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Daily Report #4501



 
 
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Old December 6th 07, 06:01 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #4501

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT***** # 4501

PERIOD COVERED: UT December 6, 2007 (DOY 340)

OBSERVATIONS SCHEDULED

FGS 11211

An Astrometric Calibration of Population II Distance Indicators

In 2002 HST produced a highly precise parallax for RR Lyrae. That
measurement resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a
useful result, judged by the over ten refereed citations each year
since. It is, however, unsatisfactory to have the direct,
parallax-based, distance scale of Population II variables based on a
single star. We propose, therefore, to obtain the parallaxes of four
additional RR Lyrae stars and two Population II Cepheids, or W Vir
stars. The Population II Cepheids lie with the RR Lyrae stars on a
common K-band Period-Luminosity relation. Using these parallaxes to
inform that relationship, we anticipate a zero-point error of 0.04
magnitude. This result should greatly strengthen confidence in the
Population II distance scale and increase our understanding of RR
Lyrae star and Pop II Cepheid astrophysics.

WFPC2 11002

A Census of LIRGs in Clusters of Galaxies in the First Half of the
Universe from the IRAC Shallow Survey

The incidence of LIRGs and ULIRGs is roughly two orders of magnitude
higher in the field at redshift z 1, and at these redshifts such
objects dominate the global star formation activity. Mergers which
fuel such activity might be expected to enhance the frequency of LIRGs
in dense environments. We propose to use MIPS to obtain a census of
LIRGs in z 1 galaxy clusters from a well defined sample found in the
IRAC Shallow Survey. Supporting IRAC and HST ACS data are also
requested.

WFPC2 11032

CTE Extended Targets Closeout

Measuring the charge transfer efficiency {CTE} of an astronomical CCD
camera is crucial to determining the CCD's photometric fidelity across
the field of view. WFPC2's CTE has degraded steadily over the last 13
years because of continuous exposure to trapped particles in HST's
radiation environment. The fraction of photometric signal lost from
WFPC2's CTI {change transfer inefficiency} is a function of WFPC2's
time in orbit, the integrated signal in the image, the location of the
image on the CCD, and the background signal. Routine monitoring of
WFPC2's degrading CTE over the last 13 years has primarily concerned
the effects of CTI on point-source photometry. However, most of the
sources imaged by WFPC2 are extended rather than point-like. This
program aims to characterize the effects of CTI on the photometry and
morphology of extended sources near the end of WFPC2's functional
life. Images of a standard field within the rich galaxy cluster Abell
1689 are recorded with each WFPC2 camera using the F606W and F814W
filters. These images will be compared with contemporaneous images of
Abell 1689 recorded with the field rotated by approximately 180
degrees to assess differences between extended sources imaged near and
far from the serial register. The images will also be compared with
similar images recorded in Cycle 8 {Program 8456} to characterize the
rate of CTE degradation over the lifetime of WFPC2.

WFPC2 11169

Collisions in the Kuiper belt

For most of the 15 year history of observations of Kuiper belt
objects, it has been speculated that impacts must have played a major
role in shaping the physical and chemical characteristics of these
objects, yet little direct evidence of the effects of such impacts has
been seen. The past 18 months, however, have seen an explosion of
major new discoveries giving some of the first insights into the
influence of this critical process. From a diversity of observations
we have been led to the hypotheses that: {1} satellite- forming
impacts must have been common in the Kuiper belt; {2} such impacts led
to significant chemical modification; and {3} the outcomes of these
impacts are sufficiently predictable that we can now find and study
these impact-derived systems by the chemical and physical attributes
of both the satellites and the primaries. If our picture is correct,
we now have in hand for the first time a set of incredibly powerful
tools to study the frequency and outcome of collisions in the outer
solar system. Here we propose three linked projects that would answer
questions critical to the multiple prongs of our hypothesis. In these
projects we will study the chemical effects of collisions through
spectrophotometric observations of collisionally formed satellites and
through the search for additional satellites around primaries with
potential impact signatures, and we will study the physical effects of
impacts through the examination of tidal evolution in proposed impact
systems. The intensive HST program that we propose here will allow us
to fully test our new hypotheses and will provide the ability to
obtain the first extensive insights into outer solar system impact
processes.

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 Monte Carlo technique to optimally schedule our
observations.

WFPC2 11312

The Local Cluster Substructure Survey {LoCuSS}: Deep Strong Lensing
Observations with WFPC2

LoCuSS is a systematic and detailed investigation of the mass,
substructure, and thermodynamics of 100 X-ray luminous galaxy clusters
at 0.15z0.3. The primary goal is to test our recent suggestion that
this population is dominated by dynamically immature disturbed
clusters, and that the observed mass-temperature relation suffers
strong structural segregation. If confirmed, this would represent a
paradigm shift in our observational understanding of clusters, that
were hitherto believed to be dominated by mature, undisturbed systems.
We propose to complete our successful Cycle 15 program {SNAP:10881}
which prior to premature termination had delivered robust weak-lensing
detections in 17 clusters, and candidate strongly-lensed arcs in 11 of
these 17. These strong and weak lensing signals will give an accurate
measure of the total mass and structure of the dark matter
distribution that we will subsequently compare with X-ray and Sunyaev
Zeldovich Effect observables. The broader applications of our project
include 1} the calibration of mass-temperature and mass-SZE scaling
relations which will be critical for the calibration of proposed dark
energy experiments, and 2} the low redshift baseline study of the
demographics of massive clusters to aid interpretation of future high
redshift {z1} cluster samples. To complete the all-important high
resolution imaging component of our survey, we request deep WFPC2
observations of 20 clusters through the F606W filter, for which
wide-field weak-lensing data are already available from our Subaru
imaging program. The combination of deep WFPC2 and Subaru data for
these 20 clusters will enable us to achieve the science program
approved by the Cycle 15 TAC.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

11087 - GSAcq(1,2,2) requires multiple attempts to achieve CT-DV

OTA SE review of PTAS processing revealed that GSAcq(1,2,2) on day
333/04:07:32z required two attempts to achieve CT-DV on FGS1. The
acquisition was successful.

11090 - REACQ(2,3,2) fine lock backup on FGS 2

REACQ(2,3,2) at 340/02:18:31 acquired in fine lock backup on FGS 2
only, with QF3STOPF and QSTOP flags set on FGS 3 at 02:22:50. No other
flags were seen. Previous acquisitions at 339/21:31:59, 23:06:44 and
340/00:42:37 were successful

COMPLETED OPS REQUEST:

18160-1 - Null genslews for proposal 11226 - slots 1-12

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL

FGS GSacq************** 06**************** 06
FGS REacq************** 08**************** 08
OBAD with Maneuver **** 30**************** 30

SIGNIFICANT EVENTS: (None)


 




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