Daily Report #4488

Notice: Due to the conversion of some ACS WFC or HRC observations into
WFPC2, or NICMOS observations after the loss of ACS CCD science
capability in January, there may be an occasional discrepancy between
a proposal's listed (and correct) instrument usage and the abstract
that follows it.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT***** # 4488

PERIOD COVERED: UT November , 2007 (DOY 317)

OBSERVATIONS SCHEDULED

ACS/SBC 11116

Exploring the Early FUV History of Cool Stars: Transition Regions at
30 Myr

Stellar magnetic activity derives from the so-called "dynamo," a
hydromagnetic interplay between overturning plasma motions and
differential rotation in stars cool enough to support significant
surface convection zones. The magnetic fields resulting from dynamo
action are in turn are responsible for a wide range of high-energy
emissions, including the spectacular outbursts called flares. Dynamo
powered magnetic activity is not confined solely to stars, but also
must occur, for example, in accretion disks of all descriptions, and
in some planets. A great deal is known about magnetic activity in
middle-aged G dwarfs like our Sun, thanks to its proximity. Less is
known, however, about the much younger stars, newly emerged from the
T-Tauri stage. Yet, it is during this phase that they reach the peak
of their magnetic activity, and subsidiary influences, such as the
impact of ionizing radiation and strong coronal winds on developing
solar systems, also are maximum. One of the key missing ingredients in
our current understanding are measurements of FUV emissions of such
stars, to complement the extensive collections of coronal {1-10 MK}
X-ray measurements, particularly from recent ROSAT, Chandra and
XMM-Newton surveys. We propose to conduct sensitive ACS/SBC prism
ultraviolet spectroscopy of selected fields in two young {30 Myr}
Galactic clusters--IC 2391 and IC 2602--to inventory the key C IV
emission index {~0.1 MK} over a much larger and more diverse sample of
coeval objects than has been possible hitherto. A key question is
whether the FUV emissions also suffer the "saturation" and
"super-saturation" at short rotation periods seen in coronal X-rays,
or whether they continue to rise in the fastest rotating stars. The
saturation behavior of the different temperature regimes holds
important clues to the organization of the surface active regions on
these very young stars, and should allow us to distinguish among
several competing models.

WFPC2 10583

Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects ?

We are requesting 32 HST orbits to help ascertain the nature of the
population that gives rise to the observed set of microlensing events
towards the LMC. The SuperMACHO project is an ongoing ground-based
survey on the CTIO 4m that has demonstrated the ability to detect LMC
microlensing events in real-time via frame subtraction. The
improvement in angular resolution and photometric accuracy available
from HST will allow us to 1} confirm that the detected flux excursions
arise from LMC source stars rather than extended objects {such as for
background supernovae or AGN}, and 2} obtain reliable baseline flux
measurements for the objects in their unlensed state. The latter
measurement is important to resolve degeneracies between the event
timescale and baseline flux, which will yield a tighter constraint on
the microlensing optical depth.

WFPC2 10766

A Deep X-ray Survey of the Small Magellanic Cloud

We request deep observations of 2 representative fields in the Small
Magellanic Cloud with Chandra and HST, with the primary goal of
measuring the luminosity function and space density of X-ray binaries
and other sources down to an unprecedented faint luminosity limit of
2x10E32 erg/s. This will be the faintest XLF ever obtained for any
galaxy, including our own. HST photometry to 24th magnitude in V and I
filters will identify the sources and provide Fx/Fopt, which will be
vital in quantifying the LMXB population and in measuring the
properties of the first coronally active stars ever detected in an
external galaxy.

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 DARKs. 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.

NIC2 10854

Coronagraphic Imaging of Bright New Spitzer Debris Disks II.

Fifteen percent of bright main sequence stars possess dusty
circumstellar debris disks revealed by far-infrared photometry. These
disks are signposts of planetary systems: collisions among larger,
unseen parent bodies maintain the observed dust population against
losses to radiation pressure and P-R drag. Images of debris disks at
optical, infrared, and millimeter wavelengths have shown central
holes, rings, radial gaps, warps, and azimuthal asymmetries which
indicate the presence of planetary mass perturbers. Such images
provide unique insights into the structure and dynamics of
exoplanetary systems. Relatively few debris disks have been spatially
resolved. Only thirteen have ever been resolved at any wavelength, and
at wavelengths 10 microns {where subarcsec resolution is available},
only ten. Imaging of many other debris disk targets has been attempted
with various HST cameras/coronagraphs and adaptive optics, but without
success. The key property which renders a debris disk observable in
scattered light is its dust optical depth. The ten disks imaged so far
all have a dust excess luminosity ~ 0.01% that of the central star;
no disks with smaller optical depths have been detected. Most main
sequence stars known to meet this requirement have already been
observed, so future progress in debris disk imaging depends on
discovering additional stars with large infrared excess. The Spitzer
Space Telescope offers the best opportunity in 20 years to identify
new examples of high optical depth debris disk systems. We propose to
complete ACS coronagraphic imaging followup of bright, new debris
disks discovered during the first two years of the Spitzer mission, by
observing three additional targets in Cycle 15. Our goal is to obtain
the first resolved images of these disks at ~3 AU resolution, define
the disk sizes and orientations,and uncover disk substructures
indicative of planetary perturbations. The results will open wider a
window into the structure of planetary systems.

