HUBBLE SPACE TELESCOPE - Continuing to
collect World Class Science
DAILY REPORT # 4284
PERIOD COVERED: UT January 23, 2007 (DOY 023)
OBSERVATIONS SCHEDULED
ACS/HRC 10878
An ACS Prism Snapshot Survey for z~2 Lyman Limit Systems
We propose to conduct a spectroscopic survey of Lyman limit absorbers at
redshifts 1.7 < z < 2.2, using ACS/HRC and the PR200L prism. We
have selected 100 quasars at 2.3 < z < 2.6 from the Sloan Digital
Sky Survey Spectroscopic Quasar sample, for which no BAL signature is
found at the QSO redshift and no strong metal absorption lines are
present at z > 2.3 along the lines of sight. The survey has three main
observational goals.
First, we will determine the redshift frequency dN/dz of the LLS over the
column density range 16.3 <log N_HI < 20.3 cm^-2. Second, we will
measure the column density frequency distribution f{N} for the partial
Lyman limit systems {PLLS} over the column density range 16.3 < log
N_HI < 17.5 cm^-2. Third, we will identify new sightlines for
measurements of the primordial D/H ratio. With this survey, we will also
constrain two key quantities of cosmological relevance: First, the
measurements of dN/dz for optically thick LLS and f{N} for the PLLS are
critical to estimating the attenuation of extragalactic ionizing sources
{e.g.
QSOs}. Currently, uncertainties in dN/dz and f{N} are the greatest
sources of uncertainty for inferring the shape and intensity of the UV
background radiation field. Second, we will estimate the amount of metals
in the LLS using the f{N} and ground based observations of metal line
transitions. It is possible that a significant fraction of the
"missing metals" at z~2 are associated with these highly
ionized absorbers. Third, analysis of the LLS lends to investigations of
the interface between galaxies {i.e. the damped Lyman alpha systems} and
the intergalactic medium {i.e. the Lyman alpha forest}. This survey is
ideal for a snapshot observing program, because the on-object integration
times are less than 10 minutes, and the targets cover the majority of the
northern sky.
ACS/HRC 11011
Dissecting An Accretion Disk
We will use 5 epochs of CXO and HST imaging to determine the X-ray and UV
size of the accretion disk of the lensed quasar RXJ1131--1231 using
microlensing. Based on preliminary data, we find that the X-ray source is
roughly 1/10 the size of the accretion disk in the rest- frame B-band.
The new observations will significantly reduce the uncertainties in this
estimate, provide a comparison between the size of the X-ray source and
the size of the accretion disk in the rest frame ultraviolet, and have
the signal-to-noise ratio necessary to begin examining the size of the
hard and soft-band X-ray emission regions separately. The results will
quantitatively test accretion disk theory and X-ray emission
mechanisms.
ACS/SBC 10862
Comprehensive Auroral Imaging of Jupiter and Saturn during the
International Heliophysical Year
A comprehensive set of observations of the auroral emissions from Jupiter
and Saturn is proposed for the International Heliophysical Year in 2007,
a unique period of especially concentrated measurements of space physics
phenomena throughout the solar system. We propose to determine the
physical relationship of the various auroral processes at Jupiter and
Saturn with conditions in the solar wind at each planet.
This can be accomplished with campaigns of observations, with a sampling
interval not to exceed one day, covering at least one solar
rotation.
The solar wind plasma density approaching Jupiter will be measured by the
New Horizons spacecraft, and a separate campaign near opposition in May
2007 will determine the effect of large-scale variations in the
interplanetary magnetic field {IMF} on the Jovian aurora by extrapolation
from near-Earth solar wind measurements. A similar Saturn campaign near
opposition in Jan. 2007 will combine extrapolated solar wind data with
measurements from a wide range of locations within the Saturn
magnetosphere by Cassini. In the course of making these observations, it
will be possible to fully map the auroral footprints of Io and the other
satellites to determine both the local magnetic field geometry and the
controlling factors in the electromagnetic interaction of each satellite
with the corotating magnetic field and plasma density.
Also in the course of making these observations, the auroral emission
properties will be compared with the properties of the near-IR
ionospheric emissions {from ground-based observations} and non thermal
radio emissions, from ground-based observations for Jupiter?s decametric
radiation and Cassini plasma wave measurements of the Saturn Kilometric
Radiation {SKR}.
