HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4677
PERIOD COVERED: 5am August 18 - 5am August 19, 2008 (DOY
231/0900z-232/0900z)
OBSERVATIONS SCHEDULED
ACS/SBC 10872
Lyman Continuum Emission in Galaxies at z=1.2
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
escape fractions of a few percent, up to 10%, with very
few detections
{as opposed to upper limits} having been reported. No
detections have
been reported in the epochs between z=0.1 and z=2. We
propose to measure
the fraction of escaping Lyman continuum radiation from 15
luminous
z~1.2 galaxies in the GOODS fields. Using the tremendous
sensitivity of
the ACS Solar-blind Channel, we will reach AB=30 mag.,
allowing us to
detect an escape fraction of 1%. We will correlate the
amount of
escaping radiation with the photometric and morphological
properties of
the galaxies. A non-detection in all sources would imply
that QSOs
provide the overwhelming majority of ionizing radiation at
z=1.3, and it
would strongly indicate that the properties of galaxies at
higher
redshift have to be significantly different for galaxies
to dominate
reionization. The deep FUV images will also be useful for
extending the
FUV study of other galaxies in the GOODS fields.
NIC1/NIC2 11172
Defining Classes of Long Period Variable Stars in M31
We propose a thrifty but information-packed investigation
{1440
exposures total} with NICMOS F205W, F160W and F110W
providing crucial
information about Long Period Variables in M31, at a level
of detail
that has recently allowed the discovery of new variable
star classes in
the Magellanic Clouds, a very different stellar
population. These
observations are buttressed by an extensive map of the
same fields with
ACS and WFPC2 exposures in F555W and F814W, and a massive
ground-based
imaging patrol producing well-sampled light curves for
more than 400,000
variable stars. Our primary goal is to collect sufficient
NIR data in
order to analyze and classify the huge number of
long-period variables
in our catalog {see below} through Period-Luminosity {P/L}
diagrams. We
will produce accurate P/L diagrams for both the bulge and
a progression
of locations throughout the disk of M31. These diagrams
will be similar
in quality to those currently in the Magellanic Clouds,
with their lower
metallicity, radically different star formation history,
and larger
spread in distance to the variables. M31 offers an
excellent chance to
study more typical disk populations, in a manner which
might be extended
to more distant galaxies where such variables are still
visible, probing
a much more evenly spread progenitor age distribution than
cepheids {and
perhaps useful as a distance scale alternative or
cross-check}. Our data
will also provide a massive and unique color-magnitude
dataset, and
allow us to confirm the microlensing nature of a large
sample of
candidate lensed sources in M31. We expect that this study
will produce
several important results, among them a better
understanding of P/L and
P/L-color relations for pulsating variables which are
essential to the
extragalactic distance ladder, will view these variables at
a common
distance over a range of metallicities {eliminating the
distance- error
vs. metallicity ambiguity between the LMC and SMC}, allow
further
insight into possible faint-variable mass-loss for higher
metallicities,
and in general produce a sample more typical of giant disk
galaxies
predominant in many studies.
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA Calibration - CR Persistence Part 6
A new procedure proposed to alleviate the CR-persistence
problem of
NICMOS. Dark frames will be obtained immediately upon
exiting the SAA
contour 23, and every time a NICMOS exposure is scheduled
within 50
minutes of coming out of the SAA. The darks will be
obtained in parallel
in all three NICMOS Cameras. The POST-SAA darks will be
non-standard
reference files available to users with a USEAFTER
date/time mark. The
keyword 'USEAFTER=date/time' will also be added to the
header of each
POST-SAA DARK frame. The keyword must be populated with
the time, in
addition to the date, because HST crosses the SAA ~8 times
per day so
each POST-SAA DARK will need to have the appropriate time
specified, for
users to identify the ones they need. Both the raw and
processed images
will be archived as POST-SAA DARKSs. Generally we expect
that all NICMOS
science/calibration observations started within 50 minutes
of leaving an
SAA will need such maps to remove the CR persistence from
the science i
mages. Each observation will need its own CRMAP, as
different SAA
passages leave different imprints on the NICMOS detectors.
NIC2 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.
