Daily Report #4836

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** #4836

PERIOD COVERED: 5am April 17 - 5am April 20, 2009 (DOY
*************************** 107/0900z-110/0900z)

OBSERVATIONS SCHEDULED

WFPC2 11987

The Recent Star Formation History of SINGS Galaxies

The Spitzer Legacy project SINGS provided a unique view of the current
state of star formation and dust in a sample of galaxies of all Hubble
types. This multi-wavelength view allowed the team to create current
star formation diagnostics that are independent of the dust content
and increased our understanding of the dust in galaxies. Even so,
using the SINGS data alone we can only make rough estimates of the
recent star formation history of these galaxies. The lack of U-band
observations means that it is impossible to estimate the ages of young
clusters. In addition, the low resolution of the Spitzer and
ground-based observations means that what appear to be individual
Spitzer sources can actually be composed of many individual clusters
with varying ages. In this proposal we plan to address this missing
area in SINGS by obtaining high-resolution WFPC2 UBVI observations to
accurately find and determine the ages of the young stellar clusters
in a subset of the SINGS galaxies. These observations will greatly
enhance the legacy value of the SINGS observations while also directly
answering questions pertaining to star formation in galaxies.

ACS/SBC 11982

Spanning the Reionization History of IGM Helium: a Large and Efficient
HST Spectral Survey of Far-UV-Bright Quasars

The reionization of IGM helium is thought to have occurred at
redshifts of z=3 to 4. Detailed studies of HeII Lyman-alpha absorption
toward a handful of QSOs at 2.7z3.3 demonstrated the high potential
of such IGM probes, but the small sample size and redshift range limit
confidence in cosmological inferences. The requisite unobscured
sightlines to high-z are extremely rare, but we've cross-correlated
10, 000 z2.8 SDSS DR7 (and other) quasars with GALEX GR4 UV sources
to obtain 550 new, high confidence, sightlines potentially useful for
HST HeII studies; and in cycle 15-16 trials we demonstrated the
efficacy of our SDSS/GALEX selection approach identifying 9 new HeII
quasars at unprecedented 67% efficiency. We propose the first
far-UV-bright HeII quasar survey that is both large in scale and also
efficient, via 2-orbit reconnaissance ACS/SBC prism spectra toward a
highly select subset of 40 new SDSS/GALEX quasars at 3.1z5.1. These
will provide a community resource list that includes 5 far-UV-bright
(restframe) HeII sightlines in each of 8 redshift bins spanning
3.1z3.9 (and perhaps several objects at z4), enabling superb
post-SM4 follow-up spectra with COS or STIS. But simultaneously and
independent of any SM4 uncertainties, we will hereby directly obtain
10-orbit UV spectral stacks from the 5 HeII quasars in each of the 8
redshift bins to trace the reionization history of IGM helium over at
least 3.1z3.9. These spectral stacks will average over cosmic
variance and individual object pathology. Our new high-yield HeII
sightline sample and spectral stacks, covering a large redshift range,
will allow confident conclusions about the spectrum and evolution of
the ionizing background, the evolution of HeII opacity, the density of
IGM baryons, and the epoch of helium reionization.

WFPC2 11978

Luminous and Dark Matter in Disk Galaxies from Strong Lensing and
Stellar Kinematics

The formation of realistic disk galaxies within the LCDM paradigm is
still an unsolved problem. Theory is only now beginning to make
predictions for how dark matter halos respond to galaxy formation and
for the properties of disk galaxies. Measuring the density profiles of
dark matter halos on galaxy scales is therefore a strong test for the
standard paradigm of galaxy formation, offering great potential for
discovery. However, from an observational point of view, the
degeneracy between the stellar and dark matter contributions to galaxy
rotation curves remains a major road block. Strong gravitational
lensing, when coupled to spatially-resolved kinematics and stellar
population models, can solve this long-standing problem.
Unfortunately, this joint methodology could not be exploited so far
due to the paucity of known edge-on spiral lenses. Exploiting the full
SDSS-DR7 archive we have identified a new sample of exactly these
systems. We propose multi-color HST imaging to confirm and measure a
sample of twenty spiral lenses, covering a range of bulge to disk
ratios. By combining dynamical lensing and stellar population
information for this unique sample we will deliver the first
statistical constraints on halos and disk properties, and a new
stringent test of disk galaxy formation theories.

