HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #
4557
PERIOD COVERED: UT February 28, 2008 (DOY 059)
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.
FGS 11301
Dynamical Masses and Radii of Four White Dwarf Stars
This proposal uses the FGS1r in TRANS
mode to resolve a pair of double
degenerate binary
systems {WD1639+153 and WD 1818+26} in order to
determine their
orbital elements. In addition, the binaries and several
nearby field
stars are observed by FGS1r in POS mode to establish the
local
inertial reference frame of each binary, as well as its parallax
and proper
motion. This will allow for a direct measurement of the
distance and
radius of each of the four WD stars. When combined with the
orbital
elements, this leads to a dynamical mass measurement for each
WD, and a four calibration points of
the WD mass-radius relation.
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 11135
Extreme makeovers: Tracing the transformation of massive
galaxies at
z~2.5
To obtain a full spectroscopic census of the universe at
z~2.5 we have
conducted a
near-infrared spectroscopic survey for K-selected galaxies.
We found that, in contrast to the local universe, massive
high-redshift
galaxies span a
wide range of properties, varying from (dusty) star
burst to
"red and dead" galaxies. This may imply that massive galaxies
transform from
star-forming to quiescent galaxies in the targeted
redshift range.
To understand whether the 9 quiescent galaxies in our
sample are the
progenitors of local elliptical, we are observing them in
the current
cycle with NIC2. For cycle 16 we propose to complete our
sample of
massive z~2.5 galaxies and image the remaining 10 galaxies,
which all
have emission lines. Based on emission-line diagnostics, 6 of
these
galaxies are identified as star-forming objects and 4 harbor an
active
galactic nucleus. The goals are to 1) determine whether star
formation in
massive z~2.5 galaxies takes place in disks or is triggered
by merger
activity, 2) derive the contribution of AGNs to the
rest-frame
optical
emission, and 3) test whether the morphologies are consistent
with the
idea that the star-forming galaxies, AGNs, and
quiescent
galaxies
represent subsequent phases of an evolutionary sequence. The
combination of both
programs will provide the first morphological study
of a spectroscopically confirmed massive galaxy sample at z~2.5.
NIC2 11143
NICMOS imaging of submillimeter
galaxies with CO and PAH redshifts
We propose to obtain F110W and F160W imaging of 10 z~2.4 submillimeter
galaxies {SMGs} whose optical redshifts
have been confirmed by the
detection of
millimeter CO and/or mid- infrared PAH emission. With the
4000A break falling within/between the two imaging filters,
we will be
able to
study these sources' spatially resolved stellar populations
{modulo extinction} in the
rest-frame optical. SMGs' large luminosities
appear to be
due largely to merger-triggered starbursts; high-resolution
NICMOS imaging will help us understand the stellar masses,
mass ratios,
and other
properties of the merger progenitors, valuable information in
the effort
to model the mass assembly history of the universe.
NIC2 11155
Dust Grain Evolution in Herbig Ae Stars: NICMOS Coronagraphic Imaging
and Polarimetry
We propose to take advantage of the sensitive coronagraphic capabilities
of NICMOS
to obtain multiwavelength coronagraphic
imaging and
polarimetry of
primordial dust disks around young intermediate-mass
stars {Herbig Ae stars}, in order to
advance our understanding of how
dust grains
are assembled into larger bodies. Because the polarization
of
scattered light is strongly dependent on scattering particle size and
composition, coronagraphic imaging polarimetry
with NICMOS provides a
uniquely
powerful tool for measuring grain properties in spatially
resolved circumstellar disks. It is widely believed that planets
form
via the
gradual accretion of planetesimals in gas-rich, dusty
circumstellar disks,
but the connection between this suspected process
and the circumstellar disks that we can now observe around other
stars
remains very
uncertain. Our proposed observations, together with
powerful 3-D radiative transfer codes, will enable us to quantitatively
determine dust
grain properties as a function of location within disks,
and thus to
test whether dust grains around young stars are in fact
growing in size
during the putative planet-formation epoch. HST imaging
polarimetry of Herbig Ae stars will complement
and extend existing
polarimetric studies
of disks around lower-mass T Tauri stars and debris
disks around
older main-sequence stars. When combined with these
previous
studies, the proposed research will help us establish the
influence of
stellar mass on the growth of dust grains into larger
planetesimals, and
ultimately to planets. Our results will also let us
calibrate models
of the thermal emission from these disks, a critical
need for
validating the properties of more distant disks inferred on the
basis of
spectral information alone.
NIC3 11120
A Paschen-Alpha Study of Massive
Stars and the ISM in the Galactic
Center
The Galactic center (GC) is a unique site for a detailed
study of a
multitude of
complex astrophysical phenomena, which may be common to
nuclear regions
of many galaxies. Observable at resolutions
unapproachable in
other galaxies, the GC provides an unparalleled
opportunity to
improve our understanding of the interrelationships of
massive stars,
young stellar clusters, warm and hot ionized gases,
molecular clouds,
large scale magnetic fields, and black holes. We
propose the
first large-scale hydrogen Paschen alpha line survey
of the
GC using NICMOS on the Hubble
Space Telescope. This survey will lead to
a high
resolution and high sensitivity map of the Paschen
alpha line
emission in
addition to a map of foreground extinction, made by
comparing Paschen alpha to radio emission. This survey of the inner
75
pc of the
Galaxy will provide an unprecedented and complete search for
sites of
massive star formation. In particular, we will be able to (1)
uncover the
distribution of young massive stars in this region, (2)
locate the
surfaces of adjacent molecular clouds, (3) determine
important
physical parameters of the ionized gas, (4) identify compact
and ultra-compact
HII regions throughout the GC. When combined with
existing Chandra
and Spitzer surveys as well as a wealth of other
multi-wavelength
observations, the results will allow us to address such
questions as
where and how massive stars form, how stellar clusters are
disrupted, how
massive stars shape and heat the surrounding medium, and
how various
phases of this medium are interspersed.