ACS/SBC 11055
Color dependent SBC Flats
The primary purpose of this program is to check if the low order flat
field of the SBC detector for very red objects is significantly different
from the low order flat field determined from observations of hot
horizontal branch stars. The SBC has recently been discovered to have a
much larger red leak than pre-launch estimates had indicated, and it is
possible that this red leak varies with position on the detector.
Saturn will be used to produce a flat field image suitable for very red
objects and to measure the spatial variation of the red leak.
Examination of STIS G140L spectra of Saturn shows that the continuum flux
from the disk cuts off sharply below about 1550 angstroms. The filter
combination which will best isolate the continuum UV flux of the disk is
the F150LP minus the F165LP. Dithered images in these two filters will be
used to measure the low order flat field as a function of
wavelength.
ACS/WFC 10793
A Survey for Supernovae in Massive High-Redshift Clusters
We propose to continue our ongoing program designed to measure, to an
unprecedented 30% accuracy, the SN-Ia rate in a sample of massive
z=0.5-0.9 galaxy clusters. The SN-Ia rate is a poorly known observable,
especially at high z, and in cluster environments. The SN rate and its
redshift dependence can serve as powerful discrimiminants for a number of
key issues in astrophysics and cosmology. Our observations will: 1.
Put clear constraints on the characteristic SN-Ia "delay time,"
the typical time between the formation of a stellar population and the
explosion of some of its members as SNe-Ia. Such constraints can exclude
entire categories of SN-Ia progenitor models, since different models
predict different delays. 2. Help resolve the question of the dominant
source of the high metallicity in the intracluster medium {ICM} - SNe-Ia,
or core-collapse SNe from an early stellar population with a top-heavy
IMF, perhaps those population III stars responsible for the early
re-ionization of the Universe. Since clusters are excellent laboratories
for studying enrichment {they generally have a simple star-formation
history, and matter cannot leave their deep potentials}, the results will
be relevant for understanding metal enrichment in general, and the
possible role of first generation stars in early Universal enrichment.
Observations obtained so far during cycle 14 yield many SNe in our
cluster fields, but our follow-up campaign reveals most are not in
cluster galaxies. Our interim results indicate a cluster SN rate at the
very low end of the range considered, and its accuracy is limited by the
small number of cluster SNe. We request additional visits to increase the
number of cluster SNe and achieve a measurement that is not limited by
Poisson errors. A detailed progress report is included.
ACS/WFC 10918
Reducing Systematic Errors on the Hubble Constant: Metallicity
Calibration of the Cepheid PL Relation
Reducing the systematic errors on the Hubble constant is still of
significance and of immediate importance to modern cosmology. One of the
largest remaining uncertainties in the Cepheid- based distance scale
{which itself is at the foundation of the HST Key Project determination
of H_o} which can now be addressed directly by HST, is the effect of
metallicity on the Cepheid Period-Luminosity relation. Three chemically
distinct regions in M101 will be used to directly measure and thereby
calibrate the change in zero point of the Cepheid PL relation over a
range of metallicities that run from SMC-like, through Solar, to
metallicities as high as the most metal- enriched galaxies in the pure
Hubble flow. ACS for the first time offers the opportunity to make a
precise calibration of this effect which currently accounts for at least
a third of the total systematic uncertainty on Ho. The calibration will
be made in the V and I bandpasses so as to be immediately and directly
applicable to the entire HST Cepheid-based distance scale sample, and
most especially to the highest-metallicity galaxies that were hosts to
the Type Ia supernovae, which were then used to extend the the distance
scale calibration out to cosmologically significant distances.
ACS/WFC 11024
WFPC2 CYCLE 15 INTERNAL MONITOR
This calibration proposal is the Cycle 15 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A variety
of internal exposures are obtained in order to provide a monitor of the
integrity of the CCD camera electronics in both bays {both gain 7 and
gain 15 -- to test stability of gains and bias levels}, a test for
quantum efficiency in the CCDs, and a monitor for possible buildup of
contaminants on the CCD windows. These also provide raw data for
generating annual super-bias reference files for the calibration
pipeline.
