Status Report

NASA Hubble Space Telescope Daily Report # 3533

By SpaceRef Editor
January 20, 2004
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




NIC1/NIC2/NIC3 9993

Cycle 12 NICMOS dark current, shading profile, and read noise monitoring

The purpose of this proposal is to monitor the dark current, read noise, and
shading profile for all three NICMOS detectors throughout the duration of Cycle
12. This proposal is an essentially unchanged continuation of PID 9636 which
cover the duration of Cycle 11.

ACS 9984

Cosmic Shear With ACS Pure Parallels

Small distortions in the shapes of background galaxies by foreground mass
provide a powerful method of directly measuring the amount and distribution of
dark matter. Several groups have recently detected this weak lensing by
large-scale structure, also called cosmic shear. The high resolution and
sensitivity of HST/ACS provide a unique opportunity to measure cosmic shear
accurately on small scales. Using 260 parallel orbits in Sloan textiti {F775W}
we will measure for the first time: beginlistosetlength sep0cm
setlength opsep0cm em the cosmic shear variance on scales <0.7 arcmin, em the
skewness of the shear distribution, and em the magnification effect.
endlist Our
measurements will determine the amplitude of the mass power spectrum
sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20, and the mass density
Omega_m with s/n=4. They will be done at small angular scales where non-linear
effects dominate the power spectrum, providing a test of the gravitational
instability paradigm for structure formation. Measurements on these scales are
not possible from the ground, because of the systematic effects induced by PSF
smearing from seeing. Having many independent lines of sight reduces the
uncertainty due to cosmic variance, making parallel observations ideal.


Hubble Heritage Observations of Ring Galaxy AM0644-741

Ring galaxies are an aesthetically captivating galactic/inter-galactic
phenomenon which HST is exceptionally qualified to observe. AM0644-741, the
Lindsay-Shapley ring galaxy, will be observed as part of the Hubble Heritage
Project. The Cartwheel galaxy {AM0035-335} is similar in shape and
morphology to
AM0644-741, but the Cartwheel’s ring has a smaller angular scale on the sky and
is about 50% further away. With a larger apparent size not completely
in a single WFPC2 pointing, about 30% better absolute spatial resolution should
be achievable with AM0644-741 compared with the Cartwheel. AM0644-741 and two
companion galaxies {including a candidate impactor} fits within a single rough
ACS pointing. The ring itself represents a relatively brief but important
transient evolutionary stage in only a small fraction of galaxies in the
universe. It is believed that rings such as found in AM0035-335 and AM0644-741
are likely produced after a collision between two or more galaxies with a
relatively narrow range of encounter velocities, relative masses, and impact
parameters. If the encounter is outside of this parameter space, other unique
tidal features can be produced, such as tails and mergers. The Cartwheel and
AM0644-741 are at roughly similar evolutionary stages. But rings are not
uniquely formed from collisions of the type producing the Cartwheel. For
example, Hoag’s Object represents an apparent ring galaxy likely formed by a
different mechanism: complete tidal disruption of a closely orbiting small
galaxy around a giant elliptical. In the case of the Cartwheel and the southern
ring galaxy AM0644-741, the rings are not entire disrupted galaxies, but
probably material from within one of the galaxies which traces the result of a
pass-through collision of an intruder galaxy. Indeed, both objects have nearby
collision candidates. After passage of the intruder, the remanant velocity of
the material is sufficient to continue expansion after closest approach shortly
following pass-through, thereby forming a coherent, expanding ring structure.
Local conditions in the ring are not the same as before the encounter, so gas
and dust resident in the ring can collapse to produce starbursts. If AM0644-741
is so similar to the Cartwheel, then why image it with HST? The aim of the
Heritage Project is to provide spectacular HST color images for public release,
outreach, and education. AM0644-741 is nearly ideally sized to fit into the
ACS/WFC. The Cycle 4 GO 5410 Cartwheel { } program with WFPC2 was a
3-orbit observation set in only two colors: B {3200 seconds} & I {1800
Nevertheless, that composite picture has had enduring, wide appeal with the
public, and has provided an aesthetic benchmark motivating this target
selection. Five orbits in B, V, R, and I with ACS/WFC are to be used to produce
a higher signal-to-noise product and provide richer color information at the
high angular resolution inherent with HST.