WFPC2 11030
WFPC2 WF4 Temperature Reduction #3
In the fall of 2005, a serious anomaly was found in images
from the WF4
CCD in WFPC2. The WF4
CCD bias level appeared to have become unstable,
resulting in
sporadic images with either low or zero bias level. The
severity and
frequency of the problem was rapidly increasing, making it
possible that
WF4 would soon become unusable if no work-around were
found.
Examination of bias levels during periods with frequent WFPC2
images showed
low and zero bias episodes every 4 to 6 hours. This
periodicity is
driven by cycling of the WFPC2 Replacement Heater, with
the bias
anomalies occurring at the temperature peaks. The other three
CCDs {PC1,
WF2, and WF3} appear to be unaffected and continue to operate
properly.
Lowering the Replacement Heater temperature set points by a
few degrees
C effectively eliminates the WF4 anomaly. On 9 January 2006,
the upper
set point of the WFPC2 Replacement Heater was reduced from
14.9C to 12.2C. On 20
February 2006, the upper set point was reduced
from 12.2C
to 11.3C, and the lower set point was reduced from 10.9C to
10.0C. These changes restored the WF4 CCD bias level;
however, the bias
level has
begun to trend downwards again, mimicking its behavior in late
2004 and early 2005. A third
temperature reduction is planned for March
2007. We will reduce the upper set point of the heater
from 11.3C to
10.4C and the lower set point from
10.0C to 9.1C. The observations
described in this
proposal will test the performance of WFPC2 before and
after this
temperature reduction. Additional temperature reductions may
be needed
in the future, depending on the performance of WF4. Orbits:
internal 26,
external 1
WFPC2 11103
A Snapshot Survey of The Most
Massive Clusters of Galaxies
We propose the continuation of our highly successful SNAPshot survey of
a sample
of 125 very X-ray luminous clusters in the redshift
range
0.3-0.7. As demonstrated by the
25 snapshots obtained so far in Cycle14
and Cycle15
these systems frequently exhibit strong gravitational
lensing as well
as spectacular examples of violent galaxy interactions.
The proposed observations will provide important
constraints on the
cluster mass
distributions, the physical nature of galaxy-galaxy and
galaxy-gas
interactions in cluster cores, and a set of optically bright,
lensed
galaxies for further 8-10m spectroscopy. All of our primary
science goals
require only the detection and characterization of
high-surface-brightness
features and are thus achievable even at the
reduced
sensitivity of WFPC2. Because of their high redshift
and thus
compact angular
scale our target clusters are less adversely affected by
the smaller
field of view of WFPC2 than more nearby systems.
Acknowledging the broad community interest in this sample
we waive our
data rights
for these observations. Due to a clerical error at STScI
our
approved Cycle15
SNAP program was barred from execution for 3 months and
only 6
observations have been performed to date - reinstating this SNAP
at Cycle16
priority is of paramount importance to reach meaningful
statistics.
WFPC2 11122
Expanding PNe: Distances and
Hydro Models
We propose to obtain repeat narrowband images of a sample
of eighteen
planetary nebulae
{PNe} which have HST/WFPC2 archival data spanning
time
baselines of a
decade. All of these targets have previous high
signal-to-noise
WFPC2/PC observations and are sufficiently nearby to
have readily
detectable expansion signatures after a few years. Our main
scientific
objectives are {a} to determine precise distances to these
PNe based
on their angular expansions, {b} to test detailed and highly
successful
hydrodynamic models that predict nebular morphologies and
expansions for subsamples of round/elliptical and axisymmetric
PNe, and
{c} to monitor the proper motions
of nebular microstructures in an
effort to
learn more about their physical nature and formation
mechanisms. The
proposed observations will result in high-precision
distances to a
healthy subsample of PNe,
and from this their expansion
ages,
luminosities, CSPN properties, and masses of their ionized cores.
With good distances and our hydro models, we will be able
to determine
fundamental
parameters {such as nebular and central star masses,
luminosity, age}.
The same images allow us to monitor the changing
overall
ionization state and to search for the surprisingly
non-homologous growth
patterns to bright elliptical PNe of the same sort
seen by Balick & Hajian {2004} in NGC
6543. Non-uniform growth is a sure
sign of
active pressure imbalances within the nebula that require
careful hydro
models to understand.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
11202 GSAcq(1,2,1) failed to RGA Control while LOS @ 059/21:11:21z
No FGS
flags were set or 486 ESB messages received. NICMOS 705 status
buffer message (TDF down when a target acquisition SAM
request is made)
with parameter 0 and time 14666 occurred at 21:21:20z.
Post-acquisition
OBAD map at
21:19:25z had RSS error of 29.45 arcseconds.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 9 08
FGS REacq 04 04
OBAD with Maneuver
28 28
SIGNIFICANT EVENTS: (None)
-
____________________________________________________________
Lynn F. Bassford
Hubble Space Telescope
CHAMP
CHAMP Flight Operations Team Manager
Lockheed Martin
NASA GSFC PH#: 301-286-2876
"The Hubble Space
Telescope is the astronomical observatory and key to unlocking the most cosmic
mysteries of the past, present and future." - 7/26/6