HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      #4764

PERIOD COVERED: 5am January 2 - 5am January 5, 2009 (DOY

                           002/1000z-005/1000z)

OBSERVATIONS SCHEDULED

WFPC2 11966

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 high resolution

observations (especially U-band and H-alpha) 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. We need to know the ages, star

formation histories, and extinction of these individual clusters to

understand how these clusters form and age and thus influence the

evolution of the galaxy. In this proposal we address this missing area

of SINGS by obtaining high-resolution WFPC2 UBVI & H-alpha observations

to not only accurately locate and determine the ages of the young

stellar clusters in the actively star forming SINGS galaxies but to also

address a variety of other scientific issues. Over 500 HST orbits and

500 hours of Spitzter observing time have been dedicated to observations

of the SINGS sample. But the HST observations have not been systematic.

By adding a relatively small fraction of this time for these requested

observations, we will greatly enhance the legacy value of the SINGS

observations by creating a uniform high resolution multi-wavelength HST

archive that matches the quality of the lower resolution SINGS archive.

WFPC2 11962

A New Supernova in the Antennae; Narrowing in on the Hubble Constant and

Dark Energy

A measurement of the Hubble constant to a precision of a few percent

would be a powerful aid to the investigation of the nature of dark

energy and a potent "end-to-end" test of the present cosmological model.

In Cycle 15 we constructed a new, streamlined distance ladder utilizing

high-quality type Ia supernova data and observations of Cepheids with

HST in the near-IR to minimize the dominant sources of systematic

uncertainty in past measurements of the Hubble constant and reduce its

total uncertainty to a little under 5%. Here we propose to exploit this

new route with a rare opportunity to begin reducing the remaining

uncertainty. SN 2007sr in the Antennae (NGC 4038/9) is the rare SN Ia

which is suitable for increasing the precision of small calibration

sample of SNe Ia. Even rarer is that it is close enough that it's

Cepheids are within range of observing with WFPC2 (and NICMOS, should it

return to life). But we need to act fast as the window of long

visibility and fixed orient runs from mid-early December 2008 to early

March 2009. We request 34 orbits with WFPC2 to find the Cepheids in the

SN host. We also request 16 orbits to observe the Cepheids we find with

Camera 2, F160W if NICMOS becomes available by April 2009 . (If NICMOS

does not return we would forgo these observations and ask the TTRB to

let us make them with our own WFC3-IR allocation, though we much prefer

the smaller pixel size of NIC2).

FGS 11945

Asteroseismology of Extrasolar Planet Host Stars

Detections of stellar oscillations, although a very demanding task in

terms of observing time, offers a return of more accurate knowledge

about the structure of stars than can be obtained in any other way. In

particular, detecting the 10-15 highest amplitude modes in solar-like

stars to signal-to-noise of just a few sigma each allows robust

constraints on the stellar density to <1%, and the stellar age to within

5-10% of its main sequence lifetime. Ten day observing runs using the

FGS as a photometer on any of the 5 best transiting planet systems would

enable these asteroseismology returns. From more precisely observed

transit shapes than can be obtained from the ground a completely

independent constraint on stellar density to ~1% can be obtained. The

long observation sets required for asteroseismology also provide an

excellent opportunity of detecting transits from other planets, e.g.

hypothesized inner -orbit Hot Earths, should any exist.

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 11797

Supplemental WFPC2 CYCLE 16 Intflat Linearity Check and Filter Rotation

Anomaly Monitor

Supplemental observations to 11029, to cover period from Aug 08 to SM4.

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 11022 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.

Note: These are supplemental observations to cover June to SM4 (Oct 8

'08) + 6 months.

WFPC2 11796

WFPC2 Cycle 16 Decontaminations and Associated Observations

This proposal is for the WFPC2 decons. Also included are instrument

monitors tied to decons: photometric stability check, focus monitor,

pre- and post-decon internals (bias, intflats, kspots, & darks), UV

throughput check, VISFLAT sweep, and internal UV flat check.

WFPC2 11795

WFPC2 Cycle 16 UV Earth Flats

Monitor flat field stability. This proposal obtains sequences of earth

streak flats to improve the quality of pipeline flat fields for the

WFPC2 UV filter set. These Earth flats will complement the UV earth flat

data obtained during cycles 8-15.

FGS 11789

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.