A test of the foreground proximity effect at z=1.2

The diffuse UV background flux J is a crucial component for cosmological
evolution models, though few determinations have been made. The prox- imity
effect, the thinning out of the Lyman alpha forest near a sight- line’s
background quasar and explained at least partly by the enhanced ionization from
the quasar, is a key method to measure J. A foreground proximity effect {FPE}
should exist from quasars close on the sky but at different z; it can constrain
J and test the enhanced ionization model. Galaxy clustering around the quasar
may modify the effect, but knowing the galaxy density around the Lya forest
should allow for corrections. We propose to measure the FPE at z=1.2, which is
advantageous because 1} the diffuse UV flux is lower, and thus contrast
with the
UV flux of neighboring quasars is higher, and 2} galaxies are easier to
at z=1.2. We have good knowledge of the physical volume we wish to study
surveys for quasars, MgII absorbers and galaxies, to constrain the
redshift-dependent galaxy density along the line of sight. We will analyze the
results based on pixel opacities, which is more sensitive to fluctuations in J
than traditional line counting, and will compare our results with cosmological
simulations to derive estimates of the UV background in the context of
physical models.

NIC/NIC3 9865

The NICMOS Parallel Observing Program

We propose to continue managing the NICMOS pure parallel program. Based on our
experience, we are well prepared to make optimal use of the parallel
opportunities. The improved sensitivity and efficiency of our observations will
substantially increase the number of line-emitting galaxies detected. As our
previous work has demonstrated, the most frequently detected line is Halpha at
0.7<z<1.9, which provides an excellent measure of current star formation rate.
We will also detect star-forming and active galaxies in other redshift ranges
using other emission lines. The grism observations will produce by far the best
available Halpha luminosity functions over the crucial–but poorly
observed–redshift range where galaxies appear to have assembled most of their
stellar mass. This key process of galaxy evolution needs to be studied with IR
data; we found that observations at shorter wavelengths appear to have missed a
large fraction of the star-formation in galaxies, due to dust reddening. We
also obtain deep F110W and F160W images, to examine the space densities and
morphologies of faint red galaxies. In addition to carrying out the public
parallels, we will make the fully reduced and calibrated images and spectra
available on-line, with some ground-based data for the deepest parallel fields

ACS/WFC 9860

ESSENCE: Measuring the Dark Energy Equation of State

The accelerating universe appears to be dominated by a dark energy with a
significant negative pressure. The ratio of the pressure to density of this
mysterious energy {its equation of state} is an observable which can
differentiate between the proliferating candidate theories. We propose to
estimate the dark energy equation of state by observing Type Ia supernovae at
redshifts near z=0.7 with HST in concert with the on-going ESSENCE NOAO Survey
program that is discovering and studying supernovae between 0.3<z<0.8. We show
that an interesting constraint on the equation of state can be made with
supernovae observed at modest redshifts given the current knowledge of the
matter density. We will follow 10 Type Ia supernovae discovered from the ground
and passed to HST without disrupting its schedule. The full data set will
constrain the equation of state to 10% and strictly limit the range of possible
dark energy models. In keeping with the ESSENCE policy, these observations will
available to the community immediately.

NIC3 9846

The Origins of Sub-stellar Masses: Searching for the End of the IMF

Is there a preferred scale that defines the end of the IMF? We propose to test
this hypothesis by conducting a deep spectroscopic survey of extremely low mass
objects in the embedded young cluster associated with NGC1333. At a distance of
only 300pc, this cluster is one of the nearest examples of a dense young
cluster. We will be able to obtain R=200 spectra and photometry for 40-60
cluster members with masses between 5-40 Jupiter masses at an age of 1 Myr
observed through A{v}<10 mag. This will enable us to estimate temperatures and
luminosities for all sources detected in the survey. We will compare their
positions in an H-R diagram to PMS evolutionary tracks in order to estimate
their ages and masses. For a solar metallicity cloud at a temperature of 10 K,
the minimum mass for fragmentation is thought to be 10 Jupiter masses. A
statistically significant sample of objects detected below this limit would
challenge the role of hierarchical fragmentation in limiting substellar masses.
The proximity of this cluster combined with the unique sensitivity, wavelength
coverage, and multi-object spectroscopic capability of NICMOS on HST make this
experiment possible.


