Daily #3980
- From: Joe Cooper <jcooper@xxxxxxxxxxxx>
- Date: Tue, 8 Nov 2005 15:40:00 +0000 (UTC)
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3980
PERIOD COVERED: UT November 02, 2005 (DOY 306)
OBSERVATIONS SCHEDULED
ACS/HRC 10116
Towards an Accurate Calibration of the Galactic Cepheid P-L Zero Point
The young open cluster NGC 7790 is unique and astrophysically important
because it contains three classical Cepheid variables {CF Cas, CE Cas A,
and CE Cas B}. If the distance of NGC 7790 were known with certainty,
these Cepheids would define the zero point for the galactic Cepheid
Period-Luminosity {P-L} relationship. By a stroke of good luck, NGC 7790
also contains a 10th-mag eclipsing binary located near the turnoff of
the main-sequence of the color-magnitude diagram of the cluster. This
important eclipsing binary has been little studied until now and
contains two B1IV-V+B3V stars with an orbital period of P=6.005 days.
With HST we propose to secure the accurate distance and reddening of QX
Cas {and thus of the Cepheids} by using eclipsing binaries as precise
standard candles, as we have demonstrated in our work on the Large
Magellanic Cloud. With absolute radii, temperatures, and luminosities of
the stars known from ground-based and HST observations, the method is
essentially geometric and free from many of the uncertainties that
plague other less direct methods. Light and radial velocity curve data
will be combined to determine the physical properties of the eclipsing
binary and thus to secure an accurate distance and reddening for NGC
7790. The determination of the stars' temperatures, reddenings and
chemical abundances, and therefore the cluster's distance, with the
necessary accuracy can only be accomplished with HST. According to our
previous experience, we expect a resulting distance determination with
an accuracy of about 2-3%. Thus, the proposed HST observations could help
eliminate the current nagging uncertainty of the galactic Cepheid zero
point and provide the key for a firm calibration of the P-L
relationship.
ACS/HRC 10525
Characterizing the Near-UV Environment of M Dwarfs: Implications for
Extrasolar Planetary Searches and Astrobiology
We propose SNAP observations with the ACS HRC PR200L prism, designed to
measure the near ultraviolet emission in a sample of 107 nearby M
dwarfs. The sample spans the mass range from 0.1 - 0.6 solar masses
{temperature range 2200K - 4000K} where the UV energy distributions vary
widely between active and inactive stars. The strength and distribution
of this UV emission can have critical consequences for the atmospheres
of attendant planets. Our proposed observations will provide desperately
needed constraints on models of the habitability zone and the
atmospheres of possible terrestrial planets orbiting M dwarf hosts, and
will be used to sharpen TPF target selection. In addition, the NUV data
will be used in conjunction with existing optical, FUV and X-ray data to
constrain a new generation of M dwarf atmospheric models, and to explore
unanswered questions regarding the dynamo generation and magnetic
heating in these low-mass stars.
ACS/HRC 10564
Resolving Ultracool White Dwarf Binaries
We propose an ACS/HRC imaging survey of the coolest white dwarfs known
in order to search for binarity. Current models fail to match observed
spectral energy distributions of these sub- 4000K stellar remnants,
consistently predicting much lower luminosities than observed. A
possible explanation is that they are binary in nature. Because these
cool degenerates have no spectral features, the only way to investigate
their apparent overluminosity is with very high resolution imaging,
which can only be done with HST {these stars are far too faint to be
observed with adaptive optics on the ground}. Optical wavelengths are
ideal because the spectral energy distributions of these old degenerates
peak near 600 nm. With the F435W filter we will be able to partially
resolve equally luminous binaries as close as 0.02", which corresponds
to within 0.6 AU for over half of the 12 proposed target stars. The
collected data will be critical in determining whether these stars
represent the oldest white dwarfs in the solar neighborhood.
ACS/HRC/WFC 10729
ACS CCDs daily monitor
This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise in
ACS CCD detectors. The files, biases and dark will be used to create
reference files for science calibration. This programme will be for the
entire lifetime of ACS. Changes from cycle 13:- The default gain for WFC
is 2 e-/DN. As before bias frames will be collected for both gain 1 and
gain 2. Dark frames are acquired using the default gain {2}. This
program cover the period Oct, 2 2005- May, 29-2006. The second half of
the program has a different proposal number: 10758.
