Daily Report #4773

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT***** #4773

PERIOD COVERED: 5am January 15 - 5am January 16, 2009 (DOY
*************************** 015/1000z-016/1000z)

OBSERVATIONS SCHEDULED

ASC/SBC 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 z1, requiring substantial evolution
in the processes within Lyman break galaxies which allow large escape
fractions at high redshift.

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.

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.

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:

18382-4 - NCS Restart and Cooldown
18370-2 - Adjust NCS CPL Setpoint = -5.0º deg C

COMPLETED OPS NOTES: (None)

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

FGS GSacq************** 07****************** 07
FGS REacq************** 07****************** 07
OBAD with Maneuver **** 28****************** 28

SIGNIFICANT EVENTS:

Flash Report:

At 015/14:40:34 UTC, the NCC circulator was successfully restarted.