An ACS/WFC H-alpha Survey of the Orion Nebula

We propose to survey nearly 500 square arcminutes of the Orion Nebula in
using the ACS/WFC, increasing the sky coverage by an order of magnitude
over the
sum of all previous HST observations. This survey will, for the first time,
sample the majority of young stars and circumstellar environments in the
extended Trapezium cluster of 2, 000 low-mass stars. Our primary goal is to
determine the survival rate and statistical properties of protoplanetary disks
in the type of radiation field and dynamical environment in which most
stars are
born. The survey will be used to search for new silhouette disks, bright
proplyds, microjets, large-scale outflows, and to characterize the
properties of
these objects as a function of location in the nebula. We will determine
accurate proper motions in regions where previous HST data exist. However, 90%
of our fields will be observed with HST for the first time. This survey will
provide the first complete census of pre-main sequence objects and outflows in
an HII region and will constrain the extent of hazards to planet formation in
such environments. The images will also provide a legacy for future stellar and
nebular variability studies and proper motion measurements by providing a first
epoch data base.


Accurate and Robust Calibration of the Extragalactic Distance Scale with the
Maser Galaxy NGC4258

The extragalactic distance scale {EDS} is defined by a comparison of Cepheid
Period-Luminosity {PL} relations for nearby galaxies and the LMC, whose
uncertain distance is thereby the SOLE anchor. Studies of maser sources
the central black hole in the galaxy NGC4258 have provided the most accurate
extragalactic distance ever {7.2+/- 0.5Mpc}. Since this distance is well
determined and based on GEOMETRIC arguments, NGC4258 can provide a much needed
new anchor for the EDS. We propose multi-epoch BVIH observations of NGC4258 in
order to discover about 100 Cepheids and to characterize their light curves
2-3 times greater accuracy than was previously possible with WFPC2. At 90
{48 in Cycle 12; 42 in Cycle 13}, this is a relatively large program. However,
the result will have a major impact on the EDS, and substantial attention must
be paid to characterization and minimization of systematic errors, as from
metallicity, crowding, and blending. The resulting dataset will be the most
complete for Cepheids in any galaxy yet studied with HST. In an ongoing
NASA-funded program {OSS-SARA}, we are using new analysis techniques and radio
data to reduce uncertainty in the geometric distance to < 3% {0.07 mag}. With
this improved geometric distance and the BVIH data, we will be able to
the zero point of the PL relation ROBUSTLY to <4% {0.09 mag}.


The Grism-ACS Program for Extragalactic Science {GRAPES}

We propose an ACS grism spectroscopic survey with a wide component and an
ultradeep single ACS field. The wide component covers the well-imaged GOODS
Chandra Deep Field south and the deepest field will be the Ultra Deep field to
be observed in cycles 11 and 12. The Grism ACS Program for Extra-galactic
Science {GRAPES} will: {1} Probe the reionization epoch by robustly determining
the luminosity function of Lyman-alpha emitters, Lyman break galaxies and low
luminosity AGNs at z~6, and thus the sources of ionizing photons at the end of
the "dark ages". A similar census of ionizing photon sources at z=4-6 needed to
maintain the ionized state of the IGM will also be achieved. {2} Study galaxy
formation and evolution by finding galaxies in a contiguous redshift range
between z=4-7 and evolution of black holes through a census of low-luminosity
AGNs. {3} Study star-formation and galaxy assembly at its peak at z=1-2 by
identifying star-forming galaxies by their emission lines, old galaxies by the
4000 AA break and any combination of new and old populations showing both lines
and breaks. {4} Allow the deepest unbiased spectroscopy yet, for identification
of objects to I=27. {5} Enhance the value of multiwavelength data in the
UDF and
GOODS field to the astronomical community.

