HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4574
PERIOD
COVERED: UT March 24, 2008 (DOY 084)
OBSERVATIONS
SCHEDULED
WFPC2
11024
WFPC2
CYCLE 15 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.
FGS
11210
The
Architecture of Exoplanetary Systems
Are
all planetary systems coplanar? Concordance cosmogony makes that
prediction.
It is, however, a prediction of extrasolar planetary system
architecture
as yet untested by direct observation for main sequence
stars
other than the Sun. To provide such a test, we propose to carry
out
FGS astrometric studies on four stars hosting seven companions. Our
understanding
of the planet formation process will grow as we match not
only
system architecture, but formed planet mass and true distance from
the
primary with host star characteristics for a wide variety of host
stars
and exoplanet masses. We propose that a series of FGS astrometric
observations
with demonstrated 1 millisecond of arc per-observation
precision
can establish the degree of coplanarity and component true
masses
for four extrasolar systems: HD 202206 {brown dwarf+planet}; HD
128311
{planet+planet}, HD 160691 = mu Arae {planet+planet}, and HD
222404AB
= gamma Cephei {planet+star}. In each case the companion is
identified
as such by assuming that the minimum mass is the actual mass.
For
the last target, a known stellar binary system, the companion orbit
is
stable only if coplanar with the AB binary orbit.
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.
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
11147
The
Origin of Diffuse UV Light from Spiral Disks
The
ultraviolet light from galaxies has been used as a beacon for
tracing
the cosmic star formation history of the Universe, yet we have
an
incomplete understanding of many characteristics of this light. Most
of
the UV emission from nearby, normal star--forming galaxies is
unresolved
and "diffuse", and GALEX has shown that in spiral disks it
permeates
the inter-arm regions. The nature of this diffuse inter- arm
component
is under debate. Recent results suggest that it may arise from
non-
ionizing UV photons which originate in star forming regions in the
spiral
arms, travel in the plane of the galaxy, and then scatter off of
diffusely
distributed cold dust grains. Alternatively, an in-situ,
unresolved
stellar population could produce the observed inter-arm UV
emission.
This project seeks to establish which of the two competing
scenarios
is responsible for the bulk of this diffuse emission. We
propose
to use HST's UV imaging capability (ACS/SBC) to obtain deep
observations
of selected fields in the nearby spiral galaxy M101, for
which
available (low angular resolution) data favor the 'scattered
light'
scenario. Our observations are designed to detect any faint,
UV-luminous
stellar population down to main sequence B5 stars. With
these
data, we will establish the nature of the bulk of the diffuse UV
light
in this spiral galaxy by: (i) quantifying the contribution from
dust-scattered
light; (ii) measuring the contribution to the ubiquitous
diffuse
ionized medium from in- situ ionizing stars; and (iii) providing
constraints
on the observed stellar mass function in the field. Only HST
has
the UV sensitivity and angular resolution to discriminate in-situ
stellar
populations from scattered light. The ultimate goal of this
project
is to re-'calibrate' the UV emission as a star formation rate
indicator,
which will need to account for any scattered component.
WFPC2
11070
WFPC2
CYCLE 15 Standard Darks - part II
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
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
11169
Collisions
in the Kuiper belt
For
most of the 15 year history of observations of Kuiper belt objects,
it has
been speculated that impacts must have played a major role in
shaping
the physical and chemical characteristics of these objects, yet
little
direct evidence of the effects of such impacts has been seen. The
past
18 months, however, have seen an explosion of major new discoveries
giving
some of the first insights into the influence of this critical
process.
From a diversity of observations we have been led to the
hypotheses
that: {1} satellite-forming impacts must have been common in
the
Kuiper belt; {2} such impacts led to significant chemical
modification;
and {3} the outcomes of these impacts are sufficiently
predictable
that we can now find and study these impact-derived systems
by
the chemical and physical attributes of both the satellites and the
primaries.
If our picture is correct, we now have in hand for the first
time
a set of incredibly powerful tools to study the frequency and
outcome
of collisions in the outer solar system. Here we propose three
linked
projects that would answer questions critical to the multiple
prongs
of our hypothesis. In these projects we will study the chemical
effects
of collisions through spectrophotometric observations of
collisionally
formed satellites and through the search for additional
satellites
around primaries with potential impact signatures, and we
will
study the physical effects of impacts through the examination of
tidal
evolution in proposed impact systems. The intensive HST program
that
we propose here will allow us to fully test our new hypotheses and
will
provide the ability to obtain the first extensive insights into
outer
solar system impact processes.
WFPC2
11182
The
Mass of the Milky Way: Orbits for Leo I and Leo II: Second Epoch
Imaging
of Leo II
Constraining
the mass of the Galaxy at large radii remains a difficult
problem.
Available data are still rather scarce, and orbits of even a
few
objects at large radii can have a large impact. We propose to obtain
proper
motions for the two satellites Leo I and Leo II, which orbit the
Galaxy
at about 200 kpc. Together with the radial velocities of these
galaxies,
which are well known, the proper motions allow space
velocities
to be constructed: these can remove significant uncertainty
in
the Galactic mass models, and in particular settle the vexed question
of
whether or not Leo I is gravitationally bound to the Galaxy. The
proper
motion of Leo I is addressed in a companion archival proposal;
here
we address the WFPC2 imagery of Leo II.
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
15
15
FGS
REacq
00
00
OBAD
with Maneuver 30
30
SIGNIFICANT
EVENTS: (None)