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Daily Report #4459



 
 
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Old October 2nd 07, 05:25 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #4459

Notice: Due to the conversion of some ACS WFC or HRC observations into
WFPC2, or NICMOS observations after the loss of ACS CCD science capability
in January, there may be an occasional discrepancy between a proposal's
listed (and correct) instrument usage and the abstract that follows it.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4459

PERIOD COVERED: UT October 01, 2007 (DOY 274)

OBSERVATIONS SCHEDULED

WFPC2 10909

Exploring the diversity of cosmic explosions: The supernovae of gamma-ray
bursts

While the connection between gamma-ray bursts {GRBs} and supernovae {SNe} is
now clearly established, there is a large variety of observational
properties among these SNe and the physical parameters of these explosions
are poorly known. As part of a comprehensive program, we propose to use HST
in order to obtain basic information about the supernovae associated with
gamma-ray bursts. HST offers the means to cleanly separate the light curves
of the GRB afterglow from the supernova, and to remove the contamination
from the host galaxy, opening a clear route to the fundamental parameters of
the SN. From these observations, we will determine the absolute magnitude at
maximum, the shape of the spectral energy distribution, and any change over
time of the energy distribution. We will also measure the rate of decay of
the exponential tail. Merged with the ground-based data that we will obtain
for each event, we will be able to compare our data set to models and
constrain the energy of the explosion, the mass of the ejecta and the mass
of Nickel synthesized during the explosion. These results will shed light on
the apparent variety of supernovae associated with gamma-ray bursts and
X-ray flashes, and on the relation between these SNe and other, more common
varieties of core-collapse explosions.

ACS/SBC 11151

Evaluating the Role of Photoevaporation of Protoplanetary Disk Dispersal

Emission produced by accretion onto the central star leads to
photoevaporation, which may play a fundamental role in disk dispersal.
Models of disk photoevaporation by the central star are challenged by two
potential problems: the emission produced by accretion will be substantially
weaker for low-mass stars, and photoevaporation must continue as accretion
slows. Existing FUV spectra of CTTSs are biased to solar-mass stars with
high accretion rates, and are therefore insufficient to address these
problems. We propose use HST/ACS SBC PR130L to obtain FUV spectra of WTTSs
and of CTTSs at low masses and mass accretion rates to provide crucial data
to evaluate photoevaporation models. We will estimate the FUV and EUV
luminosities of low-mass CTTSs with small mass accretion rates, CTTSs with
transition disks and slowed accretion, and of magnetically-active WTTSs.

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.

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 11101

The Relevance of Mergers for Fueling AGNs: Answers from QSO Host Galaxies

The majority of QSOs are known to reside in centers of galaxies that look
like ellipticals. Numerical simulations have shown that remnants of galaxy
mergers often closely resemble elliptical galaxies. However, it is still
strongly debated whether the majority of QSO host galaxies are indeed the
result of relatively recent mergers or whether they are completely analogous
to inactive ellipticals to which nothing interesting has happened recently.
To address this question, we recently obtained deep HST ACS images for five
QSO host galaxies that were classified morphologically as ellipticals
{GO-10421}. This pilot study revealed striking signs of tidal interactions
such as ripples, tidal tails, and warped disks that were not detected in
previous studies. Our observations show that at least some "elliptical" QSO
host galaxies are the products of relatively recent merger events rather
than old galaxies formed at high redshift. However, the question remains
whether the host galaxies of classical QSOs are truly distinct from inactive
ellipticals and whether there is a connection between the merger events we
detect and the current nuclear activity. We must therefore place our results
into a larger statistical context. We are currently conducting an HST
archival study of inactive elliptical galaxies {AR-10941} to form a control
sample. We now propose to obtain deep HST/WFPC2 images of 13 QSOs whose host
galaxies are classified as normal ellipticals. Comparing the results for
both samples will help us determine whether classical QSOs reside in normal
elliptical galaxies or not. Our recent pilot study of five QSOs indicates
that we can expect exciting results and deep insights into the host galaxy
morphology also for this larger sample of QSOs. A statistically meaningful
sample will help us determine the true fraction of QSO hosts that suffered
strong tidal interactions and thus, whether a merger is indeed a requirement
to trigger nuclear activity in the most luminous AGNs. In addition to our
primary science observations with WFPC2, we will obtain NICMOS3 parallel
observations with the overall goal to select and characterize galaxy
populations at high redshifts. The imaging will be among the deepest NICMOS
images: These NICMOS images are expected to go to a limit a little over 1
magnitude brighter than HUDF-NICMOS data, but over 13 widely separated
fields, with a total area about 1.5 times larger than HUDF-NICMOS. This
separation means that the survey will tend to average out effects of cosmic
variance. The NICMOS3 images will have sufficient resolution for an initial
characterization of galaxy morphologies, which is currently one of the most
active and promising areas in approaching the problem of the formation of
the first massive galaxies. The depth and area coverage of our proposed
NICMOS observations will also allow a careful study of the mass function of
galaxies at these redshifts. This provides a large and unbiased sample,
selected in terms of stellar mass and unaffected by cosmic variance, to
study the on-going star formation activity as a function of mass {i.e.
integrated star formation} at this very important epoch.