STIS 9783

The Ages of Nuclear Star Clusters in Early-type Spiral Galaxies

We propose to obtain STIS G430L spectra of the previously identified nuclear
star cluster in a sample of 16 spiral galaxies of early to intermediate Hubble
type. HST’s spatial resolution is required to separate the nuclear cluster from
the underlying galaxy bulge. Analysis of the spectra with population synthesis
methods will reveal the cluster ages. We will use the age distribution to
constrain the duty cycle of nuclear cluster formation. Comparison of the
to those for a larger sample of nuclear clusters in late-type, bulgeless
galaxies will allow us to investigate possible differences between the
mechanisms of nuclear clusters in early and late Hubble types. Such differences
might be expected because galaxy bulges show a dichotomy: in late Hubble types,
the surface brightness profiles are best described by an exponential, while
follow a de Vaucouleurs law in earlier types. Although the reason for this
dichotomy is still unknown, it is plausible that galaxy bulges have different
formation mechanisms at the two ends of the Hubble sequence. We know that {1}
nuclear cluster formation is linked to the funneling of gas towards the nucleus
via gravitational torques from stellar bars, {2} a nuclear mass concentration
can make bars unstable, and {3} unstable bars can form bulges. Therefore, the
age distribution of nuclear star clusters contains important clues to the
evolution of galaxy centers and promises new insight into the origin of the
Hubble sequence.


The local Hubble flow and the density field within 6 Mpc

Great progress has been made recently in accurate distance measurements of
nearby galaxies beyond the Local Group based on the luminosity of the tip
of the
red giant branch {TRGB}. Over the last three years, snapshot surveys with HST
have provided us with the TRGB distances for more than a hundred nearby
obtained with an accuracy of about 10%. The local velocity field within 5 Mpc
exhibits a significant anisotropy which disagrees with a spherical
flow. The local Hubble flow is very cold, with 1-D rms deviations of ~30 km/s.
Cosmological simulations with Cold Dark Matter can only realize such low
dispersions with a combination of a low mean density of matter and a
component with negative pressure. There may be a constraint on the equation of
state w=-p/rho. Our observations will concentrate on 116 galaxies whose
distances lie within 4 – 6 Mpc, allowing us to trace a Dark Matter distribution
in the Local Volume with twice the information currently available. The program
is a good one for SNAP mode because the order and rate that the
observations are
made are not very important, as long as there is good completion over several


Galaxy Evolution During Half the Age of the Universe: ACS imaging of rich

Detailed studies of nearby galaxies {z<0.05} have shown that galaxies have very
complex histories of formation and evolution involving mergers, bursts of star
formation, and morphological changes. Even so, the global properties of the
galaxies {radii, luminosities, rotation velocities, velocity dispersions, and
absorption line strengths} follow a number of very tight {empirical} scaling
relations, e.g. the Tully-Fisher relation and the Fundamental Plane. These
relations place constraints on models for galaxy evolution. The results for
nearby galaxies rely on high signal-to-noise spectroscopy and multi-color
photometry. With the Gemini Telescopes and the Hubble Space Telescope {HST} it
is possible to carry out similar detailed studies of galaxies at much larger
redshifts, up to z~1.0, equivalent to half the age of the Universe. We have
started a project using the scaling relations and aimed at studying the galaxy
evolution over the last half of the age of the Universe. The project is
based on
a large database of spectroscopy and photometry of galaxies in 15 X-ray
clusters of galaxies with redshifts between 0.15 and 1.0. Spectroscopic
observations are being obtained using both Gemini Telescopes; we have
observed 6
clusters so far, covering from z=0.18 to z=0.83. We propose to use HST/ACS to
image the clusters and determine the morphologies and measure the sizes of the
galaxies. At this time we ask for 26 orbits to image four of the clusters
in our

