HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3785
PERIOD COVERED: DOY 27
OBSERVATIONS SCHEDULED
ACS/WFC 10420
The assembly of a massive galaxy cluster: The 4/h Mpc filament feeding
MACSJ0717.5+3745
We propose a deep ACS/WFC F606W+F814W mosaic of the massive cluster
MACSJ0717.5+3745 at z=0.55 in order to obtain the first direct
detection of cluster evolution through infall of matter along
large-scale filaments. Existing optical, X-ray, and ground based
weak-lensing data show strong evidence of galaxy groups and dark
matter in a coherent structure spanning at least 10 arcmin {4/h Mpc,
LCDM} in the plane of the sky. The size of this object rules out prior
interaction between the groups and the cluster, thus making it a prime
candidate for a genuine filament as opposed to a merger remnant. The
proposed observation will 1} allow the first direct measurement of the
dark matter content and mass distribution along a large-scale filament
via weak lensing, and 2} provide, through galaxy morphology and
resolved colour information, unprecedented insights into the physical
processes and environmental effects governing the transition from
field to cluster galaxies.
ACS/WFC 10429
Streaming Towards Shapley: The Mass of the Richest Galaxy
Concentration in the Local Universe
The 600 km/s motion of the Local Group {LG} with respect to the cosmic
microwave background {CMB} is now known to high accuracy. However, its
precise origin remains poorly understood. The contribution to the
motion from the pull of the rich Shapley supercluster at z = 0.048 is
particularly controversial. This extreme mass concentration contains
more than 20 Abell clusters within 35 Mpc of its very rich central
cluster A3558, and is recognized as both the optically richest and the
most X-ray luminous structure in the local {z < 0.1} universe. Yet,
published values for the mass of Shapley continue to differ by an
order of magnitude, and recent estimates of its pull on the LG range
from negligible {20 km/s} to highly significant {300 km/s or more}.
Here we propose to resolve this key issue by using ACS to measure
high-precision surface brightness fluctuation {SBF} distances in order
to make a direct measurement of the infall towards Shapley. We will
target three Shapley foreground clusters where the infall is expected
to be high {possibly 1000 km/s or more}, as well as the Shapley core,
in order to test the assumption that it is at rest in the CMB. Prior
to ACS, the Shapley region was unreachable for SBF, but ACS doubles
the distance range of the SBF method with HST, enabling the distances
to be measured to the required accuracy. The proposed measurements
will place a firm limit on the largest mass fluctuation in the nearby
universe and finally determine its contribution to the observed CMB
dipole.
ACS/WFC 9744
HST Imaging of Gravitational Lenses
Gravitational lenses offer unique opportunities to study cosmology,
dark matter, galactic structure, galaxy evolution and quasar host
galaxies. They are also the only sample of galaxies selected based on
their mass rather than their luminosity or surface brightness. While
gravitational lenses can be discovered with ground-based optical and
radio observations, converting them into astrophysical tools requires
HST. HST has demonstrated that it can in each case precisely locate
the lens galaxy, measure its luminosity, color and structure, and
search for lensed images of the source host galaxy given the typical
image separations of ~1''. We will obtain ACS/WFC V and I images and
NICMOS H images of 21 new lenses never observed by HST and NICMOS H
images of 16 lenses never observed by HST in the IR. As in previous
cycles, we request that the data be made public immediately.
NIC2 10173
Infrared Snapshots of 3CR Radio Galaxies
Radio galaxies are an important class of extragalactic objects: they
are one of the most energetic astrophysical phenomena and they provide
an exceptional probe of the evolving Universe, lying typically in high
density regions but well-represented across a wide redshift range. In
earlier Cycles we carried out extensive HST observations of the 3CR
sources in order to acquire a complete and quantitative inventory of
the structure, contents and evolution of these important objects.
Amongst the results, we discovered new optical jets, dust lanes,
face-on disks with optical jets, and revealed point-like nuclei whose
properties support FR-I/BL Lac unified schemes. Here, we propose to
obtain NICMOS infrared images of 3CR sources with z<0.3 as a major
enhancement to an already superb dataset. We aim to deshroud dusty
galaxies, study the underlying host galaxy free from the distorting
effects of dust, locate hidden regions of star formation and establish
the physical characteristics of the dust itself. We will measure
frequency and spectral energy distributions of point-like nuclei,
expected to be stronger and more prevalent in the IR, seek spectral
turnovers in known synchrotron jets and find new jets. We will
strongly test unified AGN schemes and merge these data with existing
X-ray to radio observations. The resulting database will be an
incredibly valuable resource to the astronomical community for years
to come.
NICMOS 8790
NICMOS Post-SAA calibration - CR Persistence Part 1.
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.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.) None
COMPLETED OPS REQs: None
OPS NOTES EXECUTED: None
SCHEDULED SUCCESSFUL FAILURE TIMES
FGS Gsacq 6 6
FGS Reacq 11 11
FHST Update 14 14
LOSS of LOCK
SIGNIFICANT EVENTS: None
