Daily Report #4395

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 # 4395

PERIOD COVERED: UT June 29,30, July 01, 2007 (DOY 180,181,182)

OBSERVATIONS SCHEDULED

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.

WFPC2 11289

SL2S: The Strong Lensing Legacy Survey

Recent systematic surveys of strong galaxy-galaxy lenses {CLASS, SLACS,
GOODS, etc.} are producing spectacular results for galaxy masses roughly
below a transition mass M~10^13 Mo. The observed lens properties and their
evolution up to z~0.2, consistent with numerical simulations, can be
described by isothermal elliptical potentials. In contrast, modeling of
giant arcs in X-ray luminous clusters {halo masses M ~10^13 Mo} favors NFW
mass profiles, suggesting that dark matter halos are not significantly
affected by baryon cooling. Until recently, lensing surveys were neither
deep nor extended enough to probe the intermediate mass density regime,
which is fundamental for understanding the assembly of structures. The CFHT
Legacy Survey now covers 125 square degrees, and thus offers a large
reservoir of strong lenses probing a large range of mass densities up to
z~1. We have extracted a list of 150 strong lenses using the most recent
CFHTLS data release via automated procedures. Following our first SNAPSHOT
proposal in cycle 15, we propose to continue the Hubble follow-up targeting
a larger list of 130 lensing candidates. These are intermediate mass range
candidates {between galaxies and clusters} that are selected in the redshift
range of 0.2-1 with no a priori X-ray selection. The HST resolution is
necessary for confirming the lensing candidates, accurate modeling of the
lenses, and probing the total mass concentration in galaxy groups up to z~1
with the largest unbiased sample available to date.

WFPC2 11235

HST NICMOS Survey of the Nuclear Regions 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 of merging
disk galaxies undergoing enhanced star formation and Active Galactic Nuclei
{AGN} activity, possibly triggered as the objects transform into massive S0
and elliptical merger remnants. We propose NICMOS NIC2 imaging of the
nuclear regions of a complete sample of 88 L_IR 10^11.4 L_sun luminous
infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS: i.e., 60
micron flux density 5.24 Jy}. This sample is ideal not only in its
completeness and sample size, but also in the proximity and brightness of
the galaxies. The superb sensitivity and resolution of NICMOS NIC2 on HST
enables a unique opportunity to study the detailed structure of the nuclear
regions, where dust obscuration may mask star clusters, AGN and additional
nuclei from optical view, with a resolution significantly higher than
possible with Spitzer IRAC. This survey thus provides a crucial component to
our study of the dynamics and evolution of IR galaxies presently underway
with Wide-Field, HST ACS/WFC and Spitzer IRAC observations of these 88
galaxies. Imaging will be done with the F160W filter {H-band} to examine as
a function of both luminosity and merger stage {i} the luminosity and
distribution of embedded star clusters, {ii} the presence of optically
obscured AGN and nuclei, {iii} the correlation between the distribution of
1.6 micron emission and the mid-IR emission as detected by Spitzer IRAC,
{iv} the evidence of bars or bridges that may funnel fuel into the nuclear
region, and {v} the ages of star clusters for which photometry is available
via ACS/WFC observations. The NICMOS data, combined with the HST ACS,
Spitzer, and GALEX observations of this sample, will result in the most
comprehensive study of merging and interacting galaxies to date.

FGS 11211

An Astrometric Calibration of Population II Distance Indicators

In 2002 HST produced a highly precise parallax for RR Lyrae. That
measurement resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a useful
result, judged by the over ten refereed citations each year since. It is,
however, unsatisfactory to have the direct, parallax-based, distance scale
of Population II variables based on a single star. We propose, therefore, to
obtain the parallaxes of four additional RR Lyrae stars and two Population
II Cepheids, or W Vir stars. The Population II Cepheids lie with the RR
Lyrae stars on a common K-band Period-Luminosity relation. Using these
parallaxes to inform that relationship, we anticipate a zero-point error of
0.04 magnitude. This result should greatly strengthen confidence in the
Population II distance scale and increase our understanding of RR Lyrae star
and Pop II Cepheid astrophysics.