NIC3/WFPC2 11192
NICMOS Confirmation of Candidates of the Most Luminous
Galaxies at z > 7
While the deepest pencil-beam near-IR survey suggested
that the Universe
was too young to build up many luminous galaxies by z ~
7--8 (Bouwens &
Illingworth 2006), there is also evidence indicating the
contrary. It is
now known that some galaxies with stellar masses of
M>1e10 Msun were
already in place by z ~ 6--7, which strongly suggests that
their
progenitors should be significantly more luminous, and
hence detectable
in deep, wide-field near-IR surveys (Yan et al. 2006). As
galaxies at
such a high redshift should manifest themselves as
"dropouts" from the
optical, we have carried out a very wide-field, deep
near-IR survey in
the GOODS fields to search for z-band dropouts as candidates
of galaxies
at z > 7. In total, six promising candidates have been
found in ~ 300
sq. arcmin to J_AB ~ 24.5 mag (corresponding to restframe
M(UV) < -22.5
mag at z ~ 7). By contrast, the galaxy luminosity function
(LF)
suggested in BI06 would predict at most 3--5 galaxies over
the entire
2-pi sky at this brightness level. Here we propose to
observe these
candidates with NIC3 in F110W and F160W to further
investigate their
nature. If any of these candidates are indeed at z > 7,
the result will
lead to a completely new picture of star formation in the
early
universe. If none of our candidates are consistent with
being at z > 7,
then the depth and area of our near-IR survey (from which
the candidates
are drawn) will let us set a very stringent upper limit on
the bright
end of the galaxy LF at those redshift. As a result, our
program will
still be able to provide new clues about the processes of
early galaxy
formation, such as their dust contents and their merging
time scale (Yan
et al. 2006).
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.
WFPC2 11203
A Search for Circumstellar Disks and Planetary-Mass
Companions around
Brown Dwarfs in Taurus
During a 1-orbit program in Cycle 14, we used WFPC2 to
obtain the first
direct image of a circumstellar disk around a brown dwarf.
These data
have provided fundamental new constraints on the formation
process of
brown dwarfs and the properties of their disks. To search
for additional
direct detections of disks around brown dwarfs and to
search for
planetary-mass companions to these objects, we propose a
WFPC2 survey of
32 brown dwarfs in the Taurus star-forming region.
WFPC2 11235
HST NICMOS Survey of the Nuclear Regions of Luminous
Infrared Galaxies
in the Local Universe
At luminosities above 10^11.4 L_sun, the space density of
far-infrared
selected galaxies exceeds that of optically selected
galaxies. These
`luminous infrared galaxies' {LIRGs} are primarily
interacting or
merging disk galaxies undergoing enhanced star formation
and Active
Galactic Nuclei {AGN} activity, possibly triggered as the
objects
transform into massive S0 and elliptical merger remnants.
We propose
NICMOS NIC2 imaging of the nuclear regions of a complete
sample of 88
L_IR > 10^11.4 L_sun luminous infrared galaxies in the
IRAS Revised
Bright Galaxy Sample {RBGS: i.e., 60 micron flux density
> 5.24 Jy}.
This sample is ideal not only in its completeness and
sample size, but
also in the proximity and brightness of the galaxies. The
superb
sensitivity and resolution of NICMOS NIC2 on HST enables a
unique
opportunity to study the detailed structure of the nuclear
regions,
where dust obscuration may mask star clusters, AGN and
additional nuclei
from optical view, with a resolution significantly higher
than possible
with Spitzer IRAC. This survey thus provides a crucial
component to our
study of the dynamics and evolution of IR galaxies
presently underway
with Wide-Field, HST ACS/WFC and Spitzer IRAC observations
of these 88
galaxies. Imaging will be done with the F160W filter
{H-band} to examine
as a function of both luminosity and merger stage {i} the
luminosity and
distribution of embedded star clusters, {ii} the presence
of optically
obscured AGN and nuclei, {iii} the correlation between the
distribution
of 1.6 micron emission and the mid-IR emission as detected
by Spitzer
IRAC, {iv} the evidence of bars or bridges that may funnel
fuel into the
nuclear region, and {v} the ages of star clusters for
which photometry
is available via ACS/WFC observations. The NICMOS data,
combined with
the HST ACS, Spitzer, and GALEX observations of this
sample, will result
in the most comprehensive study of merging and interacting
galaxies to
date.
WFPC2 11302
WFPC2 CYCLE 16 Standard Darks - Part III
This dark calibration program obtains dark frames every
week in order to
provide data for the ongoing calibration of the CCD dark
current rate,
and to monitor and characterize the evolution of hot
pixels. Over an
extended period these data will also provide a monitor of
radiation
damage to the CCDs.
WFPC2 11793
WFPC2 Cycle 16 Internal Monitor
This calibration proposal is the Cycle 15 routine internal
monitor for
WFPC2, to be run weekly to monitor the health of the
cameras. A variety
of internal exposures are obtained in order to provide a
monitor of the
integrity of the CCD camera electronics in both bays (both
gain 7 and
gain 15 -- to test stability of gains and bias levels), a
test for
quantum efficiency in the CCDs, and a monitor for possible
buildup of
contaminants on the CCD windows. These also provide raw
data for
generating annual super-bias reference files for the calibration
pipeline.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
11448 - GSACQ(2,0,2) failed while LOS
Upon acquisition of signal at 231/21:31:14 vehicle was in gyro control
with QF2STOPF and QSTOP flags set. GSACQ(2,0,2) at 21:11:27 failed to
RGA control. #44 commands did not change since previous acquisition.
Observations affected: NICMOS 38 to 40, proposal 11548.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq
10
09
FGS
REacq 05
05
OBAD with Maneuver
28
28
SIGNIFICANT EVENTS: (None)