HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 4150
PERIOD COVERED: UT July 6, 2006 (DOY 187)
OBSERVATIONS SCHEDULED
ACS/HRC 10545
Icy planetoids of the outer solar system
Early HST studies of satellites of Kuiper belt object focussed on
the
50-200 km objects that were the largest known at the time. In the past
3
years we have discovered a population of much more rare and much
larger
{500-2000+ km} icy planetoids in the Kuiper belt. These objects are
the
largest and brightest known in the Kuiper belt and, in the era when
we
now know of more than 1000 Kuiper belt objects, these few planetoids
are
likely to be the focus of much of the research on physical properties
of
the outer solar system for years to come. We are currently engaged in
an
intensive program involving Spitzer, Keck, and other telescopes to
study
the physical and dynamical properties of this new population. HST is
uniquely capable of addressing one parameter fundamental to
completing
the physical picture of these planetoids: the existence and size of
any
satellites. The detection and characterization of satellites to
these
large planetoids would allow us to address unique issues critical to
the
formation and evolution of the outer solar system, including the
measurement of densities, internal properties, sizes and shapes of
these
objects, the study of binary formation as a function of primary
size,
and the context of the Pluto-Charon binary. For these bright objects,
a
satellite search takes less than a full orbit, allowing the
opportunity
for a new project on UV spectroscopy of the planetoids to piggyback
at
no added time cost. This poorly explored spectral range has the
potential to show unique signatures of trapped gasses,
cosmochemically
important ices, and complex organic materials.
ACS/HRC 10556
Neutral Gas at Redshift z=0.5
Damped Lyman-alpha systems {DLAs} are used to track the bulk of the
neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy,
they
could only be studied from the ground at redshifts z>1.65. However,
HST
has now permitted us to discover 41 DLAs at z<1.65 in our
previous
surveys. Followup studies of these systems are providing a wealth of
information about the evolution of the neutral gas phase component
of
the Universe. But one problem is that these 41 low-redshift systems
are
spread over a wide range of redshifts spanning nearly 70% of the age
of
the Universe. Consequently, past surveys for low-redshift DLAs have
not
been able to offer very good precision in any small redshift regime.
Here we propose an ACS-HRC-PR200L spectroscopic survey in the
redshift
interval z=[0.37, 0.7] which we estimate will permit us to discover
another 41 DLAs. This will not only allow us to double the number of
low-redshift DLAs, but it will also provide a relatively
high-precision
regime in the low-redshift Universe that can be used to anchor
evolutionary studies. Fortunately DLAs have high absorption
equivalent
width, so ACS- HRC-PR200L has high-enough resoultion to perform this
proposed MgII-selected DLA survey.
ACS/HRC 9746
Binary systems in the Kuiper Belt
The properties of the orbits of Kuiper belt object {KBO} satellites
hold
keys to fundamental insight into masses and densities of KBOs, the
interaction history of the early solar system, the internal structure
of
distant ice-rock bodies, and even the genesis of the Pluto- Charon
binary. Within the past 18 months, 9 KBO satellite systems have been
discovered, allowing for the first time the possibility of
characterizing a sample of KBO satellite orbital properties. We
propose
HRC observations to determine satellite orbits in the 6 best cases.
We
have carefully devised a strategy for each of these 6 systems to
make
maximum use of ground-based observations, previous HST observations,
and
the smallest possible number of new HST observations. Our proposed
observations will efficiently provide highly reliable orbital
solutions
which are critical to achieving the scientific promise available
from
the study of these systems. Our strategy relies heavily on extensive
Monte Carlo simulations to define optimal times of observing such
that
each new point obtained gives maximum leverage for refining the
orbital
solution. We find that with this strategy we can provide mass
solutions
for all 6 systems to an accuracy of better than 10% using only 25
new
HST observations. This highly efficient program provides extreme
scientific output with optimal use of scarce resources.
ACS/WFC 10503
The Star Formation Histories of Early Type Dwarf Galaxies in Low
Density
Environments: Clues from the Sculptor Group
We seek HST ACS/WFC time to conduct a detailed study of the stellar
populations of 5 early-type {dE, dE/dIrr} dwarf galaxies in the
nearby
{~1.5 to 4 Mpc} Sculptor group. Four of these systems have been
recently
found to contain modest amounts of HI, and existing ground-based and
HST
snapshot data point to the potential presence of small populations
of
young {blue} stars in at least three of these systems. Consequently,
they resemble the Local Group 'transition' objects Phoenix and LGS3.
The
relative number of such transition systems is thus substantially
larger
in the low density environment of the Scl group than for the Local
Group. Detailed stellar populations studies will allow estimation of
the
star formation histories, via stellar population modelling of the
color-magnitude diagrams, of the target dwarfs, which in turn will
connect to gas consumption and retention rates. For the two nearer
dwarfs we aim to reach below the horizontal branch {a first for any
system beyond the Local Group} equivalent to a main sequence turnoff
age
of ~1 Gyr. The observations of these two systems will also allow
detection of RR Lyrae variables and thus direct confirmation of the
presence of old populations. For the other three dwarfs will we
cover
the first 2.5 mags of the red giant branch, equivalent to the main
sequence termination for a ~300 Myr population. The results will
have
implications for theories of galaxy formation and evolution,
particularly with regard to the evolutionary relation between low
luminosity dEs and dwarf irregulars.
