HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4674
PERIOD COVERED: 5am August 13 - 5am August 14, 2008 (DOY
226/0900z-227/0900z)
OBSERVATIONS SCHEDULED
NIC1/NIC2/NIC3 11330
NICMOS Cycle 16 Extended Dark
This takes a series of Darks in parallel to other
instruments.
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 11197
Sweeping Away the Dust: Reliable Dark Energy with an
Infrared Hubble
Diagram
We propose building a high-z Hubble Diagram using type Ia
supernovae
observed in the infrared rest-frame J-band. The infrared
has a number of
exceptional properties. The effect of dust extinction is
minimal,
reducing a major systematic that may be biasing dark
energy
measurements. Also, recent work indicates that type Ia
supernovae are
true standard candles in the infrared meaning that our
Hubble diagram
will be resistant to possible evolution in the Phillip's
relation over
cosmic time. High signal-to-noise measurements of 16 type
Ia events at
z~0.4 will be compared with an independent optical Hubble
diagram from
the ESSENCE project to test for a shift in the derived
dark energy
equation of state due to a systematic bias. In Cycle 15 we
obtained
NICMOS photometry of 8 ESSENCE supernovae and are awaiting
template
observations to place them on the IR Hubble diagram. Here
we request
another 8 supernovae be studied in the final season of the
ESSENCE
search. Because of the bright sky background, H-band
photometry of z~0.4
supernovae is not feasible from the ground. Only the
superb image
quality and dark infrared sky seen by HST makes this test
possible. This
experiment may also lead to a better, more reliable way of
mapping the
expansion history of the universe with the Joint Dark
Energy Mission.
NIC2 11799
NICMOS Non-linearity Calibration for Faint Objects
NICMOS has played a key role in probing the deep near
infrared regime
for a decade. It has been the only instrument available to
observe
objects in the near infrared that are not visible from the
ground. In
particular, it has played a major role in the SN Ia
observations at
redshifts z>1. However, the calibration of NICMOS has
turned out to be
difficult due to the apparent non-linearity of the
detectors. The NICMOS
calibration team has described the non-linearity as a
power law based on
data in the range of ~50-5000 ADU/s. The correction relies
on an
extrapolation of two orders of magnitude in flux at count
rates close to
the sky level (0.1 ADU/s) where space observations are
particularly
prized - and where SN Ia observations are made. Precise
measurements of
faint objects require us to reduce the uncertainties from
this
extrapolation. Here we propose to derive the absolute
calibration in the
sky limited regime and to characterize the non-linearity
over the entire
dynamic range for the camera/filter combination:
NIC2/F110W.
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.
WEPC2 11196
An Ultraviolet Survey of Luminous Infrared Galaxies in the
Local
Universe
At luminosities above 10^11.4 L_sun, the space density of
far-infrared
selected galaxies exceeds that of optically selected
galaxies. These
Luminous Infrared Galaxies {LIRGs} are primarily
interacting or merging
disk galaxies undergoing starbursts and creating/fueling
central AGN. We
propose far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W} UV
imaging of a
sample of 27 galaxies drawn from the complete IRAS Revised
Bright Galaxy
Sample {RBGS} LIRGs sample and known, from our Cycle 14 B
and I-band ACS
imaging observations, to have significant numbers of
bright {23 < B < 21
mag} star clusters in the central 30 arcsec. The HST UV
data will be
combined with previously obtained HST, Spitzer, and GALEX
images to {i}
calculate the ages of the clusters as function of merger
stage, {ii}
measure the amount of UV light in massive star clusters
relative to
diffuse regions of star formation, {iii} assess the
feasibility of using
the UV slope to predict the far-IR luminosity {and thus
the star
formation rate} both among and within IR-luminous
galaxies, and {iv}
provide a much needed catalog of rest- frame UV
morphologies for
comparison with rest-frame UV images of high-z LIRGs and
Lyman Break
Galaxies. These observations will achieve the resolution
required to
perform both detailed photometry of compact structures and
spatial
correlations between UV and redder wavelengths for a
physical
interpretation our IRX-Beta results. The HST UV data,
combined with the
HST ACS, Spitzer, Chandra, and GALEX observations of this
sample, will
result in the most comprehensive study of luminous starburst
galaxies to
date.
