Dail Report # 4442
- From: "Cooper, Joe" <jcooper@xxxxxxxxxxxx>
- Date: Fri, 7 Sep 2007 05:30:38 -0700
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 # 4442
PERIOD COVERED: UT September 06, 2007 (DOY 249)
OBSERVATIONS SCHEDULED
WFPC2 11034
WFPC2 Closeout Photometric Characterization
The standard star GRW+70D5829 is observed in filter and chip
combinations that were not included in photometric calibration
programs from 2005, 2006, and 2007. These observations are needed to
complete a library of recent standard star observations taken in all
filter and chip combinations before WFPC2 is decommissioned in SM4.
{Linear Ramp and Polarizer filters are covered in a separate
proposal.} These observations, along with other recent standard star
observations, will be used to study long-term throughput.
WFPC2 11038
Narrow Band and Ramp Filter Closeout
These observations are to improve calibration of narrow band and ramp
filters. We also test for changes in the filter properties during
WFPC2's 14 years on-board HST.
WFPC2 11084
Probing the Least Luminous Galaxies in the Local Universe
We propose to obtain deep color-magnitude data of eight new Local
Group galaxies which we recently discovered: Andromeda XI, Andromeda
XII, and Andromeda XIII {satellites of M31}; Canes Venatici I, Canes
Venatici II, Hercules, and Leo IV {satellites of the Milky Way}; and
Leo T, a new "free-floating" Local Group dwarf spheroidal with
evidence for recent star formation and associated H I gas. These
represent the least luminous galaxies known at *any* redshift, and are
the only accessible laboratories for studying this extreme regime of
galaxy formation. With deep WFPC-2 F606W and F814W pointings at their
centers, we will determine whether these objects contain single or
multiple age stellar populations, as well as whether these objects
display a range of metallicities.
WFPC2 11100
Two new `bullets' for MOND: revealing the properties of dark matter in
massive merging clusters
The principal objective of this proposal is to study the physical
nature of dark matter by using two, massive, newly-identified merging
clusters of galaxies. As shown by the pioneering example of the
``bullet cluster'' {1E0657-56}, such systems are ideal laboratories
for detecting dark matter and distinguishing between cold dark matter
{CDM} and other scenarios {e.g. self-interacting dark matter}. Our
limit on the self-interaction cross-section of dark matter relies on
the assumption of a normal pre-merger mass-to-light ratios, and a
small impact parameter during the collision of the two clusters. In
order to mitigate any possible systematic effects, it is vital to
extend this work to other, similar systems. With detailed observations
of new systems, the systematic uncertainties in the dark matter cross
section calculations can be improved substantially, allowing us to
move from rough order of magnitude estimates to measurements with
quantifiable uncertainties that can be compared usefully with the
predictions from numerical simulations. Our targets are two
extraordinary, high-redshift, merging galaxy clusters recently
discovered by the Massive Cluster Survey {MACS}. This survey is by far
the best matched to this study, since it selects medium redshift
{optimal for gravitational lensing studies} and X-ray luminous {hence
massive} objects. We have selected the best candidates with clear
evidence for considerable offsets between the hot X-ray emitting gas
and optically luminous stellar material. The two most striking
examples are the targets of this proposal. To pin down the position of
the dark matter component we require high resolution, absolutely
calibrated mass maps. The combination of weak and strong lensing
measurements is needed to attain this goal. This can only be achieved
with the excellent resolving power of the HST {in combination with
wide-field, multicolor Subaru data already in hand}. We therefore
request multicolor HST/WFPC2 observations of the two merging clusters.
The combination of constraints from multiply lensed images {identified
via morphology and color information} and high-resolution weak lensing
data will allow us to construct, self-consistently, their mass
distribution from the very centers to the outskirts. Gravitational
lensing thus provides a unique tool transforming these clusters into
dark matter laboratories. They will supply us with answers as to the
nature and properties of dark matter, and how it shapes galaxies and
galaxy clusters and their evolution through cosmic time.
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 05 05
FGS REacq 08 08
OBAD with Maneuver 26 26
SIGNIFICANT EVENTS: (None)
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