Daily 3858

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT #3858

PERIOD COVERED: DOY 131

OBSERVATIONS SCHEDULED

ACS/HRC 10199

The Most Massive Galaxies in the Universe: Double Trouble?

We are proposing an HST snapshot survey of 70 objects with velocity
dispersion larger than 350 km/s, selected from the Sloan Digital Sky
Survey. Potentially this sample contains the most massive galaxies in
the Universe. Some of these objects may be superpositions; HST imaging
is the key to determining if they are single and massive or if they
are two objects in projection. The objects which HST imaging shows to
be single objects are interesting because they potentially harbor the
most massive black holes, and because their existence places strong
constraints on galaxy formation models. When combined with ground
based data already in hand, the objects which HST imaging shows are
superpositions provide valuable information about interaction rates of
early-type galaxies as well as their dust content. They also constrain
the allowed parameter space for models of binary gravitational lenses
{such models are currently invoked to explain discrepancies in the
distribution of lensed image flux ratios and separations}.

ACS/HRC 10377

ACS Earth Flats

High signal sky flats will be obtained by observing the bright Earth
with the HRC and WFC. These observations will be used to verify the
accuracy of the flats currently used by the pipeline and will provide
a comparison with flats derived via other techniques: L-flats from
stellar observations, sky flats from stacked GO observations, and
internal flats using the calibration lamps. Weekly coronagraphic
monitoring is required to assess the changing position of the spots.

ACS/HRC/WFC 10389

ACS CCDs daily monitor - Cycle 13 - Part 2

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.

ACS/WFC 10374

ACS photometric Stability

This program consists of three parts. In the first part we will
observe a subset of the ACS white dwarfs with HRC and ACS to verify
repeatability to ~0.2%, because the filter shifts are based on
photometric differences between stars of ~1%. These observations are
also required to establish relative magnitudes of the primary WD
standards at the 0.1% level. Targets should be GD153 and G191B2B,
which seems to have the largest V mag error of ~0.008 mag. One orbit
on the most important filters, including the grism and the prisms,
should be expended with each camera for both stars for a total of 4
orbits. In the second part will observe with HRC and WFC a solar
analog star, P330E, to estimate any shifts in the short and the long
wavelength cutoffs of selected filters. Complete filter bandpasses can
be derived directly from the ratio of grism observations with and
without the filter in place. The grism is on filter wheel 1, while
four filters of interest F330W, F344N, F660N, and F814W are on wheel
2. Each grism observation requires 3 settings: filter alone,
filter+grism, and grism alone. In the third part we obtain high S/N
photometric and spectroscopic observations of three red stars, VB-8
{M7}, 2M0038+18 {L3.5} and 2M0559-14 {T5} with HRC and WFC to verify
the photometry at the new standard position and to obtain accurate
calibration {1% or better} of the grism spectra.

ACS/WFC 10429

Streaming Towards Shapley: The Mass of the Richest Galaxy

Concentration in the Local Universe The 600 km/s motion of the Local
Group {LG} with respect to the cosmic microwave background {CMB} is
now known to high accuracy. However, its precise origin remains poorly
understood. The contribution to the motion from the pull of the rich
Shapley supercluster at z = 0.048 is particularly controversial. This
extreme mass concentration contains more than 20 Abell clusters within
35 Mpc of its very rich central cluster A3558, and is recognized as
both the optically richest and the most X-ray luminous structure in
the local {z 0.1} universe. Yet, published values for the mass of
Shapley continue to differ by an order of magnitude, and recent
estimates of its pull on the LG range from negligible {20 km/s} to
highly significant {300 km/s or more}. Here we propose to resolve this
key issue by using ACS to measure high- precision surface brightness
fluctuation {SBF} distances in order to make a direct measurement of
the infall towards Shapley. We will target three Shapley foreground
clusters where the infall is expected to be high {possibly 1000 km/s
or more}, as well as the Shapley core, in order to test the assumption
that it is at rest in the CMB. Prior to ACS, the Shapley region was
unreachable for SBF, but ACS doubles the distance range of the SBF
method with HST, enabling the distances to be measured to the required
accuracy. The proposed measurements will place a firm limit on the
largest mass fluctuation in the nearby universe and finally determine
its contribution to the observed CMB dipole.

