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 # 4408
PERIOD COVERED: UT July 19, 2007 (DOY 200)
OBSERVATIONS SCHEDULED
ACS/SBC 10907
New Sightlines for the Study of Intergalactic Helium: A
Dozen
High-Confidence, UV-Bright Quasars from SDSS/GALEX
The reionization of intergalactic helium is thought to
have occurred
between redshifts of about 3 and 4. Detailed study of HeII
Lyman-alpha
absorption toward a handful quasars at 2.7<z<3.3
demonstrates the great
potential of such probes of the IGM, but the current
critically-small
sample limits confidence in resulting cosmological
inferences. The
requisite unobscured quasar sightlines to high-redshift
are extremely
rare, especially due to severe absorption in random
intervening
Lyman-limit systems, but SDSS provides thousands of
z>3.1 quasars
potentially suitable for HeII studies. We have
cross-correlated SDSS
quasars with GALEX UV sources to obtain a dozen new, very
high-confidence, candidate quasars/sightlines {z=3.1 to
4.1} potentially
useful for detailed HeII studies even with current HST
instruments. We
propose brief, 2-orbit per target, reconnaissance spectral
exposures
with the ACS SBC prism to definitively verify UV flux down
to the HeII
break. Our combined SDSS/GALEX selection insures a very
high- yield of
confirmations, as the quasars are already known to be
UV-bright from
broadband GALEX images. The additional sightlines,
extending to very
high-redshift, will directly enable ensemble spectral
stacks, as well as
long exposure follow-up spectra, at high S/N with the
ACS/SBC
ultraviolet prisms {or perhaps STIS or
measure the spectrum and evolution of the ionizing background
radiation,
the evolution of HeII opacity, and the density of
intergalactic baryons.
ACS/WFC/WFPC2 10904
Star formation in extended UV disk {XUV-disk} galaxies
The Galaxy Evolution Explorer {GALEX} has discovered the
existence of
extended UV-disk {XUV-disk} galaxies. This class of
intriguing spiral
galaxies is distinguished by UV-bright regions of star
formation located
at extreme galactocentric radii, commonly reaching many
times the
optical extent of each target. XUV-disks represent a
population of
late-type galaxies still actively building, or
significantly augmenting,
their stellar disk in the outer, low-density environment.
Prior to
GALEX, such regions were considered to be far more stable
against star
formation than now realized. Our work on these targets has
led to the
recognition of the XUV phenomenon as probing a diverse
population of
galaxies which, although having certain commonality in
terms of their
present XUV star formation, have apparently experienced
different star
formation histories {as judged by their outer disk
UV-optical colors and
morphology}. In ordinary spirals, disk formation occurred
at a much
earlier epoch, making today's XUV-disks useful templates
for
commonplace, high z galaxies. The diverse XUV-disks in our
sample may
represent snapshots of different phases in the disk
building process. We
seek to characterize the demographics of star forming
regions occupying
this environmental range, especially in contrast to their
inner disk
counterparts. HST imaging is needed to accurately
characterize the
massive stars and clusters which have, in fact, managed to
form. The
GALEX observations are limited by 5" resolution. Deep
ACS FUV, B, V, I,
and H-alpha imaging {along with parallel WFPC2 data} will
allow: {1}
photometric classification of the
the cluster mass function and age distribution, {3}
critical accounting
for possible leakage of Lyman continuum photons in a
porous ISM or an
IMF change, and {4} population synthesis modeling of the
field SFH on
Gyr timescales. We benefit from extensive archival HST
observations of
our target galaxies, although the outer disk has yet to be
probed.
NIC1/NIC2/NIC3 8794
NICMOS Post-SAA calibration - CR Persistence Part 5
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.
NIC2 10893
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 Phillips relation
over cosmic
time. High signal-to-noise measurements of 9 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. 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
WFPC2 10818
Very Young Globular Clusters in M31 ?
We propose to use HST's unique high spatial resolution
imaging
capabilities to conclusively confirm or refute the
presence of alleged
very young globular clusters in M31. Such young globular
clusters with
ages < 3 Gyr are not present in our galaxy, and, if
real, would lead to
a striking difference in the age distribution of the GCs
between M31 and
the
in M31 is confirmed through our proposed ACS imaging {now
WFPC2 imaging}
with HST, this would suggest major differences in the
history of
assembly of the two galaxies, with probable substantial
late accretion
into M31 which did not occur in our own galaxy.
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
optimally schedule our observations.
