Daily Rpt #4919

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT #4919

PERIOD COVERED: 5am August 27 - 5am August 28, 2009 (DOY
239/09:00z-240/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC3 11465

ACS CCD Monitoring and Calibration for WFC3

This program is a smaller version of our routine CCD monitoring program,
designed to run throughout SMOV, after which our regular Cycle 17 CAL
proposal will begin. This program obtains the bias and dark frames needed to
generate reference files for calibrating science data, and allows us to
monitor detector noise and the growth of hot pixels.

FGS 11788

The Architecture of Exoplanetary Systems

Are all planetary systems coplanar? Concordance cosmogony makes that
prediction. It is, however, a prediction of extrasolar planetary system
architecture as yet untested by direct observation for main sequence stars
other than the Sun. To provide such a test, we propose to carry out FGS
astrometric studies on four stars hosting seven companions. Our
understanding of the planet formation process will grow as we match not only
system architecture, but formed planet mass and true distance from the
primary with host star characteristics for a wide variety of host stars and
exoplanet masses.

We propose that a series of FGS astrometric observations with demonstrated 1
millisecond of arc per-observation precision can establish the degree of
coplanarity and component true masses for four extrasolar systems: HD 202206
(brown dwarf+planet); HD 128311 (planet+planet), HD 160691 = mu Arae
(planet+planet), and HD 222404AB = gamma Cephei (planet+star). In each case
the companion is identified as such by assuming that the minimum mass is the
actual mass. For the last target, a known stellar binary system, the
companion orbit is stable only if coplanar with the AB binary orbit.

NIC2/WFC3/IR 11548

NICMOS Imaging of Protostars in the Orion A Cloud: The Role of
Environment in Star Formation

We propose NICMOS observations of a sample of 252 protostars identified in
the Orion A cloud with the Spitzer Space Telescope. These observations will
image the scattered light escaping the protostellar envelopes, providing
information on the shapes of outflow cavities, the inclinations of the
protostars, and the overall morphologies of the envelopes. In addition, we
ask for Spitzer time to obtain 55-95 micron spectra of 75 of the protostars.
Combining these new data with existing 3.6 to 70 micron photometry and
forthcoming 5-40 micron spectra measured with the Spitzer Space Telescope,
we will determine the physical properties of the protostars such as envelope
density, luminosity, infall rate, and outflow cavity opening angle. By
examining how these properties vary with stellar density (i.e. clusters vs
groups vs isolation) and the properties of the surrounding molecular cloud;
we can directly measure how the surrounding environment influences
protostellar evolution, and consequently, the formation of stars and
planetary systems. Ultimately, this data will guide the development of a
theory of protostellar evolution.

STIS/CCD 11844

CCD Dark Monitor Part 1

Monitor the darks for the STIS CCD.

STIS/CCD 11846

CCD Bias Monitor-Part 1

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and
1x1 at gain = 4, to build up high-S/N superbiases and track the evolution of
hot columns.

STIS/CCD 11853

Cycle 17 STIS CCD Imaging Flats

This program periodically monitors the STIS CCD imaging mode flat fields by
using the tungsten lamps.

STIS20 11402

STIS-20 NUV MAMA Dark Monitor

The STIS NUV-MAMA dark current is dominated by a phosphorescent glow from
the detector window. Meta-stable states in this window are populated by
cosmic ray impacts, which, days later, can be thermally excited to an
unstable state from which they decay, emitting a UV photon. The equilibrium
population of these meta-stable states is larger at lower temperatures; so
warming up the detector from its cold safing will lead to a large, but
temporary, increase in the dark current.

To monitor the decay of this glow, and to determine the equilibrium dark
current for Cycle 17, four 1380s NUV-MAMA ACCUM mode darks should be taken
each week during the SMOV period. Once the observed dark current has reached
an approximate equilibrium with the mean detector temperature, the frequency
of this monitor can be reduced to one pair of darks per week.

WFC3/ACS/IR 11563

Galaxies at z~7-10 in the Reionization Epoch: Luminosity Functions to 0.2L*
from Deep IR Imaging of the HUDF and HUDF05 Fields