WFPC2 11122
Expanding PNe: Distances and Hydro Models
We propose to obtain repeat narrowband images of a sample
of eighteen
planetary nebulae {PNe} which have HST/WFPC2 archival data
spanning time
baselines of a decade. All of these targets have previous
high
signal-to-noise WFPC2/PC observations and are sufficiently
nearby to
have readily detectable expansion signatures after a few
years. Our main
scientific objectives are {a} to determine precise
distances to these
PNe based on their angular expansions, {b} to test
detailed and highly
successful hydrodynamic models that predict nebular
morphologies and
expansions for subsamples of round/elliptical and
axisymmetric PNe, and
{c} to monitor the proper motions of nebular microstructures
in an
effort to learn more about their physical nature and
formation
mechanisms. The proposed observations will result in
high-precision
distances to a healthy subsample of PNe, and from this
their expansion
ages, luminosities, CSPN properties, and masses of their
ionized cores.
With good distances and our hydro models, we will be able
to determine
fundamental parameters {such as nebular and central star
masses,
luminosity, age}. The same images allow us to monitor the
changing
overall ionization state and to search for the
surprisingly
non-homologous growth patterns to bright elliptical PNe of
the same sort
seen by Balick & Hajian {2004} in NGC 6543.
Non-uniform growth is a sure
sign of active pressure imbalances within the nebula that
require
careful hydro models to understand.
WFPC2 11177
The Nature of z=3 Lyman-Alpha Emitters
The advent of large mosaic CCD cameras on 4 -- 8 m class
telescopes has
recently led to a revolution in our ability to detect
primordial
galaxies. Today, large numbers of strong Ly-alpha emitters
(LAEs) are
being discovered between 2.4 < z < 6. These are
important objects: not
only do they sample a part of the galaxy luminosity
function that is
inaccessible to the Lyman-break technique, but they also
tend to be
younger and less chemically evolved. In fact, the LAEs now
being found
are currently our best candidates for galaxies in the act
of formation.
To investigate the properties of this class of objects, we
have
conducted an extremely deep narrow-band (5000 Angstrom;
FWHM = 50
Angstrom) and broad-band (UBVRIzJK) survey of the Extended
Chandra Deep
Field South, and have identified a homogeneous sample of
strong Ly-
alpha emitters at z = 3.11. Twenty-seven of these objects
are located
within the region surveyed by Great Observatories Origins
Deep Survey
(GOODS) and have detailed morphological information
available from the
rest-frame ultraviolet. We propose 0.2" resolution
narrow-band imaging
of 11 of our LAEs using the F502N filter of WFPC2. By
comparing the
Ly-alpha and rest-frame UV continuum morphologies of these
galaxies, we
will be able to look for the presence of outflows,
constrain their dust
content, and test whether these objects are truly
primordial galaxies.
WFPC2 11227
The Orbital Period for an Ultraluminous X-ray Source in
NGC1313
The ultraluminous X-ray sources {ULXs} are extragalactic
point sources
with luminosities that exceed the Eddington luminosity for
conventional
stellar-mass black holes by factors of 10 - 100. It has
been hotly
debated whether the ULXs are just common stellar-mass
black hole sources
with beamed emission or whether they are sub-Eddington
sources that are
powered by the long-sought intermediate mass black holes
{IMBH}. To
firmly decide this question, one must obtain dynamical
mass measurements
through photometric and spectroscopic monitoring of the
secondaries of
these system. The crucial first step is to establish the
orbital period
of a ULX, and arguably the best way to achieve this goal
is by
monitoring its ellipsoidal light curve. The extreme ULX
NGC1313 X-2
provides an outstanding target for an orbital period
determination
because its relatively bright optical counterpart {V =
23.5} showed a
15% variation between two HST observations separated by
three months.
This level of variability is consistent with that expected
for a tidally
distorted secondary star. Here we propose a set of 20
imaging
observations with HST/WFPC2 to define the orbital period.
This would be
the first photometric measurement of the orbital period of
a ULX binary.
Subsequently, we will propose to obtain spectroscopic
observations to
obtain its radial velocity amplitude and thereby a
dynamical estimate of
its mass.
WFPC2 11336
X-ray and UV Photo-ionization and Photo-excitation of
Pre-main-sequence Star
Transitional Disks
Transitional disks are one of the most crucial and
important stages of
the evolution of pre-main-sequence stars and
protoplanetary systems.
These disks have transformed most of the dust and gas in
their inner
regions into planetesimals and show clear inner ``holes''
that almost
certainly harbor infant planetary systems. We propose to
observe 3 young
stars with transitional disks (T Cha, GM Aur, LkHa 330)
using ACIS-S to
measure their X-ray radiation field and coronal emission
properties and
HST ACS- SBC to image the fluorescently excited molecular
hydrogen in
these systems to determine if the gas distribution follows
the behavior
seen in the dust distribution. [Only observations of GM
Aur were
approved. ]Our broader goal is to model the X-ray/UV
photoionization and
photoexcitation of the disks and study their
photochemistry.
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 08 08
FGS REacq 07 07
OBAD with Maneuver 30 30
SIGNIFICANT EVENTS: (None)