ACS/HRC/WFC 10733
CCD Hot Pixel Annealing
Hot pixel annealing will continue to be performed once every 4 weeks.
The CCD TECs will be turned off and heaters will be activated to bring
the detector temperatures to about +20C. This state will be held for
approximately 6 hours, after which the heaters are turned off, the TECs
turned on, and the CCDs returned to normal operating condition. To
assess the effectiveness of the annealing, a bias and four dark images
will be taken before and after the annealing procedure for both WFC and
HRC. The HRC darks are taken in parallel with the WFC darks. The charge
transfer efficiency {CTE} of the ACS CCD detectors declines as damage
due to on-orbit radiation exposure accumulates. This degradation has
been closely monitored at regular intervals, because it is likely to
determine the useful lifetime of the CCDs. We combine the annealling
activity with the charge transfer efficiency monitoring and also merge
into the routine dark image collection. To this end, the CTE monitoring
exposures have been moved into this proposal . All the data for this
program is acquired using internal targets {lamps} only, so all of the
exposures should be taken during Earth occultation time {but not during
SAA passages}. This program emulates the ACS pre-flight ground
calibration and post-launch SMOV testing {program 8948}, so that results
from each epoch can be directly compared. Extended Pixel Edge Response
{EPER} and First Pixel Response {FPR} data will be obtained over a range
of signal levels for both the Wide Field Channel {WFC}, and the High
Resolution Channel {HRC}.
ACS/SBC 10506
Coordinated observations of Saturn's auroral dynamic morphology and
Cassini plasma measurements
Planetary FUV aurora is the most spectacular signature of the
electrodynamical coupling between the solar wind, the planet's magnetic
field, and its atmosphere. Saturn's magnetosphere has similarities both
with the Earth's magnetosphere, which is 'open' to solar wind
interaction and Jupiter's relatively 'closed' case with its large
internal sources of plasma. HST observations of Saturn's aurora have
shown a much more complex and dynamic morphology than anticipated: a
frequent 'spiral' structure, a changing size of the oval in response to
variations of the solar wind dynamics pressure, and large brightness
changes in a few ten of minutes following compression of the
magnetosphere by the solar wind. In addition, the global morphology and
some spots move at 70% of the planetary co-rotation, while some other
features appear nearly fixed in local time. Recently, ideas have emerged
to account for Saturn's aurora specificities, although many aspects are
still not understood due to the paucity of observational data. Electric
current models suggest that the main oval is located at the limit
between closed and open magnetic field lines, near the magnetopause. The
availability of Cassini in Saturn's magnetic environment now offers a
unique opportunity for collaborative science. We thus propose to test
the relationship between the aurora and conditions at Saturn's
magnetopause {MP} boundary. We plan to image the FUV aurora with ACS at
times of inbound Cassini crossing of the MP from the upstream solar
wind/magnetosheath region into the middle magnetosphere during an
inbound segment of a Cassini's orbit. FUV images will also reveal
whether the main oval changes its size over the interval, possibly
indicating evidence for changes in the amount of open flux in the
system. These HST images of the aurora simultaneous with in situ
measurements of the plasma characteristics and electrodynamics inside
the magnetosphere are critical to obtain key observational tests and
constraints to future ideas and models of Saturn's auroral precipitation
and magnetospheric processes involved.
ACS/SBC 10739
Internal Flat Field Stability
The stability of the CCD flat fields will be monitored using the
calibration lamps and a sub-sample of the filter set. For the SBC
imaging filters, differences in the low-frequency flat field structure
with wavelength will be assessed. New high signal P-flats will be
obtained for the SBC prisms.
ACS/WFC 10491
A Snapshot Survey of the most massive clusters of galaxies
We propose a snapshot survey of a sample of 124 high X-ray luminosity
clusters in the redshift range 0.3-0.7. Similarly luminous clusters at
these redshifts frequently exhibit strong gravitational lensing. The
proposed observations will provide important constraints on the nature
of the cluster mass distributions and a set of optically bright, lensed
galaxies for further 8-10m spectroscopy. We acknowledge the broad
community interest in this sample and waive our data rights for these
observations.
