Daily Report # 4353

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 # 4353

PERIOD COVERED: UT May 01, 2007 (DOY 121)

OBSERVATIONS SCHEDULED

WFPC2 10468

Jupiter's Upper Stratospheric Hazes Probed with Ganymede

I propose to observe a disappearance of Ganymede behind the dark limb of
Jupiter with five filters of the ACS/HRC camera. Two exposures in each
filter can be taken during such an event. The images will provide the
spectral variation of the altitude of the apparent limb of Jupiter. The
altitude of the apparent limb is dependent on the presence of hazes in
Jupiter's stratosphere. Hazes of vertical optical depths below 0.001 could
be detected with these observations, providing an extremely sensitive probe
of high hazes. The observations probe altitudes levels near the 1-mb
pressure level, for which we have very limited data. The creation of
aerosols, their growth, and their transport by winds is currently a mostly
theoretical study. It would significantly benefit from constraints derived
from the proposed observations. ACS/HRC is the only instrument capable of
the required spatial resolution in the ultraviolet. Furthermore, a favorable
geometry of Ganymede's orbit occurs only once every six years. This proposal
achieves unique results with a minimum of HST time.

WFPC2 10832

Solving the microlensing puzzle: An HST high-resolution imaging approach

We propose to use the HST Advanced Camera for Surveys High Resolution
Channel to obtain high resolution imaging data for 10 bona-fide LMC
microlensing events seen in the original MACHO survey. The purpose of this
survey will be to assess whether or not the lens and source stars have
separated enough to be resolved since the original microlensing event took
place - about a decade has passed since the original MACHO survey and the
HST WFPC2 follow-up observations of the microlensing events. If the
components of the lensing event are resolved, we will determine the apparent
magnitude and color of both the lens and the source stars. These data, in
combination with Spitzer/IRAC data and Magellan near-IR JHK data, will be
used to ascertain the basic properties of the lens stars. With the majority
of the microlensing events in the original MACHO survey observed at the
highest spatial resolution currently possible, we will be able to draw
important conclusions as to what fraction of these events have lenses which
belong to some population of dwarf stars in the disk and what fraction must
be due to lenses in the halo or beyond. These data will greatly increase our
understanding of the structure of the Galaxy by characterizing the stellar
population responsible for the gravitational microlensing.

WFPC2 10896

An Efficient ACS Coronagraphic Survey for Debris Disks around Nearby Stars

We propose to finish our Cycle 11 optical survey for nearby debris disks
using the ACS/HRC coronagraph. Out of 43 orbits originally proposed for the
survey, 23 orbits were allocated, leading to a survey of 22 stars, from
which two new debris disks were imaged for the first time. Our analysis of
the initial survey gives an empirical estimate for the detection rate of
debris disks relative to heliocentric distance and dust optical depth. Our
target list for Cycle 15 is now optimized to yield more frequent disk
detections. Likewise our observing strategy is improved to maximize
sensitivity per telescope orbit allocated. Therefore we present the most
efficient survey possible. The scientific motivation is to obtain scattered
light images of previously unresolved debris disks to determine their
viewing geometry and physical architecture, both of which may characterize
the underlying planetary system. We choose 25 debris disk targets for which
we predict a detection rate of 25% ? 5%. Four targets have extrasolar
planets from which the viewing geometry revealed by a disk detection will
resolve the v sin{i} ambiguity in the planet masses. These targets present
the remarkable opportunity of finally seeing a debris disk in system with
known planets.

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

A new procedure proposed to alleviate the CR-persistence problem of NICMOS.
Dark frames will be obtained immediately upon exiting the SAA contour 23,
and every time 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 images. Each observation will need its own CRMAP, as
different SAA passages leave different imprints on the NICMOS detectors.

NIC3 10792

Quasars at Redshift z=6 and Early Star Formation History

We propose to observe four high-redshift quasars {z=6} in the NIR in order
to estimate relative Fe/Mg abundances and the central black hole mass. The
results of this study will critically constrain models of joint quasar and
galaxy formation, early star formation, and the growth of supermassive black
holes. Different time scales and yields for alpha-elements {like O or Mg}
and for iron result into an iron enrichment delay of ~0.3 to 0.6 Gyr. Hence,
despite the well-known complexity of the FeII emission line spectrum, the
ratio iron/alpha - element is a potentially useful cosmological clock. The
central black hole mass will be estimated based on a recently revised back
hole mass - luminosity relationship. The time delay of the iron enrichment
and the time required to form a supermassive black hole {logM8 Msol, tau
~0.5Gyr} as evidenced by quasar activity will be used to date the beginning
of the first intense star formation, marking the formation of the first
massive galaxies that host luminous quasars, and to constrain the epoch when
supermassive black holes start to grow by accretion.

WFPC2 10845

HUNTING FOR OPTICAL COMPANIONS TO BINARY MILLISECOND PULSARS IN TERZAN 5 AND
NGC6266

We propose deep WFPC2 and NICMOS observations to search for optical
companions to binary millisecond pulsar {MSPs} in two Globular Clusters
{GCs}: Terzan 5 and NGC6266. Terzan 5 has the largest MSP population of any
GC: 33 MSP {17 in binary systems} have been discovered up to now in this
stellar system. NGC6266 ranks fifth among the GC for wealth of MSPs but it
is the only one in which all the {six} detected MSPs are in binary systems.
Only 5 optical counterparts to binary MSP companions are known in GCs {two
of them have been discovered by our group}: hence even the addition of a few
new identifications are crucial to investigate the variety of processes
occurring in binary MSPs in dense environment. The observations proposed
here would easily double/triple the existing sample of known MSP companions,
allowing the first meaningful study of the phenomena which drive the
formation and evolution of these exotic systems. Moreover, since most of
binary MSP in GC are formed via stellar interactions in the high density
regions of the cluster, the determination of the nature of the companion and
the incidence of this collisionally induced population have a significant
impact on our knowledge of the cluster dynamics. Even more interesting, the
study of the optical companions to NSs in a GC allows to derive tighter
constraints {than those obtainable for NS binaries in the galactic field} on
the properties {mass, orbital inclination and so on} of the compation star.
This has, in turn, an intrisic importance for fundamental physics since it
offers the opportunity of measuring the mass of the NS and hence to put
constraints to the equation of state of matter at nuclear equilibrium
density.