ACS/WFC 9722

Life in the fast lane: The dark-matter distribution in the most massive galaxy
clusters in the Universe at z>0.5

We propose two-filter ACS observations of a complete sample of 12 very X-ray
luminous galaxy clusters at 0.5<z<0.7 as a cornerstone of a comprehensive
multi-wavelength study of the properties of the most massive clusters in the
universe. Our sample includes the famous systems Cl0016+16 and MS0451-03; all
other clusters are new discoveries from the MACS survey. Being the counterparts
of the best-studied systems at lower and higher redshift and comprising ALL
massive clusters at 0.5<z<0.7 observable from Mauna Kea this sample will become
the ultimate reference for cluster studies at z>0.5. HST’s unique capabilities
will allow us to: 1} measure accurately the clusters’ dark matter distribution
on scales from tens to more than 500/h_50 kpc from observations of strong and
weak gravitational lensing, 2} use galaxy-galaxy lensing to measure the shape,
extent, and mass content of the dark-matter halos of both cluster and field
galaxies, and 3} study the color morphology of mergers and the star formation
history of galaxies in a high-density environment. The proposed
observations are
complemented by Chandra observations of all our targets {all 12 awarded, 11
executed to date} which provide independent constraints on the dark matter and
gas distribution in the cluster cores, as well a by extensive groundbased
observations of weak lensing on yet larger scales, galaxy dynamics, and the SZ

WFPC2 9712

Pure Parallel Near-UV Observations with WFPC2 within High-Latitude ACS Survey

In anticipation of the allocation of ACS high-latitude imaging survey{s}, we
request a modification of the default pure parallel program for those WFPC2
parallels that fall within the ACS survey field. Rather than duplicate the red
bands which will be done much better with ACS, we propose to observe in the
near-ultraviolet F300W filter. These data will enable study of the rest-frame
ultraviolet morphology of galaxies at 0<z<1. We will determine the
k-correction, and the location of star formation within galaxies, using a
that is likely to be nearly complete with multi-wavelength photometry and
spectroscopic redshifts. The results can be used to interpret observations of
higher redshift galaxies by ACS.


Resolved halo stellar populations in the Milky Way analogue edge-on galaxy NGC

The stellar halo is one of the fundamental building blocks of galaxies.
ground-based surface photometry has shown that stellar halos exist in some
spiral galaxies, with colours similar to those of the main disk, little else is
known about their stellar populations. We propose to carry out a systematic
study of the halo regions of the edge-on galaxy NGC 891. The resulting deep
colour-magnitude diagrams will be used to infer the mean metallicity of the
bright halo giants at the tip of the RGB and below, and its metallicity spread.
Recently, Zepf et al. {2000} inferred that the halo metallicity of NGC 5907 has
to be low {Fe/H <= -1.7}, with a large stellar M/L ratio. We will be able to
test this hypothesis with much better and deeper data. If we can confirm a
similar halo composition in NGC 891, this would imply that the Milky Way halo
might be very different from external halos. Since galactic halos trace the
history of galaxy formation, this will have important implications for our
understanding of galactic evolution on cosmological time scales. Using these
survey data, we will be able to conclusively distinguish between genuine halo
objects and merger remnants, without having to assume a scenario in which the
halo field population is fully mixed. Surprisingly, such studies have not yet
been undertaken for NGC 891, although the galaxy is a prime Milky Way

HST 9382

A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS QSO
MgII-FeII Systems.

