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Daily Report # 4332



 
 
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Old April 3rd 07, 04:16 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report # 4332

Notice: For the foreseeable future, the daily reports may contain apparent
discrepancies between some proposal descriptions and the listed instrument
usage. This is due to the conversion of previously approved ACS WFC or HRC
observations into WFPC2, or NICMOS observations subsequent to the loss of
ACS CCD science capability in late January.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4332

PERIOD COVERED: UT April 03, 2007 (DOY 092)

OBSERVATIONS SCHEDULED

WFPC2 10880

The host galaxies of QSO2s: AGN feeding and evolution at high luminosities

Now that the presence of supermassive black holes in the nuclei of galaxies
is a well established fact, other questions related to the AGN phenomena
still have to be answered. Problems of particular interest are how the AGN
gets fed, how the black hole evolves and how the evolution of the black hole
is related to the evolution of the galaxy bulge. Here we propose to address
some of these issues using ACS/WFC + F775W snapshot images of 73 QSO2s with
redshifts in the range 0.3z0.4. These observations will be combined with
similar archival data of QSO1s and ground based data of Seyfert and normal
galaxies. First, we will intestigate whether interactions are the most
important feeding mechanism in high luminosity AGNs. This will be done in a
quantitative way, comparing the asymmetry indices of QSO2 hosts with those
of lower luminosity AGNs and normal galaxies. Second, we will do a detailed
study of the morphology of the host galaxies of both QSO types, to determine
if they are similar, or if there is an evolutionary trend from QSO2s to
QSO1s. The results from this project will represent an important step in the
understanding of AGN evolution, and may also introduce a substantial
modification to the Unified Model.

WFPC2 10917

Afterglows and Environments of Short-Hard Gamma-Ray Bursts

Discovery of the first afterglows of short-hard bursts {SHBs} has led to a
revolution in our understanding of these events, strongly suggesting that
they originate in the mergers of compact-object binaries. Capitalizing on
this progress, we propose to pursue the next generation of SHB observations
with HST, tracking the decay of all accessible SHB afterglows to late times
and pinpointing the location of several more within the context of their
host galaxies. These observations will allow quantitative analysis of
progenitor lifetimes and short burst environments, enable direct
confrontation with population synthesis models, and provide updated event
rate estimates for the LIGO and VIRGO gravitational-wave detectors that are
now coming on-line.

FGS 10612

Binary Stars in Cyg OB2: Relics of Massive Star Formation in a Super-Star
Cluster

We propose to make a high angular resolution SNAP survey of the massive
stars in the nearby, super-star cluster Cyg OB2. We will use FGS1r TRANS
mode observations to search for astrometric companions in the separation
range of 0.01 to 1.00 arcsec and in the magnitude difference range smaller
than 4 magnitudes. The observations will test the idea that the formation of
very massive stars involves mergers and the presence of nearby companions.
Discovery of companions to massive stars in this relatively nearby complex
will provide guidance in the interpretation of apparently supermassive stars
in distant locations. The search for companions will also be important for
verification of fundamental parameters derived from spectroscopy,
adjustments to main sequence fitting and distance estimations, determining
third light contributions of eclipsing binaries, identifying wide colliding
wind binaries, studying the relationship between orbital and spin angular
momentum, and discovering binaries amenable to future mass determinations.
The massive star environment in Cyg OB2 may be similar to the kinds found in
the earliest epoch of star formation, so that a study of the role of
binaries in Cyg OB2 will help us understand the formation processes of the
first stars in the Universe.

NIC1 10859

Precise Measurements of Sgr A* Flare Activity

Correlated X-ray and near-IR flare emission from Sgr A*, the closest
supermassive black hole, contains information about the hydrodynamics,
energetics, and accretion behavior of matter within the innermost ten
Schwarzschild radii of the hole. We propose HST/NICMOS observations of
near-IR flares, in conjunction with already approved obsrevations using
XMM-Newton {214 ksec} and CSO {3 nights}, which can make the precise, new
measurements necessary to understand the radiation mechanism and low
luminosity of Sgr A*. HST/NICMOS is required due to its very low and stable
background, and its stable, tightly focused PSF, which allow accurate
measurement of fainter flares than can be observed using groundbased
adaptive optics systems. We will measure the spectral index distribution,
the time-averaged flux and duration of flares, and the statistics of flare
activity, and will confirm previously reported quasi-periodic variability.
These measurements will have far-reaching implications for testing the
inverse Compton scattering {ICS} and synchrotron models of low-luminosity
flares, for understanding the process of accretion onto and outflow from
supermassive black holes, and for constraining the acceleration mechanism of
flares and the inferred black hole spin. This knowledge, in turn, will help
us understand more generally low-luminosity AGN and X-ray binaries in a very
low/quiescent accretion state.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

A new proceedure proposed to alleviate the CR-persistence problem of NICMOS.
Dark frames will be obtained immediately upon exiting the SAA contour 23,
and everytime 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.

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 11083

The Structure, Formation and Evolution of Galactic Cores and Nuclei

A surprising result has emerged from the ACS Virgo Cluster Survey {ACSVCS},
a program to obtain ACS/WFC gz imaging for a large, unbiased sample of 100
early-type galaxies in the Virgo Cluster. On subarcsecond scales {i.e.,
0.1"-1"}, the HST brightness profiles vary systematically from the
brightest giants {which have nearly constant surface brightness cores} to
the faintest dwarfs {which have compact stellar nuclei}. Remarkably, the
fraction of galaxy mass contributed by the nuclei in the faint galaxies is
identical to that contributed by supermassive black holes in the bright
galaxies {0.2%}. These findings strongly suggest that a single mechanism is
responsible for both types of Central Massive Object: most likely internally
or externally modulated gas inflows that feed central black holes or lead to
the formation of "nuclear star clusters". Understanding the history of gas
accretion, star formation and chemical enrichment on subarcsecond scales has
thus emerged as the single most pressing question in the study of nearby
galactic nuclei, either active or quiescent. We propose an ambitious HST
program {199 orbits} that constitutes the next, obvious step forward:
high-resolution, ultraviolet {WFPC2/F255W} and infrared {NIC1/F160W} imaging
for the complete ACSVCS sample. By capitalizing on HST's unique ability to
provide high-resolution images with a sharp and stable PSF at UV and IR
wavelengths, we will leverage the existing optical HST data to obtain the
most complete picture currently possible for the history of star formation
and chemical enrichment on these small scales. Equally important, this
program will lead to a significant improvement in the measured structural
parameters and density distributions for the stellar nuclei and the
underlying galaxies, and provide a sensitive measure of "frosting" by young
stars in the galaxy cores. By virtue of its superb image quality and stable
PSF, NICMOS is the sole instrument capable of the IR observations proposed
here. In the case of the WFPC2 observations, high-resolution UV imaging {
0.1"} is a capability unique to HST, yet one that could be lost at any any
time.

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 09 09
FGS REacq 05 05
OBAD with Maneuver 26 26

SIGNIFICANT EVENTS: (None)
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