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Daily Report # 4331



 
 
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Old April 2nd 07, 04:59 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report # 4331

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 Compton scattering {ICS} and 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)
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