WFPC2 11079

Treasury Imaging of Star Forming Regions in the Local Group: Complementing
the GALEX and NOAO Surveys

We propose to use WFPC2 to image the most interesting star-forming regions
in the Local Group galaxies, to resolve their young stellar populations. We
will use a set of filters including F170W, which is critical to detect and
characterize the most massive stars, to whose hot temperatures colors at
longer wavelengths are not sensitive. WFPC2's field of view ideally matches
the typical size of the star-forming regions, and its spatial resolution
allows us to measure indvidual stars, given the proximity of these galaxies.
The resulting H- R diagrams will enable studies of star-formation properties
in these regions, which cover largely differing metallicities {a factor of
17, compared to the factor of 4 explored so far} and characteristics. The
results will further our understanding of the star-formation process, of the
interplay between massive stars and environment, the properties of dust, and
will provide the key to interpret integrated measurements of star-formation
indicators {UV, IR, Halpha} available for several hundreds more distant
galaxies. Our recent deep surveys of these galaxies with GALEX {FUV, NUV}
and ground-based imaging {UBVRI, Halpha, [OIII] and [SII]} provided the
identification of the most relevant SF sites. In addition to our scientific
analysis, we will provide catalogs of HST photometry in 6 bands, matched
corollary ground-based data, and UV, Halpha and IR integrated measurements
of the associations, for comparison of integrated star-formation indices to
the resolved populations. We envisage an EPO component.

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 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.

NIC3 10926

GRB afterglows and host galaxies at very high redshifts

Cosmology is beginning to constrain the nature of the earliest stars and
galaxies to form in the universe, but direct observation of galaxies at z6
remains highly challenging due to their scarcity, intrinsically small size,
and high luminosity distance. GRB afterglows, thanks to their extreme
luminosities, offer the possibility of circumventing these normal
constraints by providing redshifts and spectral information which couldn't
be obtained by direct observation of the host galaxies themselves. In
addition, the association of GRBs with massive stars means that they are a
tracer of star formation, and that their hosts are likely responsible for a
large proportion of the ionizing radiation during that era. Our
collaboration is conducting a campaign to rapidly identify and study
candidate very high redshift bursts, bringing to bear a network of 2, 4 and
8m telescopes with near-IR instrumentation. Swift has proven capable of
detecting faint, distant GRBs, and reporting accurate positions for many
bursts in near real-time. Here we propose to continue our HST program of
targeting z6 GRBs. HST is crucial to this endeavour, allowing us {a} to
characterise the basic properties, such as luminosity and colour, and in
some cases morphologies, of the hosts, which is essential to understanding
these primordial galaxies and their relationship to other galaxy
populations; and {b} to monitor the late time afterglows and hence compare
them to lower-z bursts and test the use of GRBs as standard candles.

WFPC2 10916

A Study of SN Ejecta in the Core-Collapse Supernova Remnant G292.0+1.8: Cas
A's Older Cousin

Recent studies of the southern oxygen-rich supernova remnant {SNR}
G292.0+1.8 have shown it to be the only Galactic SNR to exhibit all the
features we expect in young remnants of core-collapse supernovae: an outer
shell behind an expanding primary shock, high-velocity fragments of
undiluted metal-rich ejecta, and a central pulsar surrounded by a
pulsar-wind nebula. G292.0+1.8's optical emission consists of numerous knots
and filaments of O- and S-rich ejecta spread throughout much of the remnant
shell, many with radially oriented pencil-like geometries that may trace
their origins to Rayleigh-Taylor instabilities during the SN event. The
evolution and fine-scale structure of SN debris in young remnants is poorly
understood and largely uncharted territory. For testing models for the
distribution of metal-rich ejecta from core-collapse SNe, how the ejecta
evolve and clump, and how SN shocks interact with the local circumstellar
medium, the 3000-yr-old G292.0+1.8 remnant rivals the 320-yr-old Cas A
remnant in importance. We therefore propose the first HST images of
G292.0+1.8 in order to characterize the fine-scale spatial distribution of
the ejecta, their sub-arcsecond chemical make-up, and the detailed structure
and scale lengths for metal-rich SN ejecta clumps. The proposed HST images
of G292.0+1.8 will be used in conjunction with existing Spitzer Cycle 1
infrared data and an upcoming 0.5 Msec Chandra X-ray image. We expect to
achieve the same kind of results for G292 that have already been obtained
for Cas A. High-resolution HST images of this remnant, combined with Spitzer
and Chandra data and contrasted with a similar data set on Cas A, will
provide superb multiwavelength benchmarks for both very young and older
core-collapse SNRs.

WFPC2 10903

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

We are requesting 12 HST orbits to continue to investigate the nature of the
population that gives rise to the microlensing seen towards the LMC. This
proposal builds on the cycle 14 HST program {10583} and will complement the
study with 12 yet-to-be discovered microlensing candidates from Fall 2006.
Our SuperMacho project is an ongoing ground- based survey on the CTIO 4m
that has demonstrated the ability to detect LMC microlensing events via
frame subtraction. The combination of high angular resolution and
photometric accuracy with HST will allow us to 1} confrim that the detected
flux excursions arise from LMC stars, rather than background supernovae or
AGN, and 2} obtain reliable baseline flux measurements for the objects in
their unlensed state. This latter measurement in important in determining
the microlensing optical depth towards the LMC.