WFPC2 11202
The Structure of Early-type Galaxies: 0.1-100 Effective
Radii
The structure, formation and evolution of early-type
galaxies is still
largely an open problem in cosmology: how does the
Universe evolve from
large linear scales dominated by dark matter to the highly
non-linear
scales of galaxies, where baryons and dark matter both
play important,
interacting, roles? To understand the complex physical
processes
involved in their formation scenario, and why they have
the tight
scaling relations that we observe today {e.g. the
Fundamental Plane}, it
is critically important not only to understand their
stellar structure,
but also their dark-matter distribution from the smallest
to the largest
scales. Over the last three years the SLACS collaboration
has developed
a toolbox to tackle these issues in a unique and
encompassing way by
combining new non-parametric strong lensing techniques,
stellar
dynamics, and most recently weak gravitational lensing,
with
high-quality Hubble Space Telescope imaging and VLT/Keck
spectroscopic
data of early-type lens systems. This allows us to break
degeneracies
that are inherent to each of these techniques separately
and probe the
mass structure of early-type galaxies from 0.1 to 100
effective radii.
The large dynamic range to which lensing is sensitive
allows us both to
probe the clumpy substructure of these galaxies, as well
as their
low-density outer haloes. These methods have convincingly
been
demonstrated, by our team, using smaller pilot-samples of
SLACS lens
systems with HST data. In this proposal, we request
observing time with
WFPC2 and NICMOS to observe 53 strong lens systems from
SLACS, to obtain
complete multi-color imaging for each system. This would
bring the total
number of SLACS lens systems to 87 with completed HST
imaging and
effectively doubles the known number of galaxy-scale
strong lenses. The
deep HST images enable us to fully exploit our new
techniques, beat down
low-number statistics, and probe the structure and
evolution of early-
type galaxies, not only with a uniform data-set an order
of magnitude
larger than what is available now, but also with a fully
coherent and
self-consistent methodological approach!
WFPC2 11218
Snapshot Survey for Planetary Nebulae in Globular Clusters
of the Local
Group
Planetary nebulae {PNe} in globular clusters {GCs} raise a
number of
interesting issues related to stellar and galactic evolution.
The number
of PNe known in Milky Way GCs, 4, is surprisingly low if
one assumes
that all stars pass through a PN stage. However, it is
likely that the
remnants of stars now evolving in Galactic GCs leave the
AGB so slowly
that any ejected nebula dissipates long before the star
becomes hot
enough to ionize it. Thus there should not be ANY PNe in
Milky Way
GCs--but there are four! It has been suggested that these
PNe are the
result of mergers of binary stars within GCs, i.e., that
they are
descendants of blue stragglers. The frequency of
occurrence of PNe in
external galaxies poses more questions, because it shows a
range of
almost an order of magnitude. I propose a Snapshot survey
aimed at
discovering PNe in the GC systems of Local Group galaxies
more distant
than the Magellanic Clouds. These clusters, some of which
may be much
younger than their counterparts in the Milky Way, might
contain many
more PNe than those of our own galaxy. I will use the
standard technique
of emission-line and continuum imaging, which easily
discloses PNe.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
#10901 MNDRDT1 & MNDRDT2 out of limits for 1 minute.
At 200/15:03:03 the mnemonics MNDRDT1 & MNDRDT2 (NCS
CPL RES-RAD B DELTA
T) flagged out of limits - red low at 5.3725 & 6.46859
respectively.
They returned back in bounds at 200/15:04:02. the red
lower limit is set
at 7.0.
#10902 OBAD Failed Identification (ESB 1902), GSAcq not
attempted.
At 200/15:33:26z "OBAD failed". The second OBAD
failed during LOS
scheduled 15:33:38-15;46;00z. Other data included:
Mnemonic GOBSTAT =
255, GCHACL09 = 1, TGS Mode = T2G.
GSAcq (1,3,1) scheduled from 15:43:55-15:50:59 was not
attempted.
OBAD #1: V1 5.77, V2 -3.06, V3 -9.55, RSS 11.57
OBAD #2: V1 -33466.27, V2 -13497.54, V3 24133.27, RSS
43411.86
OBAD MAP: V1 -131.31, V2 131.93, V3 -105.57, RSS 213.99
REAcq (1,3,1) scheduled for 17:21:35-17:28:56 failed. No
data available
due to LOS.
#10903 GSACQ(1,3,1) failed.
GSACQ(1,3,1) at 200/20:36:06 failed to RGA control. No FGS
flags were
seen. Vehicle was LOS at time of failure. At acquisition
of signal
vehicle had OBAD RSS error of 11020.84 arcseconds.
COMPLETED OPS REQUEST: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
08
06
FGS
REacq
07
06
OBAD with Maneuver
30
27
COMPLETED OPS NOTES: (None)
SIGNIFICANT EVENTS: (None)