WFPC2 10890

Morphologies of the Most Extreme High-Redshift Mid-IR-Luminous Galaxies

The formative phase of the most massive galaxies may be extremely luminous,
characterized by intense star- and AGN-formation. Till now, few such
galaxies have been unambiguously identified at high redshift, restricting us
to the study of low-redshift ultraluminous infrared galaxies as possible
analogs. We have recently discovered a sample of objects which may indeed
represent this early phase in galaxy formation, and are undertaking an
extensive multiwavelength study of this population. These objects are bright
at mid-IR wavelengths {F[24um]0.8mJy}, but deep ground based imaging
suggests extremely faint {and in some cases extended} optical counterparts
{R~24-27}. Deep K-band images show barely resolved galaxies. Mid-infrared
spectroscopy with Spitzer/IRS reveals that they have redshifts z ~ 2-2.5,
suggesting bolometric luminosities ~10^{13-14}Lsun! We propose to obtain
deep ACS F814W and NIC2 F160W images of these sources and their environs in
order to determine kpc-scale morphologies and surface photometry for these
galaxies. The proposed observations will help us determine whether these
extreme objects are merging systems, massive obscured starbursts {with
obscuration on kpc scales!} or very reddened {locally obscured} AGN hosted
by intrinsically low-luminosity galaxies.

WFPC2 11027

Visible Earth Flats

This proposal monitors flatfield stability. This proposal obtains sequences
of Earth streak flats to construct high quality flat fields for the WFPC2
filter set. These flat fields will allow mapping of the OTA illumination
pattern and will be used in conjuction with previous internal and external
flats to generate new pipeline superflats. These Earth flats will complement
the Earth flat data obtained during cycles 4-14.

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.

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:

18054-0 - Preview KF Sun Vector Data via Telemetry Diags
18060-0 - MSS/Gyro1 KF Initialization Convergence Testing for SMS 120
18061-0 - MSS KF Adding Gyro1 Convergence Testing for SMS 120
18064-0 - PCS KF OOT Support, 121/18:20z
18065-0 - PCS KF OOT Support, 121/19:49z

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 13 13
FGS REacq 02 02
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS:

Evaluation of Universal Kalman Filter performance continued. Multiple text
segments were executed, all of them successfully. Details follow.

Background Kalman Filter Operations Day 121:

The Kalman Filter (KF) was restarted on 120/14:35:30 after being halted on
116/21:00 for the Clock Roll-over.

The KF was halted at 121/11:22 (OR 18062-0) during orbit day and during a
T2G guiding interval. The filter was restarted at 121/11:25 during orbit
day and during a fast changing B-field while inertially fixed. The filter
was activated with only the MSS enabled. All UKF parameters showed nominal
operation. The test was an MSS Initialization Test Case with the vehicle
inertially fixed during a fast changing B-field (M_0_INF, Test #3). The
MSS/CSS default KF configuration was restored at 121/12:13.

The Gyro1 sensor input was added to the KF at 121/15:10 (OR 18059-1) during
orbit day with no vehicle slew and during a T2G guiding interval. The
filter was running with the MSS and CSS sensor inputs enabled and converged.
All UKF parameters showed nominal operation. The test was an MSS/CSS/Gyro1
test case with the Gyro1 sensor input removed at 121/16:30 with the filter
running. The Gyro1 input was removed during an M2G guiding interval, during
orbit day, during a vehicle maneuver and during a slow changing B-field
(MC_G1_HVS, Test #32). The response to the removal of the gyro input was
nominal and the filter remained converged. The removal of the gyro input
restored the default MSS/CSS configuration of the filter.

The KF was halted at 121/18:10 (OR 18060-0) during orbit day and during an
M2G guiding interval. The filter was restarted at 121/18:21 during orbit
day and during a slow changing B-field. The filter was activated with the
MSS and Gyro1 sensor inputs enabled. All UKF parameters showed nominal
operation. The test was an MSS/Gyro1 Initialization test case during a
vehicle slew, during a slow changing B-field (M_G1_IVS, Test #12). The
Gyro1 sensor input was removed at 121/18:34, however the CSS sensor input
was intentionally left disabled to minimize the configuration changes needed
for the next test at 19:57 and because the originally scheduled TDRSS
service to execute the reconfiguration was deleted.

The Gyro1 sensor input was added to the KF at 121/19:57 (OR 18061-0) during
orbit day, during a vehicle slew, during an M2G guiding interval and during
a slow changing B-field. The filter was running with only the MSS sensor
input enabled and converged. All UKF parameters showed nominal operation
after the addition of the gyro sensor input enabling. The test was an
MSS/Gyro1 test case with the Gyro1 sensor input added with the filter
enabled and converged (M_G1_RVS, Test #20). The CSS sensor input was
re-enabled, the Gyro1 sensor input removed and the filter restarted during a
T2G guiding interval and during orbit night at 121/20:15. This
reconfiguration restored the default MSS/CSS configuration of the filter.