WFPC2 11977

WFPC2 12-Year Proper Motions of Two Galactic Analogs of the SN1987A
Rings

This special call in Cycle 16 is a unique opportunity to measure
fine-scale proper motions with the same WFPC2 camera after more than a
decade has elapsed, and is the last time such an opportunity is likely
to be available. We aim to apply this powerful tool to the ring
nebulae around two hot supergiants: the set of ionized double-rings
around the massive eclipsing binary RY Scuti, and the equatorial ring
and bipolar lobes around Sher 25. These are the only two Galactic
analogs of SN1987A for which this proper motion measurement is
possible (others lack a first-epoch image with HST, and SN1987A is too
distant). In the case of RY Scuti, the expected motions are small
because the compact ring nebula is only 1-arcsec in diameter. For Sher
25 the expected motions are small because the object is thought to be
at d=6 kpc. The 10-12 years that have elapsed since earlier imaging
epochs for these sources make it possible to accurately measure their
expected sub-pixel proper motion, and hence, their ages and distances.
We can discriminate between specific proposed models for the formation
of these ring nebulae by measuring the relative ages of these ionized
equatorial rings compared to outer structures: the bipolar lobes in
the case of Sher 25, and an outer dust shell in the case of RY Scuti.
These will provide the first quantitative tests of binary merger vs.
rapidly rotating single star models for the shaping of SN1987A and
related ring nebulae around massive stars, which until now have relied
upon qualitative comparisons to structures seen in single-epoch
images. The expected expansion is less than 0.1 arcsec, so there is no
hope of making either measurement from the ground, and increased
systematic errors associated with switching to new instruments (with
different pixel scales and distortion corrections) will make this
measurement more difficult even for HST after SM4.

WFPC2 11974

High-resolution Imaging for 9 Very Bright, Spectroscopically
Confirmed, Group-scale Lenses

There are large samples of strong lenses that probe small (galaxy)
scale masses (e.g., SLACS, SQLS, COSMOS). There are also large samples
of strong lenses that probe large (rich cluster) scale masses (e.g.,
various rich Abell clusters, the Hennawi et al. 2008 SDSS sample). The
sample of strong lenses that probe intermediate (group/cluster-core)
scale masses, however, is sparse, and so any significant additions to
this sample are important. Here we present a sample of strong lenses
that not only probe these intermediate scales but are also quite
bright, since the sample is based almost entirely upon data from the
SDSS, a relatively shallow and poor-resolution survey, at least in
comparison to most other strong lens hunting grounds, such as COSMOS
and CFHTLS. What we lack are the high-resolution imaging data needed
to construct detailed lensing models, to probe the mass and light
profiles of the lensing galaxies and their environments, and to
characterize the morphologies of the lensed (source) galaxies. Only
HST can provide these data, and so we are proposing here for 81 orbits
of deep WFPC2 F450W, F606W and F814W imaging, for 9 of our best and
brightest intermediate-scale lensing systems with known spectroscopic
redshifts and with Einstein radii between 4 and 8 arcsec.

WFPC2 11944

Binaries at the Extremes of the H-R Diagram

We propose to use HST/Fine Guidance Sensor 1r to survey for binaries
among some of the most massive, least massive, and oldest stars in our
part of the Galaxy. FGS allows us to spatially resolve binary systems
that are too faint to observe using ground-based, speckle or optical
long baseline interferometry, and too close to resolve with AO. We
propose a SNAP-style program of single orbit FGS TRANS mode
observations of very massive stars in the cluster NGC 3603, luminous
blue variables, nearby low mass main sequence stars, cool subdwarf
stars, and white dwarfs. These observations will help us to (1)
identify systems suitable for follow up studies for mass
determination, (2) study the role of binaries in stellar birth and in
advanced evolutionary states, (3) explore the fundamental properties
of stars near the main sequence-brown dwarf boundary, (4) understand
the role of binaries for X-ray bright systems, (5) find binaries among
ancient and nearby subdwarf stars, and (6) help calibrate the white
dwarf mass - radius relation.