NIC3 11107

Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation
in the Early Universe

We have used the ultraviolet all-sky imaging survey currently being
conducted by the Galaxy Evolution Explorer {GALEX} to identify for the first
time a rare population of low- redshift starbursts with properties
remarkably similar to high-redshift Lyman Break Galaxies {LBGs}. These
"compact UV luminous galaxies" {UVLGs} resemble LBGs in terms of size, SFR,
surface brightness, mass, metallicity, kinematics, dust, and color. The UVLG
sample offers the unique opportunity of investigating some very important
properties of LBGs that have remained virtually inaccessible at high
redshift: their morphology and the mechanism that drives their star
formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS in order
to 1} characterize their morphology and look for signs of interactions and
mergers, and 2} probe their star formation histories over a variety of
timescales. The images show a striking trend of small-scale mergers turning
large amounts of gas into vigorous starbursts {a process referred to as
dissipational or "wet" merging}. Here, we propose to complete our sample of
31 LBG analogs using the ACS/SBC F150LP {FUV} and WFPC2 F606W {R} filters in
order to create a statistical sample to study the mechanism that triggers
star formation in UVLGs and its implications for the nature of LBGs.
Specifically, we will 1} study the trend between galaxy merging and SFR in
UVLGs, 2} artificially redshift the FUV images to z=1-4 and compare
morphologies with those in similarly sized samples of LBGs at the same
rest-frame wavelengths in e.g. GOODS, UDF, and COSMOS, 3} determine the
presence and morphology of significant stellar mass in "pre-burst" stars,
and 4} study their immediate environment. Together with our Spitzer
{IRAC+MIPS}, GALEX, SDSS and radio data, the HST observations will form a
unique union of data that may for the first time shed light on how the
earliest major episodes of star formation in high redshift galaxies came
about. This proposal was adapted from an ACS HRC+WFC proposal to meet the
new Cycle 16 observing constraints, and can be carried out using the ACS/SBC
and WFPC2 without compromising our original science goals.

WFPC2 11023

WFPC2 CYCLE 15 Standard Darks - part 1

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 11027

Visible Earth Flats

This proposal monitors flatfield stability. This proposal obtains sequences
of Earth streak flats to construct high quality flat fields for the WFPC2
filter set. These flat fields will allow mapping of the OTA illumination
pattern and will be used in conjunction with previous internal and external
flats to generate new pipeline superflats. These Earth flats will complement
the Earth flat data obtained during cycles 4-14.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of
Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens a
window into dynamical conditions in the protoplanetary disk where they
formed as well as the history of subsequent events which sculpted the outer
Solar System and emplaced them onto their present day heliocentric orbits.
To date, at least 47 TNBs have been discovered, but only about a dozen have
had their mutual orbits and separate colors determined, frustrating their
use to investigate numerous important scientific questions. The current
shortage of data especially cripples scientific investigations requiring
statistical comparisons among the ensemble characteristics. We propose to
obtain sufficient astrometry and photometry of 23 TNBs to compute their
mutual orbits and system masses and to determine separate primary and
secondary colors, roughly tripling the sample for which this information is
known, as well as extending it to include systems of two near-equal size
bodies. To make the most efficient possible use of HST, we will use a Monte
Carlo technique to optimally schedule our observations.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports of
potential non-nominal performance that will be investigated.)

HSTARS:

11010 - REACQ(1,0,1) early loss of lock

REACQ(1,0,1) at 06:03:06 acquired fine lock at 06:08:08 but never achieved
"Sci Init", and subsequently lost fine lock at 06:21:14, TERM EXP was not
expected until 06:44:25

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL FAILURE TIMES

FGS GSacq 04 04
FGS REacq 10 09
OBAD with Maneuver 28 28

LOSS of LOCK 275/0621z

SIGNIFICANT EVENTS: (None)
 




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