ACS/WFC/HRC 11005
Funcional test - MEB2 switch
This is a functional test to be executed after the switch to MEB2.
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 10510
Morphology of massive early-type galaxies at z>1.2: constraining
galaxy
formation models
We ask for NICMOS-NIC2 H-band imaging of a sample of 10 massive
early-type galaxies spectroscopically identified at 1.2<z<1.7. Our
aim
is to look for possible relics of merging events of their
formation/evolution in their morphology. The requested observations,
sampling their rest-frame at lambda>6500A, would map the mass
distribution of the bulk of their stellar content. The targets have
been
revealed by our group on the basis of near-IR spectroscopy obtained
in
the framework of a spectroscopic survey of a complete sample of
bright
EROs {Ks<18.5}. Optical and near-IR photometry is available for all
the
targets, and low resolution near-IR spectra have allowed their
identification and redshift measurement. Spectroscopic and
photometric
data in our hands show that they have already assembled stellar
masses
greater than 3 10^11 solar masses, and that the mean age of their
stellar population is estimated older than 2-3 Gyr for 6 of them and
about 1 Gyr for the other 4 galaxies. Thus, they are among the most
luminous and massive evolved galaxies detected so far at z>1. Other
data
are needed to infer how they have assembled such high stellar
masses,
i.e. to trace back their evolution. The requested observations would
allow us to reveal signs of past interaction/merger event. A smooth
r^{1/m} profile, coupled with no other signs of interaction/merger
{disturbed morphology}, would place the possible merger event of
formation 1-2 Gyr before their redshift z pprox 1.5, i.e. at z > 2-
3.
On the other hand, if signs of recent merger events will be found,
the
last merger event forming the local massive spheroids will be
constrained at 1.5 < z < 2. Thus, the requested HST observations
will
allow for the first time to see how massive early-type galaxies at z
pprox 1.5 look like, constraining in any case the redshift of the
possible merging event of their formation.
NIC2 10849
Imaging Scattered Light from Debris Disks Discovered by the Spitzer
Space Telescope around 21 Sun-like Stars
We propose to use the high-contrast capability of the NICMOS
coronagraph
to image a sample of newly discovered circumstellar disks associated
with Sun-like stars. These systems were identified by their strong
thermal infrared {IR} emission with the Spitzer Space Telescope as
part
of the Spitzer Legacy Science program titled "The Formation and
Evolution of Planetary Systems" {FEPS, P.I.: M.Meyer}. Modeling of
the
thermal excess emission from the spectral energy distributions alone
cannot distinguish between narrowly confined high-opacity disks and
broadly distributed, low-opacity disks. By resolving light scattered
by
the circumstellar material, our proposed NICMOS observations can
break
this degeneracy, thus revealing the conditions under which planet
formation processes are occuring or have occured. For three of our
IR-excess stars that have known radial-velocity planets, resolved
imaging of the circumstellar debris disks may further offer an
unprecedented view of planet-disk interactions in an extrasolar
planetary system. Even non-detections of the light scattered by the
circumstellar material will place strong constraints on the disk
geometries, ruling out disk models with high optical depth. Unlike
previous disk imaging programs, our program contains a well-defined
sample of ~1 solar mass stars covering a range of ages from 3 Myr to
3
Gyr, thus allowing us to study the evolution of disks from primordial
to
debris for the first time. The results from our program will greatly
improve our understanding of the architecture of debris disks around
Sun-like stars, and will create a morphological context for the
existence of our own solar system. This proposal is for a
continuation
of an approved Cycle 14 program {GO/10527, P.I.: D. Hines}.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary
reports
of potential non-nominal performance that will be investigated.)
HSTARS:
10344 - GSAcq(2,3,2) Failed to RGA Control @ 187/2026z
The
GSAcq(2,3,2) scheduled for 187/20:26:03 - 20:34:08 failed to RGA
hold due
to stop flag (QF2STOPF) indication on FGS-2. Pre-acquisition
OBADs had
(RSS) attitude error corrections values of 3017.15 and 9.93
arcseconds. Post-acquisition OBAD/MAP at 187/20:34:07 had (RSS)
error
correction
of 3.55 arcseconds. Possible Observations affected: ACS 194
thru 196.
REacqs(2,3,2) scheduled for 187/22:00:01, 187/23:36:00, both
failed to
RGA Hold due to stop flag on FGS-2. However the REacq at
188/01:12:29 was successful.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FAILURE TIMES
FGS
GSacq
9
8
187/2026z (HSTAR 10344)
FGS
REacq
6
4
187/2200z, 187/2336z (HSTAR 10344)
OBAD with Maneuver
31
31
SIGNIFICANT EVENTS: (None)
-Lynn
Lynn F. Bassford
CHAMP HST Missions Operations Manager
Lockheed Martin Technical Operations
GSFC PH#: 301-286-2876
"The Hubble Space Telescope is the Babe Ruth of astronomical
observatories, the Muhammad Ali of cosmic photography
"
- Robert Roy Britt, space.com 7-14-4
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