have follow-up photometry and
spectroscopy; they
include some of the best-studied SNe to date. We propose
to conduct a
snapshot imaging survey of the sites of some of these
nearby objects, to
obtain late-time photometry that {through the shape of the
light and
color curves} will help reveal the origin of their
lingering energy. The
images will also provide high-resolution information on
the local
environments of SNe that are far superior to what we can
procure from
the ground. For example, we will obtain color-color and
color-magnitude
diagrams of stars in these SN sites, to determine the SN
progenitor
masses and constraints on the reddening. Recovery of the
SNe in the new
HST images will also allow us to actually pinpoint their
progenitor
stars in cases where pre- explosion images exist in the
HST archive.
This proposal is an extension of our successful Cycle 13
snapshot survey
with ACS. It is complementary to our Cycle 15 archival
proposal, which
is a continuation of our long-standing program to use existing
HST
images to glean information about SN environments.
NIC1 10859
Precise Measurements of Sgr A* Flare Activity
Correlated X-ray and near-IR flare emission from Sgr A*,
the closest
supermassive black hole, contains information about the
hydrodynamics,
energetics, and accretion behavior of matter within the
innermost ten
Schwarzschild radii of the hole. We propose HST/NICMOS
observations of
near-IR flares, in conjunction with already approved
obsrevations using
XMM-Newton {214 ksec} and CSO {3 nights}, which can make
the precise,
new measurements necessary to understand the radiation
mechanism and low
luminosity of Sgr A*. HST/NICMOS is required due to its
very low and
stable background, and its stable, tightly focused PSF,
which allow
accurate measurement of fainter flares than can be
observed using
groundbased adaptive optics systems. We will measure the
spectral index
distribution, the time-averaged flux and duration of
flares, and the
statistics of flare activity, and will confirm previously
reported
quasi-periodic variability. These measurements will have
far-reaching
implications for testing the inverse
synchrotron models of low-luminosity flares, for
understanding the
process of accretion onto and outflow from supermassive
black holes, and
for constraining the acceleration mechanism of flares and
the inferred
black hole spin. This knowledge, in turn, will help us
understand more
generally low-luminosity AGN and X-ray binaries in a very low/quiescent
accretion state.
NIC1 10858
NICMOS Imaging of the z ~ 2 Spitzer Spectroscopic Sample
of
Ultraluminous Infrared
We propose to obtain NICMOS images of the first large
sample of high-z
ultra-luminous infrared galaxies {ULIRGs} whose redshifts
and physical
states have been determined with Spitzer mid-IR spectra.
The detection
of strong silicate absorption and/or PAH emission lines
suggest that the
these sources are a mixture of highly obscured starbursts,
AGNs and
composite systems at z=2. Although some of the spectra
show PAH emission
similar to local starburst ULIRGs, their bolometric
luminosities are
roughly an order of magnitude higher. One important
question is if major
mergers, which are the trigger for 95% of local ULIRGs,
also drive this
enormous energy output observed in our z=2 sample. The
NICMOS images
will allow us to {1} measure surface brightness profiles
of z~2 ULIRGs
and establish if major mergers could be common among our
luminous
sources at these early epochs, {2} determine if starbursts
and AGNs
classified based on their mid-IR spetra would have
different
morphological signatures, thus different dynamic state;
{3} make
comparisons with the similar studies of ULIRGs at z ~ 0 -
1, thus infer
any evolutionary connections between high-z ULIRGs and the
formation of
normal, massive galaxies and quasars observed today.
WFPC2 10833
Host Galaxies of Reverberation Mapped AGNs
We propose to obtain unsaturated high-resolution images of
17
reverberation-mapped active galactic nuclei in order to
remove the
point-like nuclear light from each image, thus yielding a
"nucleus-free"
image of the host galaxy. This will allow investigation of
host galaxy
properties: our particular interest is determination of
the host-galaxy
starlight contribution to the reverberation-mapping
observations. This
is necessary {1} for accurate determination of the
relationship between
the AGN nuclear continuum flux and the size of the broad
Balmer-line
emitting regions of AGNs, which is important in estimating
black hole
masses for large samples of QSOs, and {2} for accurate
determination of
the bolometric luminosity of the AGN proper. Through
observations in
Cycles 12 and 14, we have obtained or will obtain images
of 18 of the 35
objects in the reverberation-mapping compilation of
Peterson et al.
{2004}. These observations revealed that the host-galaxy
contribution,
even in the higher-luminosity AGNs, is higher than
expected and that all
of the reverberation- mapped AGNs will have to be observed,
not just the
lower-luminosity sources; each source is different, and
each source is
important. Therefore we request time to observe the 17
remaining
reverberation-mapped AGNs.
WFPC2 10815
The Blue Hook Populations of Massive Globular Clusters
Blue hook stars are a class of hot {~35,000 K} subluminous
horizontal
branch stars that have been recently discovered using HST
ultraviolet
images of the globular clusters omega Cen and NGC 2808.