ACS/WFC 10592
An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in the
Local Universe
At luminosities above 10^11.4 L_sun, the space density of far-infrared
selected galaxies exceeds that of optically selected galaxies. These
`luminous infrared galaxies' {LIRGs} are primarily interacting or
merging disk galaxies undergoing enhanced star formation and Active
Galactic Nuclei {AGN} activity, possibly triggered as the objects
transform into massive S0 and elliptical merger remnants. We propose
ACS/WFC imaging of a complete sample of 88 L_IR > 10^11.4 L_sun luminous
infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS: i.e.,
60 micron flux density > 5.24 Jy}. This sample is ideal not only in its
completeness and sample size, but also in the proximity and brightness
of the galaxies. The superb sensitivity, resolution, and field of view
of ACS/WFC on HST enables a unique opportunity to study the detailed
structure of galaxies that sample all stages of the merger process.
Imaging will be done with the F439W and F814W filters {B and I-band} to
examine as a function of both luminosity and merger state {i} the
evidence at optical wavelengths of star formation and AGN activity and
the manner in which instabilities {bars and bridges} in the galaxies may
funnel material to these active regions, {ii} the relationship between
star formation and AGN activity, and {iii} the structural properties
{AGN, bulge, and disk components} and fundamental parameters {effective
radius and surface brightness} of LIRGs and their similarity with
putative evolutionary byproducts {elliptical, S0 and classical AGN host
galaxies}. This HST survey will also bridge the wavelength gap between a
Spitzer imaging survey {covering seven bands in the 3.6-160 micron
range} and a GALEX UV imaging survey of these galaxies, but will resolve
complexes of star clusters and multiple nuclei at resolutions well
beyond the capabilities of either Spitzer or GALEX. The combined
datasets will result in the most comprehensive multiwavelength study of
interacting and merging galaxies to date.
ACS/WFC 10635
Galaxy Transformation as probed by Morphology and Velocity Fields of
Distant Cluster Galaxies
We seek to obtain ACS imaging of four distant {0.3<z<0.6} clusters of
galaxies within a 6'x6' field covered by a 2x2 mosaic to determine
morphological and structural parameters of late-type galaxies. We
specifically concentrate on peculiarities indicative of past or ongoing
interaction processes. The ~90 target galaxies have been {Period74} or
will be {P75} observed with 3D- spectroscopy at ESO-VLT yielding
2D-velocity fields with unprecedented spatial coverage and sampling. The
good spatial resolution of the ground-based data will be further
enhanced by a deconvolution method based on the proposed ACS images. The
velocity field and the morphology in restframe-UV light will reveal
possible transformation mechanisms affecting not only the stellar
populations but also the mass distribution of the galaxies.
Additionally, it will be possible to pin down the nature of the
interaction {e.g. tidally or ram-pressure induced}. This assessment gets
supported by our N-body/SPH simulations {including star formation} of
different interaction processes that allow the direct comparison of
structural and kinematical characteristics at each time step with the
observations on an individual basis taking into account all
observational constraints for a given galaxy. All together, we will be
able to explore the relative efficiency of the various proposed
transformation phenomena. In the case of non-disturbed spirals, a
rotation curve can be extracted from the full 2D velocity field with
unprecedented quality, from which the maximum rotation speed can be
derived with high confidence. In combination with accurate size and
luminosity determinations from the ACS images, we will be able to
establish the Tully-Fisher and Fundamental Plane relations of cluster
spiral members at cosmological epochs. At these distances cluster
assembly is predicted to peak and we can probe the galaxies' luminosity,
size and mass evolution with robust methods. Together with our already
existing sample of ~200 distant {z<=1} spiral galaxies in the field, we
will put strong constraints on current theories of galaxy formation and
evolution in different environments.