NIC2 11157

NICMOS Imaging Survey of Dusty Debris Around Nearby Stars Across the
Stellar Mass Spectrum

Association of planetary systems with dusty debris disks is now quite
secure, and advances in our understanding of planet formation and
evolution can be achieved by the identification and characterization
of an ensemble of debris disks orbiting a range of central stars with
different masses and ages. Imaging debris disks in starlight scattered
by dust grains remains technically challenging so that only about a
dozen systems have thus far been imaged. A further advance in this
field needs an increased number of imaged debris disks. However, the
technical challege of such observations, even with the superb
combination of HST and NICMOS, requires the best targets. Recent HST
imaging investigations of debris disks were sample-limited not limited
by the technology used. We performed a search for debris disks from a
IRAS/Hipparcos cross correlation which involved an exhaustive
background contamination check to weed out false excess stars. Out of
~140 identified debris disks, we selected 22 best targets in terms of
dust optical depth and disk angular size. Our target sample represents
the best currently available target set in terms of both disk
brightness and resolvability. For example, our targets have higher
dust optical depth, in general, than newly identified Spitzer disks.
Also, our targets cover a wider range of central star ages and masses
than previous debris disk surveys. This will help us to investigate
planetary system formation and evolution across the stellar mass
spectrum. The technical feasibility of this program in two-gyro mode
guiding has been proven with on- orbit calibration and science
observations during HST cycles 13, 14, and 15.

WFPC2 11113

Binaries in the Kuiper Belt: Probes of Solar System Formation and
Evolution

The discovery of binaries in the Kuiper Belt and related small body
populations is powering a revolutionary step forward in the study of
this remote region. Three quarters of the known binaries in the Kuiper
Belt have been discovered with HST, most by our snapshot surveys. The
statistics derived from this work are beginning to yield surprising
and unexpected results. We have found a strong concentration of
binaries among low-inclination Classicals, a possible size cutoff to
binaries among the Centaurs, an apparent preference for nearly equal
mass binaries, and a strong increase in the number of binaries at
small separations. We propose to continue this successful program in
Cycle 16; we expect to discover at least 13 new binary systems,
targeted to subgroups where these discoveries can have the greatest
impact.

WFPC2 11202

The Structure of Early-type Galaxies: 0.1-100 Effective Radii

The structure, formation and evolution of early-type galaxies is still
largely an open problem in cosmology: how does the Universe evolve
from large linear scales dominated by dark matter to the highly
non-linear scales of galaxies, where baryons and dark matter both play
important, interacting, roles? To understand the complex physical
processes involved in their formation scenario, and why they have the
tight scaling relations that we observe today {e.g. the Fundamental
Plane}, it is critically important not only to understand their
stellar structure, but also their dark-matter distribution from the
smallest to the largest scales. Over the last three years the SLACS
collaboration has developed a toolbox to tackle these issues in a
unique and encompassing way by combining new non-parametric strong
lensing techniques, stellar dynamics, and most recently weak
gravitational lensing, with high-quality Hubble Space Telescope
imaging and VLT/Keck spectroscopic data of early-type lens systems.
This allows us to break degeneracies that are inherent to each of
these techniques separately and probe the mass structure of early-type
galaxies from 0.1 to 100 effective radii. The large dynamic range to
which lensing is sensitive allows us both to probe the clumpy
substructure of these galaxies, as well as their low-density outer
haloes. These methods have convincingly been demonstrated, by our
team, using smaller pilot-samples of SLACS lens systems with HST data.
In this proposal, we request observing time with WFPC2 and NICMOS to
observe 53 strong lens systems from SLACS, to obtain complete
multi-color imaging for each system. This would bring the total number
of SLACS lens systems to 87 with completed HST imaging and effectively
doubles the known number of galaxy-scale strong lenses. The deep HST
images enable us to fully exploit our new techniques, beat down
low-number statistics, and probe the structure and evolution of
early-type galaxies, not only with a uniform data-set an order of
magnitude larger than what is available now, but also with a fully
coherent and self-consistent methodological approach!

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

11059 - GSAcq (1,2,2) requires multiple attempts to achieve CT-DV

OTA SE review of PTAS processing revealed that GSAcq (1,2,2) required
multiple attempts to achieve CT DV on FGS1. (This occurred on day 314
@19:42:53)

11060 - OBAD Failed Identification

Upon acquisition of signal at 17:48:31 two 486 ESB messages were
observed, 1806 ("T2G Open Loop Timeout"), and 1902 "OBAD Failed
Identification".

Dump of ESB messages reveals that these messages occurred at 16:37:38
and 16:38:22, during the first of the two OBADs at 16:35:33, second
OBAD at 16:43:28 was successful with RSS correction of 1632.73
arcseconds.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL***** FAILURE TIMES

FGS GSacq************** 09***************** 09
FGS REacq************** 04***************** 04
OBAD with Maneuver **** 26***************** 25***************
317/16:38z

SIGNIFICANT EVENTS: (None)