These stars
occupy a region of the HR diagram that is unexplained by
canonical
stellar evolution theory. Using new theoretical
evolutionary and
atmospheric models, we have shown that the blue hook stars
are very
likely the progeny of stars that undergo extensive
internal mixing
during a late helium core flash on the white dwarf cooling
curve. This
"flash mixing" produces an enormous enhancement
of the surface helium
and carbon abundances, which suppresses the flux in the
far ultraviolet.
Although flash mixing is more likely to occur in stars
that are born
with high helium abundances, a high helium abundance, by
itself, does
not explain the presence of a blue hook population - flash
mixing of the
envelope is required. We propose ACS ultraviolet
{SBC/F150LP }
observations of the five additional globular clusters for
which the presence of blue hook stars is suspected from
longer
wavelength observations. Like omega Cen and NGC 2808,
these five targets
are also among the most massive globular clusters, because
less massive
clusters show no evidence for blue hook stars. Because our
targets span
1.5 dex in metallicity, we will be able to test our
prediction that
flash-mixing should be less drastic in metal-rich blue
hook stars. In
addition, our observations will test the hypothesis that
blue hook stars
only form in globular clusters massive enough to retain
the helium-
enriched ejecta from the first stellar generation. If this
hypothesis is
correct, then our observations will yield important
constraints on the
chemical evolution and early formation history in globular
clusters, as
well as the role of helium self-enrichment in producing
blue horizontal
branch morphologies and multiple main sequence turnoffs.
Finally, our
observations will provide new insight into the formation
of the hottest
horizontal branch stars, with implications for the origin
of the hot
helium-rich subdwarfs in the Galactic field.
ACS/SBC 10810
The Gas Dissipation Timescale: Constraining Models of
Planet Formation
We propose to constrain planet-formation models by
searching for
molecular hydrogen emission around young {10-50 Myr}
solar-type stars
that have evidence for evolved dust disks. Planet
formation models show
that the presence of gas in disks is crucial to the
formation of BOTH
giant and terrestrial planets, influences dust dynamics,
and through
tidal interactions with giant planets leads to orbital
migration.
However, there is a lack of systematic information on the
presence and
lifetime of gas residing at planet-forming radii. We will
use a newly
identified broad continuum emission feature of molecular
hydrogen at
1600 Angstrom to search for residual gas within an orbital
radius of
5-10 AU around young stars that have evolved beyond the
optically thick
T Tauri phase. These observations will enable the most sensitive
probe
to date of remant gas in circumstellar disks, detecting
surfaces
densites of ~0.0001 g/cm^2, or less than 10^-5 of the
theoretical
"mininum mass" solar nebula from which our solar
system is thought to
have formed. Our observations are designed to be
synergistic with
ongoing searches for gas emission that is being performed
using the
Spitzer Space Telescope in that the proposed HST
observations are ~100
times more sensitive and will have 50 times higher angular
resolution.
These combined studies will provide the most comprehensive
view of
residual gas in proto-planetary disks and can set
important constraints
on models of planet formation.
WFPC2 10798
Dark Halos and Substructure from Arcs & Einstein Rings
The surface brightness distribution of extended
gravitationally lensed
arcs and Einstein rings contains super-resolved
information about the
lensed object, and, more excitingly, about the smooth and
clumpy mass
distribution of the lens galaxies. The source and lens
information can
non-parametrically be separated, resulting in a direct
"gravitational
image" of the inner mass-distribution of
cosmologically-distant galaxies
{Koopmans 2005; Koopmans et al. 2006 [astro-ph/0601628]}.
With this goal
in mind, we propose deep HST ACS-F555W/F814W and
NICMOS-F160W WFC
imaging of 20 new gravitational-lens systems with
spatially resolved
lensed sources, of the 35 new lens systems discovered by
the Sloan Lens
ACS Survey {Bolton et al. 2005} so far, 15 of which are
being imaged in
Cycle-14. Each system has been selected from the SDSS and
confirmed in
two time- efficient HST-ACS snapshot programs {cycle
13&14}.
High-fidelity multi-color HST images are required {not
delivered by the
420s snapshots} to isolate these lensed images {properly cleaned,
dithered and extinction-corrected} from the lens galaxy
surface
brightness distribution, and apply our "gravitational
maging" technique.
Our sample of 35 early-type lens galaxies to date is by
far the largest,
still growing, and most uniformly selected. This minimizes
selection
biases and small-number statistics, compared to smaller,
often
serendipitously discovered, samples. Moreover, using the
WFC provides
information on the field around the lens, higher S/N and a
better
understood PSF, compared with the HRC, and one retains
high spatial
resolution through drizzling. The sample of galaxy mass
distributions -
determined through this method from the arcs and Einstein
ring HST
images - will be studied to: {i} measure the smooth mass
distribution of
the lens galaxies {dark and luminous mass are separated
using the HST
images and the stellar M/L values derived from a joint
stellar-dynamical
analysis of each system}; {ii} quantify statistically and
individually
the incidence of mass-substructure {with or without
obvious luminous
counter- parts such as dwarf galaxies}. Since dark-matter
substructure
could be more prevalent at higher redshift, both results
provide a
direct test of this prediction of the CDM hierarchical
structure-formation model.