NIC1/NIC2/NIC3 8793
NICMOS Post-SAA calibration - CR Persistence Part 4
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 10177
Solar Systems In Formation: A NICMOS Coronagraphic Survey of
Protoplanetary and Debris Disks
Until recently, despite decades of concerted effort applied to
understanding the formation processes that gave birth to our solar
system, the detailed morphology of circumstellar material that must
eventually form planets has been virtually impossible to discern. The
advent of high contrast, coronagraphic imaging as implemented with the
instruments aboard HST has dramatically enhanced our understanding of
natal planetary system formation. Even so, only a handful of evolved
disks {~ 1 Myr and older} have been imaged and spatially resolved in
light scattered from their constituent grains. To elucidate the physical
processes and properties in potentially planet-forming circumstellar
disks, and to understand the nature and evolution of their grains, a
larger spatially resolved and photometrically reliable sample of such
systems must be observed. Thus, we propose a highly sensitive
circumstellar disk imaging survey of a well- defined and carefully
selected sample of YSOs {1-10 Myr T Tau and HAeBe stars} and {> app 10
Myr} main sequence stars, to probe the posited epoch of planetary system
formation, and to provide this critically needed imagery. Our resolved
images will shed light on the spatial distributions of the dust in these
thermally emissive disks. In combination with their long wavelength SEDs
the physical properties of the grains will be discerned, or constrained
by our photometrically accurate surface brightness sensitivity limits
for faint disks which elude detection. Our sample builds on the success
of the exploratory GTO 7233 program, using two- roll per orbit
PSF-subtracted NICMOS coronagraphy to provide the highest detection
sensitivity to the smallest disks around bright stars which can be
imaged with HST. Our sample will discriminate between proposed
evolutionary scenarios while providing a legacy of cataloged
morphologies for interpreting mid- and far-IR SEDs that the recently
launched Spitzer Space Telescope will deliver.
NIC2 10519
Testing the Stellar Coalescence and Accretion Disk Theories of Massive
Star Formation with NICMOS
The importance of massive stars cannot be underestimated - they produce
most of the heavy elements in the universe and dominate the evolution of
the interstellar medium in their vicinity. In spite of their
significance, our understanding of their formation is meager. Both
accretion through disks, analogous to the process of low-mass star
formation, and coalescence of low-mass stars through collisions in the
dense cores of stellar clusters have been suggested. Possibly both
mechanisms occur. High spatial resolution polarization measurements of
the closest massive young stellar objects {YSOs} will enable us to
search for evidence of disk accretion or coalescence in the form of
patterns indicative of light scattered off a coherent disk or off a disk
disrupted by an infalling star, respectively. Here we propose to use 2
micron polarimetry with NICMOS to identify the presence of accretion
disks around massive YSOs or to characterize their environments as
possibly disrupted from a close stellar encounter. There are only a few
sources that meet the stringent selection criteria for this
investigation {even with HST}, which we will examine here. High spatial
resolution is required, but even more important, the point spread
function {PSF} must be stable with time. Furthermore, the PSF must put
minimal flux into large spatial scales, something that cannot be
achieved with adaptive optics. This combination of high Strehl ratio and
stable PSF can only be achieved from space.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports
of potential non-nominal performance that will be investigated.)
HSTARS:
9999 - GSAcq (1,3,1) failed to T2G due to Search Radius Limit Exceeded
on FGS3 @306/1223z
GSAcq(1,3,1) scheduled at 306/12:23:09 - 123:31:13 failed to T2G due to
Search Radius Limit Exceeded on FGS3.
Prior OBAD1 at 306/12:09:24 showed vehicle axis errors: V1=-918.64,
V2=-2238.30, V3=-544.28. 3-axis (RSS) value=2479.95 arcsec.
Prior OBAD2 at 306/12:18:39 showed V1=11.45, V2=46.75, V3=8.25, RSS
value=48.83 arcsec.
Subsequent OPBAD (but no maneuver) at 306/12:31:13 showed V1=0.36,
V2=-23.75, V3=-0.29, RSS=23.75 arcsec.
10001 - GSAcq(1,2,2) required three attempts to achieve CT-DV @301/0810z
GSAcq(1,2,2) required three attempts to achieve CT-DV on FGS1. FGS1
entered Coarse Track for the first time at 08:13:41.135 . It
successfully entered Fine Lock at 08:14:55.985 .
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FAILURE TIMES
FGS GSacq 13 12 306/1223z (HSTAR 9999)
FGS REacq 1 1
OBAD with Maneuver 25 25
SIGNIFICANT EVENTS: (None)
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