HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4702
PERIOD COVERED: 5am September 23 - 5am September 24, 2008
(DOY 267/0900z-268/0900z)
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.
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.
WFPC2 11130
AGNs with Intermediate-mass Black Holes: Testing the Black
Hole-Bulge
Paradigm, Part II
The recent progress in the study of central black holes in
galactic
nuclei has led to a general consensus that supermassive
{10^6-10^9 solar
mass} black holes are closely connected with the formation
and
evolutionary history of large galaxies, especially their
bulge
component. Two outstanding issues, however, remain
unresolved. Can
central black holes form in the absence of a bulge? And
does the mass
function of central black holes extend below 10^6 solar
masses?
Intermediate-mass black holes {<10^6 solar masses}, if
they exist, may
offer important clues to the nature of the seeds of
supermassive black
holes. Using the SDSS, our group has successfully
uncovered a new
population of AGNs with intermediate-mass black holes that
reside in
low-luminosity galaxies. However, very little is known
about the
detailed morphologies or structural parameters of the host
galaxies
themselves, including the crucial question of whether they
have bulges
or not. Surprisingly, the majority of the targets of our
Cycle 14 pilot
program have structural properties similar to dwarf
elliptical galaxies.
The statistics from this initial study, however, are
really too sparse
to reach definitive conclusions on this important new
class of black
holes. We wish to extend this study to a larger sample, by
using the
Snapshot mode to obtain WFPC2 F814W images from a parent
sample of 175
AGNs with intermediate- mass black holes selected from our
final SDSS
search. We are particularly keen to determine whether the
hosts contain
bulges, and if so, how the fundamental plane properties of
the host
depend on the mass of their central black holes. We will
also
investigate the environment of this unique class of AGNs.
WFPC2 11218
Snapshot Survey for Planetary Nebulae in Globular Clusters
of the Local
Group
Planetary nebulae {PNe} in globular clusters {GCs} raise a
number of
interesting issues related to stellar and galactic
evolution. The number
of PNe known in Milky Way GCs, 4, is surprisingly low if
one assumes
that all stars pass through a PN stage. However, it is
likely that the
remnants of stars now evolving in Galactic GCs leave the
AGB so slowly
that any ejected nebula dissipates long before the star
becomes hot
enough to ionize it. Thus there should not be ANY PNe in
Milky Way
GCs--but there are four! It has been suggested that these
PNe are the
result of mergers of binary stars within GCs, i.e., that
they are
descendants of blue stragglers. The frequency of
occurrence of PNe in
external galaxies poses more questions, because it shows a
range of
almost an order of magnitude. I propose a Snapshot survey
aimed at
discovering PNe in the GC systems of Local Group galaxies
more distant
than the Magellanic Clouds. These clusters, some of which
may be much
younger than their counterparts in the Milky Way, might
contain many
more PNe than those of our own galaxy. I will use the
standard technique
of emission-line and continuum imaging, which easily discloses
PNe.
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.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
11503 - FGS 1 & 2 Loss of Lock
At 267/09:26:02 received QF1STOPF and QF2STOPF
flags which indicated a
Loss of Lock (LOL) condition. This was
immediately followed by the
following mnemonics flagging out of limits:
FGSLOL, FGS_STAT, QSTOP,
QF1SSDIF, QF2SSDIF flags. TERM EXP was not
scheduled until 09:49:33. At
acquisition of data (09:12:55) received one 486
ESB message 1806 "T2G
Open Loop Timer Expired".
Possible observations affected:
ACS Proposal 10872, observation 1
WFPC Proposal 11796, Observations 53 - 55
11506 - GSacq(2,3,2) failed to RGA control.
During LOS GSacq(2,3,2) scheduled at
267/17:05:31 failed. At AOS
(17:17:16) stop flags were set for FGS 2.
Astromertry was scheduled so
we were in FN format.
Observations affected:WFPC 83 and 84 Proposal
ID 11796
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FAILURE TIMES
FGS GSacq 11 11
FGS REacq 03 03
OBAD with Maneuver 28 27
LOSS of LOCK 267/09:25:56z
SIGNIFICANT EVENTS:
Flash Report for NICMOS:
At ~267/12:00 NICMOS was successfully recovered to
SAAOPER, one hour
later the PAM was recovered to its intermediate position
or PAMI and the
FOM was homed. Filter wheel commands to the blank position
were
successfully blocks by the FSW. At ~267/13:13 the FW2
retry patch was
executed via SMS, the pre and post patch values were
confirmed via
memory monitors. (NICMOS science activities remain
suspended pending
recovery of the NCS post-SM4.)