WFPC2 10786
Rotational state and composition of Pluto's outer
satellites
We propose an intricate set of observations aimed at
discovering the
rotational state of the newly discovered satellites of
Pluto, S/2005 P1
and S/2005 P2. These observations will indicate if the
satellites are in
synchronous rotation or not. If they are not, then the
observations will
determine the rotational period or provide tight
constraints on the
amplitude. The other primary goal is to extend the
wavelength coverage
of the colors of the surface and allow us to constrain the
surface
compositions of both objects. From these data we will also
be able to
significantly improve the orbits of P1 and P2, improve the
measurement
of the bulk density of Charon, and search for albedo changes
on the
surface of Pluto.
FGS 10612
Binary Stars in Cyg OB2: Relics of Massive Star Formation
in a
Super-Star Cluster
We propose to make a high angular resolution SNAP survey
of the massive
stars in the nearby, super-star cluster Cyg OB2. We will use
FGS1r TRANS
mode observations to search for astrometric companions in
the separation
range of 0.01 to 1.00 arcsec and in the magnitude
difference range
smaller than 4 magnitudes. The observations will test the
idea that the
formation of very massive stars involves mergers and the
presence of
nearby companions. Discovery of companions to massive
stars in this
relatively nearby complex will provide guidance in the
interpretation of
apparently supermassive stars in distant locations. The
search for
companions will also be important for verification of
fundamental
parameters derived from spectroscopy, adjustments to main
sequence
fitting and distance estimations, determining third light
contributions
of eclipsing binaries, identifying wide colliding wind
binaries,
studying the relationship between orbital and spin angular
momentum, and
discovering binaries amenable to future mass
determinations. The massive
star environment in Cyg OB2 may be similar to the kinds
found in the
earliest epoch of star formation, so that a study of the
role of
binaries in Cyg OB2 will help us understand the formation
processes of
the first stars in the Universe.
NIC2 10603
Multiwavelength Imaging of Edge-on Protoplanetary Disks:
Quantifying the
Growth of Circumstellar Dust
Young, edge-on circumstellar disks are uniquely valuable
laboratories
for the study of planet formation. In these objects, the
central star is
occulted from direct view, significant PSF artifacts are
absent, and the
disk is clearly seen as a central dust lane flanked by
faint disk
reflected light. The detailed morphology of these nebulae
and its
variation with wavelength provide crucial information on
the disk
internal structure and the properties of its constituent
dust grains. A
key observable is the slope defining the wavelength
dependence of the
dust scattering opacity, which becomes shallower when
grain growth has
taken place; multiwavelength resolved disk images are the
key dataset
enabling such measurements. Recent analyses of three
different edge-on
disks have revealed a diversity in their dust properties
that is
indicative of different degrees of dust grain evolution
having taken
place in each system. This characterization of disk grain
growth, when
applied comparatively to a larger sample of these objects,
would enable
the construction of an evolutionary sequence of young
disks at
successive stages on the road to planet formation. In
pursuit of this
goal, we have identified a sample of 15 edge-on disks
previously
discovered by HST or groundbased telescopes, but for which
high
fidelity, high spatial resolution images do not yet exist
in both the
optical and near-infrared. We propose broad- band
multicolor imaging
with NICMOS of all these targets, and ACS imaging of nine
of these
targets In combination with existing data, the proposed
images will form
a complete database of high resolution optical/near-IR
images for these
15 disk systems. Scattered light modeling will be used to
derive the
disk structure and dust properties, yielding results that
will be of
fundamental importance for our understanding of grain
properties during
protoplanetary disk evolution.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
10762 - GSacq(1,2,2) failed to RGA control.
The GSacq(1,2,2) scheduled at 09/19:22:32 failed during LOS. At AOS
19:44:09 flags were present indication the GSacq failed due to receiving
stop flag QF1STOPF on FGS 1. The Map at 19:29:58 showed errors of
V1=-0.27, V2=-2.13, V3=-4.25, and RSS= 4.76
10763 - GSAcq(2,3,3) results in fine lock backup (2,0,2)
using FGS2.
Upon acquisition of signal at 091/04:09:45, the GSAcq(2,3,3) scheduled
at
091/03:43:55 - 03:52:00 had resulted to fine lock backup (2,0,2)
using FGS2 due to (QF3STOPF) stop flag indication on FGS3.
Pre-acquisition OBADs (RSS) attitude correction values not available due
to
LOS. Post-acquisition OBAD/MAP not scheduled.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
28
27
FGS
REacq
10
10
OBAD with Maneuver
77
77
SIGNIFICANT EVENTS: (None)