WFPC2 10884

The Dynamical Structure of Ellipticals in the Coma and Abell 262 Clusters

We propose to obtain images of 13 relatively luminous early type galaxies in
the Coma cluster and Abell 262 for which we have already collected ground
based major and minor axis spectra and images. The higher resolution HST
images will enable us to study the central regions of these galaxies which
is crucial to our dynamical modelling. The complete data set will allow us
to perform a full dynamical analysis and to derive the dark matter content
and distribution, the stellar orbital structure, and the stellar population
properties of these objects, probing the predictions of galaxy formation
models. The dynamical analysis will be performed using an up-to-date
axi-symmetric orbit superposition code.

WFPC2 10834

The Shell of the Recurrent Nova T Pyx

T Pyx is the only known recurrent nova with a shell. This 'shell' is
mysterious because it has been resolved into thousands of knots that
apparently aren't expanding. We propose to take a deep F658N image of T Pyx
during one orbit to serve as a 12 year baseline from the previous HST WFPC2
images in 1994 and 1995. This much longer baseline will allow us to push
down the limits on expansion velocities to ~10 km/s and will allow us to
measure the lifetimes of the knots. Also, we expect to discover the
expanding inner shell from the last eruption in 1966 which should now have
expanded to ~0.9" in radius. Detailed modeling of the observed line fluxes
will give the mass of the individual knots and the shells. The details of
the expansion velocities, lifetimes, and masses of the knots will determine
the nature of the T Pyx shell; with alternatives being a nova shell, a
planetary nebula, stalled shocks in a pre-existing shell, or a cloud ionized
by the high luminosity and temperature of the white dwarf. If we can
separate out the mass ejected during the 1966 eruption, then we can compare
it to the total mass accreted between the 1944 and 1966 eruptions {6.0x10^-6
solar mass} so as to determine whether the white dwarf is gaining or losing
mass on average. If the white dwarf is gaining mass, then it must inevitably
exceed the Chandrasekhar mass and collapse as a Type Ia supernova, and thus
recurrent novae would be shown to be an important component of the solution
to the Type Ia progenitor problem.

WFPC2 10818

Very Young Globular Clusters in M31 ?

We propose to use HST's unique high spatial resolution imaging capabilities
to conclusively confirm or refute the presence of alleged very young
globular clusters in M31. Such young globular clusters with ages 3 Gyr are
not present in our galaxy, and, if real, would lead to a striking difference
in the age distribution of the GCs between M31 and the Millky Way. If the
apparent presence of very young globular clusters in M31 is confirmed
through our proposed ACS imaging {now WFPC2 imaging} with HST, this would
suggest major differences in the history of assembly of the two galaxies,
with probable substantial late accretion into M31 which did not occur in our
own galaxy.

WFPC2 10800

Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have
relatively fragile test particles which can be used as tracers of the early
dynamical evolution of the outer Solar System. We propose to continue a
Snapshot program using the ACS/HRC that has a demonstrated discovery
potential an order of magnitude higher than the HST observations that have
already discovered the majority of known transneptunian binaries. With this
continuation we seek to reach the original goals of this project: to
accumulate a sufficiently large sample in each of the distinct populations
collected in the Kuiper Belt to be able to measure, with statistical
significance, how the fraction of binaries varies as a function of their
particular dynamical paths into the Kuiper Belt. Today's Kuiper Belt bears
the imprints of the final stages of giant-planet building and migration;
binaries may offer some of the best preserved evidence of that long-ago era.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10875 - GSAcq(1,2,2) failed to RGA Hold (Gyro Control)

GSAcq(1,2,2), scheduled for 181/16:21:41 failed to RGA Hold (Gyro Control)
at 181/16:25:26. One 486 ESB message "a0a" (FGS Fine Lock failed-Timed out
waiting for fine lock) was received. Acquisition walkdown entered Coarse
Track (CT) multiple times before returning to default. The Primary guide
star magnitude was 11.297.

10876 - GSAcq(1,2,1) failed to RGA Hold (Gyro Control)

The GSAcq(1,2,1) scheduled at 181/18:06:44 - 18:14:19 failed to RGA Hold due
to (QF1STOPF) stop flag indication on FGS-1. Pre-acquisition OBADs were
successful. OBAD2 had (RSS) value of 14.61 arcseconds. Post-acq OBAD/MAP had
(RSS) value of 7.25 arcseconds.

COMPLETED OPS REQUEST: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 22 20
FGS REacq 13 13
OBAD with Maneuver 70 70

COMPLETED OPS NOTES: (None)

SIGNIFICANT EVENTS: (None)