HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4623
PERIOD
COVERED: 5am June 02 - 5am June 03, 2008 (DOY 154/0900z-155/0900z)
OBSERVATIONS
SCHEDULED
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.
NIC1/NIC2/NIC3
8794
NICMOS Post-SAA calibration - CR Persistence Part 5
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 DARKs. 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
images.
Each observation will need its own CRMAP, as different SAA
passages
leave different imprints on the NICMOS detectors.
NIC2
11123
A NICMOS
Survey for Proplyds in the RCW 38 Massive Embedded Cluster
We
propose a search for line emission from photoevaporating
protoplanetary
disks in the Massive Embedded Cluster RCW 38. These disks
would
be analogous to the "proplyds" discovered in the Orion Nebula:
disks
around young low mass stars which are being photoionized by a
nearby
O star. We will search for these disks in RCW 38 using narrowband
imaging
in the lines of Paschen alpha and molecular hydrogen (1-0) S(1)
with
NICMOS. The RCW 38 region is an excellent target for determining
whether
proplyds are observable in large numbers outside of Orion. It is
a
young embedded cluster hosting a few hundred low mass young stars with
a
large percentage showing infrared excess indicating the presence of
disks.
About 100 of these stars are found within 0.1 pc of the central
O5
star, and the cluster is located within a cleared cavity 0.2 pc in
size,
embedded within a molecular cloud, exposing the cluster members
directly
to the UV radiation from the O star. Unlike Orion, but like
many
other young clusters, RCW 38 is not seen in visible light, and
infrared
imaging is needed. The best line in the infrared for revealing
proplyds
is the Paschen alpha line, which is not detectable from the
ground.
Only HST is able to perform these observations. From these
observations
we will estimate the lifetime of the evaporating disks, and
ascertain
whether these disks will survive long enough to form planets.
NIC2
11164
Molecular
Hydrogen Disks Around T Tauri Stars
We propose
to measure the properties of planetary system-sized disks
around
Sun- like, pre-main sequence stars by imaging the inner parts of
these
disks for the first time in gaseous emission from their most
dominant constituent, molecular hydrogen gas. Specifically, we
will use
the
F212N filter and NICMOS to determine the spatial distribution of
ro-vibrational
H2 emission from protoplanetary disks around selected
classical
and weak-lined T Tauri stars. The target stars are among those
detected
by members of this team through high resolution, ground-based
infrared
spectroscopy. The spectra reveal H2 emission at the rest
velocities
of the stars and at positions spatially coincident with the
stars
at the spatial resolution of the spectroscopic data. This imaging
experiment,
which is impossible to do using ground- based facilities, is
possible
using the NICMOS camera aboard the HST because the point spread
function
of this system is extremely stable and can be measured to a
very
high accuracy. This experiment is an important test of the
interpretation
that the 2.122 micron H2 line emission seen toward T
Tauri
stars is produced at distances of 10 to 30 AU from the stars, the
region
in which giant planets are expected to form around these stars.
These
observations will contribute toward developing a better
understanding
of the process, likelihood, and timescale for the
formation
of planets around Sun-like stars.
WFPC2
11029
WFPC2
CYCLE 15 Intflat Linearity Check and Filter Rotation Anomaly
Monitor
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 xxxx 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.
WFPC2
11227
The
Orbital Period for an Ultraluminous X-ray Source in NGC1313
The
ultraluminous X-ray sources {ULXs} are extragalactic point sources
with
luminosities that exceed the Eddington luminosity for conventional
stellar-mass
black holes by factors of 10 - 100. It has been hotly
debated
whether the ULXs are just common stellar-mass black hole sources
with
beamed emission or whether they are sub-Eddington sources that are
powered
by the long-sought intermediate mass black holes {IMBH}. To
firmly
decide this question, one must obtain dynamical mass measurements
through
photometric and spectroscopic monitoring of the secondaries of
these
system. The crucial first step is to establish the orbital period
of
a ULX, and arguably the best way to achieve this goal is by
monitoring
its ellipsoidal light curve. The extreme ULX NGC1313 X-2
provides
an outstanding target for an orbital period determination
because
its relatively bright optical counterpart {V = 23.5} showed a
15%
variation between two HST observations separated by three months.
This
level of variability is consistent with that expected for a tidally
distorted
secondary star. Here we propose a set of 20 imaging
observations
with HST/WFPC2 to define the orbital period. This would be
the
first photometric measurement of the orbital period of a ULX binary.
Subsequently,
we will propose to obtain spectroscopic observations to
obtain
its radial velocity amplitude and thereby a dynamical estimate of
its
mass.
WFPC2
11337
Investigating
the X-ray Variability of Cassiopeia A
We
propose a 50 ksec ACIS-S observation of Cas A to follow X-ray flux
changes
associated with ejecta recently encountered by the reverse
shock.
This will allow us to investigate Cas A's near-term X-ray
evolution
and the fine-scale structure of its SN debris. We also request
the
Chandra observation be followed by HST NICMOS & WFPC2 images of four
identified
X-ray variable features in the high ionization NIR lines of
[Si
VI] and [Si X] and low ionization optical lines of [S II]
and [O
III].
The proposed X-ray/optical/NIR observations will yield a
multi-wavelength
study of the remnant's advancing reverse shock in an
inhomogeneous
multi-phase ejecta medium at resolutions down to a
fraction
of an arcsecond, providing a hi-resolution broad temperature
study
of reverse shock heated SN ejecta.
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
08
08
FGS
REacq
02
02
OBAD
with Maneuver
20
20
SIGNIFICANT
EVENTS: (None)