We have searched the first public release of SDSS QSO spectra for low-z
metal absorption lines and found over 200 large rest equivalent width MgII-FeII
systems. Previously, we empirically showed that such systems are good
tracers of
large neutral gas columns, with ~50% being classical damped Lyman alpha {DLA}
systems {N_HI>=2*10^20 cm^-2}. Here we propose to follow up a well-defined
subset of 79 of them to search for DLAs with 0.47<z<1.60. Only QSOs brighter
than g’=19 were selected. The QSO emission and DLA absorption redshifts were
constrained to virtually eliminate data loss due to intervening Lyman limit
absorption. Consequently, we expect to discover ~40 new DLAs, which is a
three-fold increase in this redshift interval. This will significantly improve
our earlier low-z DLA statistical results on their incidence, cosmological mass
density, and N_HI distribution. The results will also allow us to better
quantify the empirical DLA — metal-line correlation. With this improved
understanding, the need for follow-up UV spectroscopy will lessen and, with the
release of the final database of SDSS QSO spectra {an ~25-fold increase}, the
number of low-z DLAs could be increased arbitrarily. Thus, the power of the
large and statistically-sound SDSS database in combination with a proven
technique for finding low-z DLAs will, over the next few years, essentially
solve the problem of making an accurate determination of the cosmic
evolution of
the neutral gas component down to z~0.4.


NICMOS Post-SAA calibration – CR Persistence Part 2

A new procedure proposed to alleviate the CR-persistence problem of NICMOS.
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
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
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

STIS/CCD 10085

STIS Pure Parallel Imaging Program: Cycle 12

This is the default archival pure parallel program for STIS during cycle 12.

WFPC2 10084

WFII parallel archive proposal

This is the generic target version of the WFPC2 Archival Pure Parallel program.
The program will be used to take parallel images of random areas of the sky,
following the recommendations of the 2002 Parallels Working Group.

STIS/MA1 10083

HST UV Images of Saturn’s Aurora Coordinated with Cassini Solar Wind

A key measurement goal of the Cassini mission to Saturn is to obtain
simultaneous solar wind and auroral imaging measurements in a campaign
for Jan. 2004. Cassini will measure the solar wind approaching Saturn
continuously from 9 Jan. – 6 Feb., but not closer to Saturn due to competing
spacecraft orientation constraints. The only system capable of imaging Saturn’s
aurora in early 2004 will be HST. In this community DD proposal we request the
minimum HST time needed to support the Cassini mission during the solar wind
campaign with UV images of Saturn’s aurora. Saturn’s magnetosphere is
intermediate between the "closed" Jovian case with large internal sources of
plasma and the Earth’s magnetosphere which is open to solar wind interactions.
Saturn’s aurora has been shown to exhibit large temporal variations in
brightness and morphology from Voyager and HST observations. Changes of auroral
emitted power exceeding one order of magnitude, dawn brightenings, and
latitudinal motions of the main oval have all been observed. Lacking knowledge
of solar wind conditions near Saturn, it has not been possible to determine its
role in Saturn’s auroral processes, nor the mechanisms controlling the auroral
precipitation. During Cassini’s upcoming approach to Saturn there will be a
unique opportunity to answer these questions. We propose to image one complete
rotation of Saturn to determine the corotational and longitudinal
dependences of
the auroral activity. We will then image the active sector of Saturn once every
two days for a total coverage of 26 days during the Cassini campaign to measure
the upstream solar wind parameters. This is the minimum coverage needed to
ensure observations of the aurora under solar wind pressure variations of more
than a factor of two, based on the solar wind pressure variations measured by
Voyager 2 near Saturn on the declining phase of solar activity. The team of
proposers has carried out a similar coordinated observing campaign of Jupiter
during the Cassini flyby, resulting in a set of papers and HST images on the
cover of Nature on 28 February 2002.

WFPC2 10082

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans

WFPC2 10069

WFPC2 CYCLE 12 Supplemental Darks, Part 1/3

This dark calibration program obtains 3 dark frames every day to provide data
for monitoring and characterizing the evolution of hot pixels.


CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
of hot pixels and test for any source of noise in ACS CCD detectors. This
programme will be executed once a day for the entire lifetime of ACS.

STIS/CCD 10019

CCD Bias Monitor – Part 1

Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1, and 1×1
at gain = 4, to build up high-S/N superbiases and track the evolution of hot

STIS/CCD 10017

CCD Dark Monitor-Part 1

Monitor the darks for the STIS CCD.


Significant Spacecraft Anomalies: (The following are preliminary reports of
potential non-nominal performance that will be investigated.) None



                       SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq           22                        22
FGS REacq           8                          8
FHST Update         47                        47


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