FGS 11704

The Ages of Globular Clusters and the Population II Distance Scale

Globular clusters are the oldest objects in the universe whose age can

be accurately determined. The dominant error in globular cluster age

determinations is the uncertain Population II distance scale. We propose

to use FGS 1r to obtain parallaxes with an accuracy of 0.2

milliarcsecond for 9 main sequence stars with [Fe/H] < -1.5. This will

determine the absolute magnitude of these stars with accuracies of 0.04

to 0.06mag. This data will be used to determine the distance to 24

metal-poor globular clusters using main sequence fitting. These

distances (with errors of 0.05 mag) will be used to determine the ages

of globular clusters using the luminosity of the subgiant branch as an

age indicator. This will yield absolute ages with an accuracy 5%, about

a factor of two improvement over current estimates. Coupled with

existing parallaxes for more metal-rich stars, we will be able to

accurately determine the age for globular clusters over a wide range of

metallicities in order to study the early formation history of the Milky

Way and provide an independent estimate of the age of the universe.

The Hipparcos database contains only 1 star with [Fe/H] < -1.4 and an

absolute magnitude error less than 0.18 mag which is suitable for use in

main sequence fitting. Previous attempts at main sequence fitting to

metal-poor globular clusters have had to rely on theoretical

calibrations of the color of the main sequence. Our HST parallax program

will remove this source of possible systematic error and yield distances

to metal-poor globular clusters which are significantly more accurate

than possible with the current parallax data. The HST parallax data will

have errors which are 10 times smaller than the current parallax data.

Using the HST parallaxes, we will obtain main sequence fitting distances

to 11 globular clusters which contain over 500 RR Lyrae stars. This will

allow us to calibrate the absolute magnitude of RR Lyrae stars, a

commonly used Population II distance indicator.

ACS/SBC 11681

A Search for Ultraviolet Emission Filaments in Cool Core Clusters

We propose to use ACS SBC imaging to seek ultraviolet CIV emission

filaments in clusters of galaxies exhibiting strong cool-core X-ray

emission and optical line emission filaments. These short observations

are crafted to test thermal conduction models for the filament

excitation, and can significantly impact our understanding of the

overall physical processes dominant in the galaxy cluster ISM.

WFPC2 11612

Eta Carinae's Continuing Instability and Recovery - the 2009 Event

Eta Carinae is the only really observable example of structural recovery

from a massive giant eruption, a "supernova imposter' event. Moreover it

is the only well-observed star above 100 Msun, and its

5.5-year-recurrent spectroscopic events provide extraordinary clues to

its surface instability. This truly unique combination of attributes

makes it valuable for understanding the most massive stars. A fresh

development arose a few years ago: The star has brightened much faster

than before, and appears to have entered a rapid stage in its

post-eruption recovery.

A spectroscopic event will occur at 2009.0, soon after the planned HST

servicing mission. Because of the recent secular trend, this event is

expected to differ from its well-observed 2003.5 predecessor. The

differences will be very important, because they offer clues to

very-massive-star structural instabilities that can't be observed in any

other known way.

Some of the needed observations require HST's high spatial resolution

and UV coverage. We propose an efficient, well-chosen set of STIS and

ACS observations around the critical time. If the servicing mission is

too late for the event, then a subset of the observations will still be

merited.

ACS/SBC 11579

The Difference Between Neutral- and Ionized-Gas Metal Abundances in

Local Star-Forming Galaxies with COS

The metallicity of galaxies and its evolution with redshift is of

paramount importance for understanding galaxy formation. Abundances in

the interstellar medium (ISM) are typically determined using

emission-line spectroscopy of HII regions. However, since HII regions

are associated with recent SF they may not have abundances typical for

the galaxy as a whole. This is true in particular for star-forming

galaxies (SFGs), in which the bulk of the metals may be contained in the

neutral gas. It is therefore important to directly probe the metal

abundances in the neutral gas. This can be done using absorption lines

in the Far UV. We have developed techniques to do this in SFGs, where

the absorption is measured for sightlines toward bright SF regions

within the galaxy itself. We have successfully applied this technique to

a sample of galaxies observed with FUSE. The results have been very

promising, suggesting in I Zw 18 that abundances in the neutral gas may

be up to 0.5 dex lower than in the ionized gas. However, the

interpretation of the FUSE data is complicated by the very large FUSE

aperture (30 arcsec), the modest S/N, and the limited selection of

species available in the FUSE bandpass. The advent of COS on HST now

allows a significant advance in all of these areas. We will therefore

obtain absorption line spectroscopy with G130M in the same sample for

which we already have crude constraints from FUSE. We will obtain

ACS/SBC images to select the few optimal sightlines to target in each

galaxy. The results will be interpreted through line-profile fitting to

determine the metal abundances constrained by the available lines. The

results will provide important new insights into the metallicities of

galaxies, and into outstanding problems at high redshift such as the

observed offset between the metallicities of Lyman Break Galaxies and

Damped Lyman Alpha systems.