FGS 10110

Parallaxes of Extreme Halo Subgiants: Calibrating Globular Cluster
Distances and the Ages of the Oldest Stars

The ages of the oldest stars are a key constraint on the evolution of
our Galaxy, the history of star formation, and cosmological models.
These ages are usually determined from globular clusters. However, it
is alternatively possible to determine ages of extreme Population II
subgiants in the solar neighborhood based on trigonometric parallaxes,
without any recourse to clusters. This approach completely avoids the
vexing issues of cluster distances, reddenings, and chemical
compositions. There are 3 known nearby, extremely metal-deficient Pop
II subgiants with Hipparcos parallax errors of 6-11% which are
available for such age determinations. At present, based on the latest
isochrones, the derived ages of these stars {HD 84937, HD 132475, and
HD 140283} are all close to 14 Gyr, uncomfortably close to or higher
than current estimates of the age of the universe. However, the errors
in the Hipparcos parallaxes imply uncertainties of at least 2 Gyr in
the ages of the 3 stars. We propose to measure parallaxes of these
three Pop II subgiants using HST's Fine Guidance Sensor 1R. We expect
to reduce the Hipparcos parallax error bars by factors of 5-6,
providing the most stringent test yet of current theoretical stellar
models of Pop II stars and pushing the age uncertainties to below 0.5
Gyr. These data will also provide a major new constraint on the
distance scale of globular clusters, with wide implications for
stellar evolution and the calibration of Pop II standard candles.

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 10176

Coronagraphic Survey for Giant Planets Around Nearby Young Stars

A systematic imaging search for extra-solar Jovian planets is now
possible thanks to recent progress in identifying "young stars near
Earth". For most of the proposed young {~ 30 Myrs} and nearby {~ 60
pc} targets, we can detect a few Jupiter-mass planets as close as a
few tens of AUs from the primary stars. This represents the first time
that potential analogs of our solar system - that is planetary systems
with giant planets having semi-major axes comparable to those of the
four giant planets of the Solar System - come within the grasp of
existing instrumentation. Our proposed targets have not been observed
for planets with the Hubble Space Telescope previously. Considering
the very successful earlier NICMOS observations of low mass brown
dwarfs and planetary disks among members of the TW Hydrae Association,
a fair fraction of our targets should also turn out to posses low mass
brown dwarfs, giant planets, or dusty planetary disks because our
targets are similar to {or even better than} the TW Hydrae stars in
terms of youth and proximity to Earth. Should HST time be awarded and
planetary mass candidates be found, proper motion follow-up of
candidate planets will be done with ground-based AOs.

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 10467

SEARCHING FOR LIGHT ECHOES AFTER THE SGR 1806-20- HYPERFLARE

On 2004 December 27, the ``magnetar'' candidate SGR1806-20 experienced
a giant flare, the third detected from Soft Gamma-ray Repeaters since
1979 {GCN Circulars #2920, #2922}. This was by far the most luminous
flare ever observed from a Galactic high energy source {more than
10^46 erg/s}. Following this event, SGR1806-20 was observed and
detected in the radio band {GCN # 2928, #2930} and resolved into two
parts: a point-like and a diffuse component. Our team, based on the
radio position, detected the probable IR counterpart , the first IR
counterpart ever for a SGR, by using the VLT NACO observations carried
out in 2004 {ATel #278}. This DDT proposal is aimed at {a} studying,
in the IR band, the afterglow diffuse component {linked to the giant
flare event}, its shape and expansion rate as a function of time, {b}
tracing back the flux at the onset of the flare through the detection
and study of its scattered-light echoes, {c} searching for jet--like
structures.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

9810 - GSACQ(2,1,1) results in finelock backup (1,0,1) @ 131/1908z The
GSACQ(2,1,1) scheduled at 131/19:08:08 - 19:16:10 during ZOE period,
resulted to finelock backup (1,0,1) using FGS1, due to scan step limit
exceeded indication flag on FGS2 at AOS 131/19:24:15. Prior FM Updates
at 131/19:02:38, 131/19:05:23 showed good attitude error vector at
AOS.

9811 - GSACQ(2,1,1) achives FL DV after multiple attempts @ 131/1942z
The GSACQ(2,1,1) scheduled at 131/19:42:43- 19:50:45 had search radius
limit exceeded on FGS1. Acquisition was successful after multiple
attempts.

OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL FAILURE TIMES
FGS Gsacq 14 14
FGS Reacq 5 5
FHST Update 19 19
LOSS of LOCK

SIGNIFICANT EVENTS: (None)