HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4587
PERIOD
COVERED: UT April 10, 2008 (DOY 101)
OBSERVATIONS
SCHEDULED
NIC1/NIC2/NIC3
11318
NICMOS
Cycle 16 Multiaccum Darks
The
purpose of this proposal is to monitor the dark current, read noise,
and
shading profile for all three NICMOS detectors throughout the
duration
of Cycle 16. This proposal is a slightly modified version of
proposal
10380 of cycle 13 and 9993 of cycle12 and is the same as Cycle
15.
Covers the period from April 08 to November 08 (inclusive)
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
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.
NIC2
11208
The
co-evolution of spheroids and black holes in the last six billion
years
The
masses of giant black holes are correlated with the luminosities,
masses,
and velocity dispersions of the bulges of their host galaxies.
This
empirical correlation of phenomena on widely different scales {from
pcs
to kpcs} suggests that the formation and evolution of galaxies and
central
black holes are closely linked. In Cycle 13, we have started a
campaign
to map directly the co-evolution of spheroids and black-holes
by
measuring in observationally favorable redshift windows the empirical
correlations
connecting their properties. By focusing on Seyfert 1s,
where
the nucleus and the stars contribute comparable fractions of total
light,
black hole mass and bulge dispersion are obtained from Keck
spectroscopy.
HST is required for accurate measurement of the non
stellar
AGN continuum, the morphology of the galaxy, and the structural
parameters
of the bulge. The results at z=0.36 indicate a surprisingly
fast
evolution of bulges in the past 4 Gyrs {significant at the 95%CL},
in
the sense that bulges were significantly smaller for a given black
hole
mass. Also, the large fraction of mergers and disturbed galaxies
{4+2
out of 20} identifies gas-rich mergers as the mechanisms
responsible
for bulge-growth. Going to higher redshift -- where
evolutionary
trends should be stronger -- is needed to confirm these
tantalizing
results. We propose therefore to push our investigation to
the
next suitable redshift window z=0.57 {lookback-time 6 Gyrs}. Fifteen
objects
are the minimum number required to map the evolution of the
empirical
correlations between bulge properties and black- hole mass,
and
to achieve a conclusive detection of evolution {>99%CL}.
NIC2/NIC1/NIC3
11159
The
True Galactic Bulge Luminosity Function
We
propose to obtain second epoch imaging of the deep Galactic bulge
field
observed using NICMOS by Zoccali et al. (2000). The bulge
luminosity
and mass function suffered from 30-50% contamination by
foreground
disk stars, which was impossible to correct for in the
original
study. Revisiting the field after 9 years, we propose to
segregate
the foreground disk stars because they have large transverse
velocities,
thus revealing the luminosity function of Galactic bulge low
mass
stars to near the hydrogen burning limit. The slope of the mass
function
has implications for galaxy formation and for understanding the
nature
of microlensing in the Galactic bulge.
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.
NIC3
11149
Characterizing
the Stellar Populations in Lyman-Alpha Emitters and Lyman
Break
Galaxies at 5.7<z<7 in the Subaru Deep Field
The
epoch of reionization marks a major phase transition of the
Universe,
during which the intergalactic space became transparent to UV
photons.
Determining when this occurred and the physical processes
involved
represents the latest frontier in observational cosmology. Over
the
last few years, searches have intensified to identify the population
of
high-redshift (z>6) galaxies that might be responsible for this
process,
but the progress is hampered partly by the difficulty of
obtaining
physical information (stellar mass, age, star formation
rate/history)
for individual sources. This is because the number of z>6
galaxies
that have both secure spectroscopic redshifts and high-quality
infrared
photometry (especially with Spitzer/IRAC) is still fairly
small.
Considering that only several photometric points are available
per
source, and that many model SEDs are highly degenerate, it is
crucial
to obtain as many observational constraints as possible for each
source
to ensure the validity of SED modeling. To better understand the
physical
properties of high-redshift galaxies, we propose here to
conduct
HST/NICMOS (72 orbits) and Spitzer/IRAC (102 hours) imaging of
spectroscopically
confirmed, bright (z<26 mag (AB)) Ly-alpha emitters
(LAEs)
and Lyman-break galaxies (LBGs) at 5.7<z<7 selected from the
Subaru
Deep Field. Spectroscopic redshifts remove one critical free
parameter
from SED modeling while bright source magnitudes ensure
high-quality
photometric data. By making accurate determinations of
stellar
masses, ages, and star-formation histories, we will specifically
address
the following major questions: (1) Do LAEs and LBGs represent
physically
different galaxy populations at z>6 as suggested recently?