FGS 11943

Binaries at the Extremes of the H-R Diagram

We propose to use HST/Fine Guidance Sensor 1r to survey for binaries
among some of the most massive, least massive, and oldest stars in our
part of the Galaxy. FGS allows us to spatially resolve binary systems
that are too faint for ground-based, speckle or optical long baseline
interferometry, and too close to resolve with AO. We propose a
SNAP-style program of single orbit FGS TRANS mode observations of very
massive stars in the cluster NGC 3603, luminous blue variables, nearby
low mass main sequence stars, cool subdwarf stars, and white dwarfs.
These observations will help us to (1) identify systems suitable for
follow up studies for mass determination, (2) study the role of
binaries in stellar birth and in advanced evolutionary states, (3)
explore the fundamental properties of stars near the main
sequence-brown dwarf boundary, (4) understand the role of binaries for
X-ray bright systems, (5) find binaries among ancient and nearby
subdwarf stars, and (6) help calibrate the white dwarf mass - radius
relation.

WFPC2 11603

A Comprehensive Study of Dust Formation in Type II Supernovae with
HST, Spitzer and Gemini

The recent discovery of three extremely bright Type II SNe, (2007it,
2007oc, 2007od) gives us a unique opportunity to combine observations
with HST, Spitzer and Gemini to study the little understood dust
formation process in Type II SNe. Priority 1 Spitzer Cycle 5 and band
1 Gemini 2008A time has already been approved for this project. Since
late-time Type II SNe are faint and tend to be in crowded fields, we
need the high sensitivity and high spatial resolution of ACS/HRC and
NICMOS/NIC2 for these observations. This project is motivated by the
recent detection of large amounts of dust in high redshift galaxies.
The dust in these high-z galaxies must come from young, massive stars
so Type II SNe could be potential sources. The mechanism and the
efficiency of dust condensation in Type II SN ejecta are not well
understood, largely due to the lack of observational data. We plan to
produce a unique dataset, combining spectroscopy and imaging in the
visible, near- and mid-IR covering the key phase, 400-700 days after
maximum when dust is known to form in the SN ejecta. Therefore, we are
proposing for coordinated HST/NOAO observations (HST ACS/HRC,
NICMOS/NIC2 & Gemini/GMOS and TReCS) which will be combined with our
Spitzer Cycle 5 data to study these new bright SNe. The results of
this program will place strong constraints on the formation of dust
seen in young high redshift (z5) galaxies.

FGS 11212

Filling the Period Gap for Massive Binaries

The current census of binaries among the massive O-type stars is
seriously incomplete for systems in the period range from years to
millennia because the radial velocity variations are too small and the
angular separations too close for easy detection. Here we propose to
discover binaries in this observational gap through a Faint Guidance
Sensor SNAP survey of relatively bright targets listed in the Galactic
O Star Catalog. Our primary goal is to determine the binary frequency
among those in the cluster/association, field, and runaway groups. The
results will help us assess the role of binaries in massive star
formation and in the processes that lead to the ejection of massive
stars from their natal clusters. The program will also lead to the
identification of new, close binaries that will be targets of long
term spectroscopic and high angular resolution observations to
determine their masses and distances. The results will also be
important for the interpretation of the spectra of suspected and newly
identified binary and multiple systems.

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.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11773 - GSAcq(1,2,1) at 108/14:44:39 failed to RGA control with Search
Radius Limit exceeded on FGS 1 at 108/14:50:16. REAcq(1,2,1) at
16:13:41 was successful.

Observations affected: WFPC 193 - 194, Proposal ID# 11603.

REAcq(1,2,1) at 108/17:49:33 failed with QF1SRLEX, QF1STOPF, QSRCHEXC
and QSTOP flags set at 108/17:55:04. REAcq(1,2,1) at 108/19:25:25 was
successful.

Observations affected: WFPC 198 to 201, Proposal ID# 11603

COMPLETED OPS REQUEST:

18418-1 - FSW 3.2B RAM Installation/NSSC-1 Image Load @ 106/2347z
18419-0 - FSW 3.2B EEPROM Installation @ 107/1319z
18414-1 - Install ACS FSW 5.13 (ASIC3.4), JV031 @ 109/1806z

COMPLETED OPS NOTES:

1800-1 - 486/NSSC1 SOI configuration @ 109/1645z

*********************** SCHEDULED***** SUCCESSFUL

FGS GSAcq************** 15****************** 14
FGS REAcq************** 24****************** 23
OBAD with Maneuver **** 39****************** 39

SIGNIFICANT EVENTS:

FSW 3.2 Release B was successfully installed into HST486 EEPROM at
107/11:51:28z.

ACS FSW5.13/ASIC3.4 (JV0031) was installed into EEPROM and then
activated @109/16:50z via Ops Request #18414.