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 2.7<z<3.3 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 z>2.8 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 3.1<z<5.1. These will provide a community resource list that

includes 5 far-UV-bright (restframe) HeII sightlines in each of 8

redshift bins spanning 3.1<z<3.9 (and perhaps several objects at z>4),

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 3.1<z<3.9. 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 (z>5) 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.