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Daily Report #4574



 
 
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Old March 25th 08, 05:35 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #4574

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 images. 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)
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