Daily Report #4164

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4164

PERIOD COVERED: UT July 26, 2006 (DOY 207)

OBSERVATIONS SCHEDULED

ACS/HRC 10738

Earth Flats

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 in the pipeline and to monitor any changes. Weekly
coronagraphic monitoring is required to assess the changing position
of the spots.

ACS/HRC 10800

Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have
relatively fragile test particles which can be used as tracers of the
early dynamical evolution of the outer Solar System. We propose to
continue a Snapshot program using the ACS/HRC that has a demonstrated
discovery potential an order of magnitude higher than the HST
observations that have already discovered the majority of known
transneptunian binaries. With this continuation we seek to reach the
original goals of this project: to accumulate a sufficiently large
sample in each of the distinct populations collected in the Kuiper
Belt to be able to measure, with statistical significance, how the
fraction of binaries varies as a function of their particular
dynamical paths into the Kuiper Belt. Today's Kuiper Belt bears the
imprints of the final stages of giant-planet building and migration;
binaries may offer some of the best preserved evidence of that
long-ago era.

ACS/HRC 10805

ACS Imaging of Uranus' Atmosphere Near Equinox

Uranus' 97-degree spin axis inclination results in the largest
fractional seasonal variation of solar insolation in the solar system.
Uranus is now close to its 7 December 2007 equinox, and we can now see
most of the northern hemisphere, which was in darkness when Voyager
provided our first detailed view of the planet in 1986. If Uranus'
seasonal response has the large phase shift expected from its long
radiative time constant, it should now exhibit nearly maximal
hemispheric contrast. Although the long time constant also suggests a
small physical response, significant hemispheric asymmetries in cloud
structure and dynamics are becoming apparent. We propose a detailed
characterization of Uranus' current response to this forcing with a
10-orbit program consisting of 4 orbits of WFC imaging with narrowband
ramp filters and 6 orbits of HRC imaging using both broadband and
narrowband filters. Nine narrow-band filters between 0.62 and 0.955
microns will provide vertical sensing depths scanning through the
pressure range where the putative methane and deeper H2S clouds might
plausibly exist and provide strong constraints on their optical
properties and parent gas mixing ratios. The high resolution HRC
images will characterize the dynamics of discrete features at the
15-30 hour time scale unavailable from the ground. Short wavelength
HRC images will enable a characterization of the stratospheric haze.
These observations have unique combinations of spectral range and
resolution with needed temporal and spatial resolution not available
from groundbased observations.

ACS/HRC/WFC 10758

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 May, 31 2006- Oct, 1- 2006.
The first half of the program has a different proposal number: 10729.

ACS/WFC 10846

The Halo Structure of RCS2-2327.4-0204

We propose ACS, NICMOS, and Chandra observations of the central region
of the extraordinary and newly discovered galaxy cluster:
RCS2-2327.4-0204 at z=0.700. This cluster shows 3 or more arcs in
ground-based imaging, with an Einstein radius of 49". Such a large
Einstein radius {3-4 times larger than seen in most clusters} has been
seen in precisely one other cluster in the universe - namely Abell
1689 at z=0.18. From our proposed data we expect to see ~70 lensed
source images, from ~20 image families. We will use both strong and
weak lensing constraints from these data to construct the central mass
profile of the cluster, which, when combined with ground based data
extending to a half degree FOV, will allow us to measure critically
important dark matter halo parameters {such as concentration}. The
target cluster is selected from a large ongoing survey with a
well-defined search volume, which allows us to compare our results to
expectations from simulations. We will also compare the lensing
derived mass profiles to the x-ray equivalent measures; this will
illuminate whether the dominant baryonic component is in equilibrium
with the potential. The area of high magnification behind this cluster
is an order of magnitude larger than typical lensing clusters observed
previously by HST; this order of magnitude increase in area directly
translates into a 10 times better chance for finding very high
redshift galaxies. Many of the highest redshift galaxies found to date
have been found behind massive lensing clusters observed by HST, and
we expect to add to that sample dramatically.

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 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:

#10376 GSAcq (2,1,1) failed due to Scan Step Limit Exceeded on FGS 2 @
207/14:13:41z

Observations affected: ACS 90. Same guide star pair used in HSTAR
10372. OBAD #1: V1 -434.44, V2 3657.35, V3 52.30, RSS 3683.43. OBAD
#2: V1 0.68, V2 -3.06, V3 0.31, RSS 3.15. OBAD MAP @ 207/14:43:41
indicated the following: V1 -781.82, V2 4505.00, V3 -128.39, RSS
4574.14

#10378 GSacq(2,11) failed to RGA control @ 207/18:21:17z

During LOS, GSAcq(2,11) failed due to stop flag QF2STOPF on FGS 2.
OBAD2 showed errors of V1=0.15, V2=-6.58, V3=-6.28, RSS=9.10.
Observation affected: ACS 94

#10379 GSacaq(2,1,1) failed due to scan step limit exceeded on FGS 2 @
207/21:33:08z

This is the same guide star that failed in HSTARs 10372, 10376, and
10378. Observations affected: ACS 97

#10380 GSACQ(2,1,1) failed @ 208/00:43:29z

During LOS, FGS2 scan step flag QF2SSLEX and stop flag QF2STOPF were
set. NICMOS 705 status buffer message (TDF down when a target
acquisition SAM request is made) with parameter 0 and time 32142
occurred at 00:52:39. Further information will be available after next
SSR engineering recorder dump. Observations affected: NICMOS 29 to 31.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 10 06
FGS REacq 03 01
OBAD with Maneuver 26 26

SIGNIFICANT EVENTS: (None)