The first generations of galaxies were assembled around redshifts z~7-10+,
just 500-800 Myr after recombination, in the heart of the reionization of
the universe. We know very little about galaxies in this period. Despite
great effort with HST and other telescopes, less than ~15 galaxies have been
reliably detected so far at z7, contrasting with the ~1000 galaxies
detected to date at z~6, just 200-400 Myr later, near the end of the
reionization epoch. WFC3 IR can dramatically change this situation, enabling
derivation of the galaxy luminosity function and its shape at z~7-8 to well
below L*, measurement of the UV luminosity density at z~7-8 and z~8-9, and
estimates of the contribution of galaxies to reionization at these epochs,
as well as characterization of their properties (sizes, structure, colors).
A quantitative leap in our understanding of early galaxies, and the
timescales of their buildup, requires a total sample of ~100 galaxies at
z~7-8 to ~29 AB mag. We can achieve this with 192 WFC3 IR orbits on three
disjoint fields (minimizing cosmic variance): the HUDF and the two nearby
deep fields of the HUDF05. Our program uses three WFC3 IR filters, and
leverages over 600 orbits of existing ACS data, to identify, with low
contamination, a large sample of over 100 objects at z~7-8, a very useful
sample of ~23 at z~8-9, and limits at z~10. By careful placement of the WFC3
IR and parallel ACS pointings, we also enhance the optical ACS imaging on
the HUDF and a HUDF05 field. We stress (1) the need to go deep, which is
paramount to define L*, the shape, and the slope alpha of the luminosity
function (LF) at these high redshifts; and (2) the far superior performance
of our strategy, compared with the use of strong lensing clusters, in
detecting significant samples of faint z~7-8 galaxies to derive their
luminosity function and UV ionizing flux. Our recent z~7.4 NICMOS results
show that wide-area IR surveys, even of GOODS-like depth, simply do not
reach faint enough at z~7-9 to meet the LF and UV flux objectives. In the
spirit of the HDF and the HUDF, we will waive any proprietary period, and
will also deliver the reduced data to STScI. The proposed data will provide
a Legacy resource of great value for a wide range of archival science
investigations of galaxies at redshifts z~2-9. The data are likely to remain
the deepest IR/optical images until JWST is launched, and will provide
sources for spectroscopic followup by JWST, ALMA and EVLA.

WFC3/ACS/UVIS 11360

Star Formation in Nearby Galaxies

Star formation is a fundamental astrophysical process; it controls phenomena
ranging from the evolution of galaxies and nucleosynthesis to the origins of
planetary systems and abodes for life. The WFC3, optimized at both UV and IR
wavelengths and equipped with an extensive array of narrow-band filters,
brings unique capabilities to this area of study. The WFC3 Scientific
Oversight Committee (SOC) proposes an integrated program on star formation
in the nearby universe which will fully exploit these new abilities. Our
targets range from the well-resolved R136 in 30 Dor in the LMC (the nearest
super star cluster) and M82 (the nearest starbursting galaxy) to about half
a dozen other nearby galaxies that sample a wide range of star-formation
rates and environments. Our program consists of broad band multiwavelength
imaging over the entire range from the UV to the near-IR, aimed at studying
the ages and metallicities of stellar populations, revealing young stars
that are still hidden by dust at optical wavelengths, and showing the
integrated properties of star clusters. Narrow-band imaging of the same
environments will allow us to measure star-formation rates, gas pressure,
chemical abundances, extinction, and shock morphologies. The primary
scientific issues to be addressed a (1) What triggers star formation? (2)
How do the properties of star-forming regions vary among different types of
galaxies and environments of different gas densities and compositions? (3)
How do these different environments affect the history of star formation?
(4) Is the stellar initial mass function universal or determined by local
conditions?

WFC3/IR 11915

IR Internal Flat Fields

This program is the same as 11433 (SMOV) and depends on the completion of
the IR initial alignment (program 11425). This version contains three
instances of 37 internal orbits; to be scheduled early, middle, and near the
end of Cycle 17, in order to use the entire 110-orbit allocation.

In this test, we will study the stability and structure of the IR channel
flat field images through all filter elements in the WFC3-IR channel. Flats
will be monitored, i.e. to capture any temporal trends in the flat fields,
and delta flats produced. High signal observations will provide a map of the
pixel-to-pixel flat field structure, as well as identify the positions of
any dust particles.

WFC3/UVIS 11565

A Search for Astrometric Companions to Very Low-Mass, Population II
Stars

We propose to carry out a SNAPshot search for astrometric companions in a
subsample of very low-mass, halo subdwarfs identified within 120 parsecs of
the Sun. These ultra- cool M subdwarfs are local representatives of the
lowest-mass H burning objects from the Galactic Population II. The expected
3-4 astrometric doubles that will be discovered will be invaluable in that
they will be the first systems from which gravitational masses of metal-poor
stars at the bottom of the main sequence can be directly measured.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set of
full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K subarray
biases are acquired at less frequent intervals throughout the cycle to
support subarray science observations. The internals from this proposal,
along with those from the anneal procedure (11909), will be used to generate
the necessary superbias and superdark reference files for the calibration
pipeline (CDBS).

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the UVIS
detector (both CCDs) at the level of ~1%, lasting hours to days. Initially
found via an unexpected bowtie-shaped feature in flatfield ratios,
subsequent lab tests on similar e2v devices have since shown that it is also
present as simply an overall offset across the entire CCD, i.e., a QE offset
without any discernable pattern. These lab tests have further revealed that
overexposing the detector to count levels several times full well fills the
traps and effectively neutralizes the bowtie. Each visit in this proposal
acquires a set of three 3x3 binned internal flatfields: the first
unsaturated image will be used to detect any bowtie, the second, highly
exposed image will neutralize the bowtie if it is present, and the final
image will allow for verification that the bowtie is gone.

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: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSAcq 7 7
FGS REAcq 8 8
OBAD with Maneuver 5 5

SIGNIFICANT EVENTS: (None)