NIC1 10889
The Nature of the Halos and Thick Disks of Spiral Galaxies
We propose to resolve the extra-planar stellar populations of the thick
disks and halos of seven nearby, massive, edge-on galaxies using ACS,
NICMOS, and WFPC2 in parallel. These observations will provide accurate
star counts and color-magnitude diagrams 1.5 magnitudes below the tip of
the Red Giant Branch sampled along the two principal axes and one
intermediate axis of each galaxy. We will measure the metallicity
distribution functions and stellar density profiles from star counts down
to very low average surface brightnesses, equivalent to ~32 V- mag per
square arcsec. These observations will provide the definitive HST study
of extra-planar stellar populations of spiral galaxies. Our targets cover
a range in galaxy mass, luminosity, and morphology and as function of
these galaxy properties we will provide: - The first systematic study of
the radial and isophotal shapes of the diffuse stellar halos of spiral
galaxies - The most detailed comparative study to date of thick disk
morphologies and stellar populations - A comprehensive analysis of halo
and thick disk metallicity distributions as a function of galaxy type and
position within the galaxy. - A sensitive search for tidal streams - The
first opportunity to directly relate globular cluster systems to their
field stellar population We will use these fossil records of the galaxy
assembly process preserved in the old stellar populations to test halo
and thick disk formation models within the hierarchical galaxy formation
scheme. We will test LambdaCDM predictions on sub-galactic scales, where
it is difficult to test using CMB and galaxy redshift surveys, and where
it faces its most serious difficulties.
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 10906
The Fundamental Plane of Massive Gas-Rich Mergers: II. The QUEST
QSOs
We propose deep NICMOS H-band imaging of a carefully selected sample
of
23 local QSOs. This program is the last critical element of a
comprehensive investigation of the most luminous mergers in the nearby
universe, the ultraluminous infrared galaxies {ULIRGs} and the
quasars.
This effort is called QUEST: Quasar / ULIRG Evolutionary STudy. The
high-resolution HST images of the QUEST QSOs will complement an identical
set of images on the ULIRG sample obtained during Cycle 12, an extensive
set of ground-based data that include long-slit NIR spectra from a Large
VLT Program, and a large set of mid-infrared spectra from a Cycle 1
medium-size program with Spitzer. This unique dataset will allow us to
derive with unprecedented precision structual, kinematic, and activity
parameters for a large unbiased sample of objects spanning the entire
ULIRG/QSO luminosity function. These data will refine the fundamental
plane of massive gas-rich mergers and enable us to answer the following
quesitons: {1} Do ultraluminous mergers form elliptical galaxies, and in
particular, giant ellipticals? {2} Do ULIRGs evolve into optical bright
QSOs? The results from this detailed study of massive mergers in the
local universe will be relevant to understanding the basic physical
processes involved in creating massive early-type host on the one hand,
and growing/feeding embedded massive black holes on the other, in major
galaxy mergers. This is an important question since 50% of cosmic star
formation at high-z and most of the big BHs appear to be formed in this
process.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports
of potential non-nominal performance that will be investigated.)
HSTARS:
10643 - ReAcq(1,0,1) failed with F1STOP
HSTAR 10637 originally documented a GSAcq failure and a
ReAcq failure.
The cause of the failures may be different, so this HSTAR is
being
opened to address the ReAcq scheduled for 2007/020
14:05:48.
ReAcq(1,0,1) failed with a stop flag on FGS1.
Original information from HSTAR 10637 regarding reacq:
REacq scheduled at 14:06:10 failed due to stop flag on FGS
1.
1st OBAD RSS 62.00 as
2nd OBAD RSS 11.31 as
REacq failed at 14:10:46 with QF1STOPF and QSTOP flags.
MAP V1 1.69, V2 76.44, V3 -0.62, RSS 76.46 as
At AOS 339/22:34:01 REAcq (2,3,3) scheduled from
339/21:25:01-21:32:33
had failed to RGA control. Only mnemonics QF2STOPF and QSTOP
were
flagging.
OBAD # 1 & 2 data is unavailable due to LOS
OBAD MAP: v1 -8.86, V2 25.03, V3 25.70, RSS 36.95
10644 - ReAcq(2,3,3) failed to RGA hold @ 339/2124z
HSTAR 10544 originally documented two ReAcq failures. The
cause of the
failures may be different, so this HSTAR is being opened to
address the
second ReAcq scheduled for 2006/339/21:24:29. ReAcq(2,3,2)
failed to RGA
hold with stop flag on FGS2.
Additional analysis:
ReAcq(2,3,3) has a missing s-curve in the Y axis of
FGS2.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq
08
08
FGS REacq
07
07
OBAD with Maneuver
30
30
SIGNIFICANT EVENTS: (None)