Daily Report #4562

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4562

PERIOD COVERED: UT March 06, 2008 (DOY 066)

OBSERVATIONS SCHEDULED

ACS/SBC 11050

ACS UV contamination monitor

The observations consist of imaging and spectroscopy with SBC of the cluster
NGC 6681 in order to monitor the temporal evolution of the UV sensitivity of
the SBC.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

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 i mages. Each observation will need its own CRMAP, as
different SAA passages leave different imprints on the NICMOS detectors.

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 challenge 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.

WEPC2 11196

An Ultraviolet Survey of Luminous Infrared Galaxies in the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared
selected galaxies exceeds that of optically selected galaxies. These
Luminous Infrared Galaxies {LIRGs} are primarily interacting or merging disk
galaxies undergoing starbursts and creating/fueling central AGN. We propose
far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W} UV imaging of a sample of 27
galaxies drawn from the complete IRAS Revised Bright Galaxy Sample {RBGS}
LIRGs sample and known, from our Cycle 14 B and I-band ACS imaging
observations, to have significant numbers of bright {23 B 21 mag} star
clusters in the central 30 arcsec. The HST UV data will be combined with
previously obtained HST, Spitzer, and GALEX images to {i} calculate the ages
of the clusters as function of merger stage, {ii} measure the amount of UV
light in massive star clusters relative to diffuse regions of star
formation, {iii} assess the feasibility of using the UV slope to predict the
far-IR luminosity {and thus the star formation rate} both among and within
IR-luminous galaxies, and {iv} provide a much needed catalog of rest- frame
UV morphologies for comparison with rest-frame UV images of high-z LIRGs and
Lyman Break Galaxies. These observations will achieve the resolution
required to perform both detailed photometry of compact structures and
spatial correlations between UV and redder wavelengths for a physical
interpretation our IRX-Beta results. The HST UV data, combined with the HST
ACS, Spitzer, Chandra, and GALEX observations of this sample, will result in
the most comprehensive study of luminous starburst galaxies to date.

WFPC2 11103

A Snapshot Survey of The Most Massive Clusters of Galaxies

We propose the continuation of our highly successful SNAPshot survey of a
sample of 125 very X-ray luminous clusters in the redshift range 0.3-0.7. As
demonstrated by the 25 snapshots obtained so far in Cycle14 and Cycle15
these systems frequently exhibit strong gravitational lensing as well as
spectacular examples of violent galaxy interactions. The proposed
observations will provide important constraints on the cluster mass
distributions, the physical nature of galaxy-galaxy and galaxy-gas
interactions in cluster cores, and a set of optically bright, lensed
galaxies for further 8-10m spectroscopy. All of our primary science goals
require only the detection and characterization of high-surface-brightness
features and are thus achievable even at the reduced sensitivity of WFPC2.
Because of their high redshift and thus compact angular scale our target
clusters are less adversely affected by the smaller field of view of WFPC2
than more nearby systems. Acknowledging the broad community interest in this
sample we waive our data rights for these observations. Due to a clerical
error at STScI our approved Cycle15 SNAP program was barred from execution
for 3 months and only 6 observations have been performed to date -
reinstating this SNAP at Cycle16 priority is of paramount importance to
reach meaningful statistics.

WFPC2 11138

The Physics of the Jets of Powerful Radio Galaxies and Quasars

We propose to obtain HST polarimetry of the jets of the quasars 1150+497 and
PKS 1136-135. Our goal is to solve the riddle of their high-energy emission
mechanism, and tackle issues such as particle acceleration and jet dynamics.
Our targets are the optically brightest quasar jets, and they span the range
of luminosities and beaming parameters seen in these objects. Recent
observations with Spitzer, HST and Chandra have shed new light on the
spectral morphology of quasar jets, throwing wide open the question of the
nature of their optical and X-ray emission. Three mechanisms are possible,
including synchrotron emission as well as two Comptonization processes.
Polarimetry can uniquely determine which of these mechanisms operates in the
optical. We will compare the optical polarimetry to in- hand radio
polarimetry as well as in-hand and new Spitzer, HST and Chandra imaging to
gain new insights on the structure of these jets, as well as particle
acceleration mechanisms and jet dynamics.

WFPC2 11233

Multiple Generations of Stars in Massive Galactic Globular Clusters

This is a follow-up to recent HST imaging of NGC 2808, which discovered that
its main sequence is triple, with three well-separated parallel branches
{Fig.~1}. Along with the double MS of Omega Centauri, this challenges the
long-held paradigm that globular clusters are simple, single stellar
populations. The cause of this main sequence multiplicity in both clusters
is likely to be differences in helium abundance, which could play a
fundamental role in the understanding of stellar populations. We propose to
image seven more of the most massive globular clusters, to examine their
main sequences for indications of splitting.

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: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 08 08
FGS REacq 06 06
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)