(2)
Is Ly-alpha emission systematically suppressed at z>6 with respect
to
continuum emission? (i.e., are we reaching the epoch of incomplete
reionization?),
and (3) Do we see any sign of abnormally young stellar
population
in any of the z>6 galaxies?
WFPC2
10841
A
Proper Motion Search for Intermediate Mass Black Holes in Globular
Clusters
{2nd Epoch Observations}
Establishing
the presence or absence of intermediate-mass black holes
{IMBH}
in globular clusters is crucial for understanding the evolution
of
dense stellar systems. Observationally, this search has been hampered
by
the low number of stars with known velocities in the central few
arcseconds.
This limits our knowledge of the velocity dispersion in the
region
where the gravitational influence of any IMBH would be felt. In
Cycle
13, we successfully obtained ACS/HRC images of the centers of five
carefully
chosen Galactic globular clusters {GO-10401} for a new proper
motion
study. Although the science case was approved and the first epoch
images
obtained, the requested future cycle observations were not
granted
{due to a general policy decision based on the strong
uncertainties
at the time concerning the immediate future of HST}. We
have
now assessed the quality of the first epoch observations. The HRC
resolution
reveals many isolated stars in to the very center of each
cluster
that remained blended or unresolved in previous WFPC2 data.
Given
a two year baseline, we are confident that we can achieve the
proper
motion precision required to place strict limits on the presence
of
an IMBH. Therefore, we request the second-epoch, follow-up
observations
to GO-10401 in order to measure the proper motions of stars
in
our target clusters. These velocity measurements will allow us to:
{i}
place constraints on the mass of a central black hole in each
cluster;
{ii} derive the internal velocity dispersion as a function of
cluster
radius; {iii} verify or reject previous reports of cluster
rotation;
and {iv} directly measure velocity anisotropy as a function of
radius.
If no second epoch data are obtained then the observing time
already
invested in the first epoch will have been wasted.
WFPC2
11201
Systemic
and Internal motions of the Magellanic Clouds: Third Epoch
Images
In
Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in
the
Magellanic Clouds centered on background quasars. We used these data
to
determine the proper motions of the LMC and SMC to better than 5% and
15%
respectively. These are by far the best determinations of the proper
motions
of these two galaxies. The results have a number of unexpected
implications
for the Milky Way-LMC-SMC system. The implied
three-dimensional
velocities are larger than previously believed, and
are
not much less than the escape velocity in a standard 10^12 solar
mass
Milky Way dark halo. Orbit calculations suggest the Clouds may not
be
bound to the Milky Way or may just be on their first passage, both of
which
would be unexpected in view of traditional interpretations of the
Magellanic
Stream. Alternatively, the Milky Way dark halo may be a
factor
of two more massive than previously believed, which would be
surprising
in view of other observational constraints. Also, the
relative
velocity between the LMC and SMC is larger than expected,
leaving
open the possibility that the Clouds may not be bound to each
other.
To further verify and refine our results we now request an epoch
of WFPC2/PC
data for the fields centered on 40 quasars that have at
least
one epoch of ACS imaging. We request execution in snapshot mode,
as
in our previous programs, to ensure the most efficient use of HST
resources.
A third epoch of data of these fields will provide crucial
information
to verify that there are no residual systematic effects in
our
previous measurements. More importantly, it will increase the time
baseline
from 2 to 5 yrs and will increase the number of fields with at
least
two epochs of data. This will reduce our uncertainties
correspondingly,
so that we can better address whether the Clouds are
indeed
bound to each other and to the Milky Way. It will also allow us
to
constrain the internal motions of various populations within the
Clouds,
and will allow us to determine a distance to the LMC using
rotational
parallax.
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
06
06
FGS
REacq
08
08
OBAD
with Maneuver
28
28
SIGNIFICANT
EVENTS: (None)