NIC3 11236

Did Rare, Large Escape-Fraction Galaxies Reionize the Universe?

Lyman continuum photons produced in massive starbursts may have played a

dominant role in the reionization of the Universe. Starbursts are

important contributors to the ionizing metagalactic background at lower

redshifts as well. However, their contribution to the background depends

upon the fraction of ionizing radiation that escapes from the intrinsic

opacity of galaxies below the Lyman limit. Current surveys suggest that

the escape fraction is close to zero in most galaxies, even among young

starbursts, but is large in 15-25% of them. Non-uniform escape fractions

are expected as a result of violent events creating clear paths in small

parts of galaxies. The number of galaxies observed with high escape

fraction will result from the combination of the intrinsic number with

clear lines of sight and their orientation with respect to the observer.

We propose to measure the fraction of escaping Lyman continuum radiation

in a large sample (47) of z~0.7 starbursts in the COSMOS field. These

compact UV-luminous galaxies are good analogs to high redshift LBGs.

Using the SBC/PR130L we can quickly (1-4 orbits) detect relative escape

fractions (f_LC/f_1500) of 25% or more. This will be the first

measurement of the escape fraction in sources between z=1 and the local

universe. We expect ~10 detections. Stacking will set limits of <4% on

the relative escape fraction in the rest. We will correlate the LC

detections with the properties of the galaxies. By targeting z~0.7 in

COSMOS, we will have tremendous ancillary information on those sources.

A non-detection in all sources would be significant (99% confidence).

This would imply that QSOs provide the overwhelming majority of ionizing

radiation at z<1, requiring substantial evolution in the processes

within Lyman break galaxies which allow large escape fractions at high

redshift.

FGS 11213

Distances to Eclipsing M Dwarf Binaries

We propose HST FGS observations to measure accurate distances of 5

nearby M dwarf eclipsing binary systems, from which model-independent

luminosities can be calculated. These objects have either poor or no

existing parallax measurements. FGS parallax determinations for these

systems, with their existing dynamic masses determined to better than

0.5%, would serve as model-independent anchor points for the low-mass

end of the mass-luminosity diagram.

ACS/SBC 11158

HST Imaging of UV Emission in Quiescent Early-type Galaxies

We have constructed a sample of early type galaxies at z~0.1 that have

blue UV-optical colors, yet also show no signs of optical emission, or

extended blue light. We have cross-correlated the SDSS catalog and the

Galaxy Evolution Explorer Medium Imaging Survey to select a sample of

galaxies where this UV emission is strongest. The origin of the UV

rising flux in these galaxies continues to be debated, and the

possibility that some fraction of these galaxies may be experiencing low

levels of star formation cannot be excluded. There is also a possibility

that low level AGN activity {as evidenced by a point source} is

responsible We propose to image the UV emission using the HST/SBC and to

explore the morphology of the UV emission relative to the optical light.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS:

11627 - GSacq(1,2,1) failed

            During LOS GSacq(1,2,1) scheduled at 003/11:46:42 failed to RGA hold.

            Observation affected: WFPC 128-132 Proposal ID#11797

11628 - REacq(1,2,1) failed

           The REacq(1,2,1) scheduled at 003/13:17:23 failed at 13:21:33.

           Observations affected: ACS 8 Proposal ID#11236

11629 - GSAcq(1,2,2) failed

           GSAcq(1,2,2) scheduled at 005/08:24:27 - 08:32:32 failed to RGA Hold.

           Subsequent REacq(1,2,2) scheduled at 005/10:00:06 was successful.

           Observations affected: WFPC 19 thru 21 Proposal ID#11966

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                          SCHEDULED      SUCCESSFUL    

FGS GSacq                 19                   17

FGS REacq                 21                   20                   

OBAD with Maneuver  80                    80                  

SIGNIFICANT EVENTS: (None)