Daily #4134

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4134

PERIOD COVERED: UT June 13, 2006 (DOY 164)

OBSERVATIONS SCHEDULED

ACS/HRC 10512

Search for Binaries Among Faint Jupiter Trojan Asteroids

We propose an ambitious SNAPSHOT program to survey faint Jupiter
Trojan asteroids for binary companions. We target 150 objects, with
the expectation of acquiring data on about 50%. These objects span
Vmag = 17.5-19.5, a range inaccessible with ground-based adaptive
optics. We now have a significant sample from our survey of brighter
Trojans to suggest that the binary fraction is similar to that which
we find among brighter main-belt asteroids, roughly 2%. However, our
observations suggest a higher binary fraction for smaller main-belt
asteroids, probably the result of a different formation mechanism
{evident also from the physical characteristics of the binaries}.
Because the collision environment among the Trojans is similar to that
of the Main Belt, while the composition is likely to be very
different, sampling the binary fraction among the fainter Trojans
should help us understand the collisional and binary formation
mechanisms at work in various populations, including the Kuiper Belt,
and help us evaluate theories for the origin of the Trojans.
Calibration of and constraints on models of binary production and
collisional evolution can only be done using these large-scale,
real-life physical systems that we are beginning now to find and
utilize.

ACS/HRC 10547

A SNAP Program to Obtain Complete Wavelength Coverage of Interstellar
Extinction

We propose a SNAP program to obtain ACS/HRC spectra in the near-UV
{PR200L} and near-IR {G800L} for a set of main sequence B stars with
available IUE UV spectrophotometry, optical photometry, and 2MASS IR
photometry. Together with these existing data, the new observations
will provide complete photometric and spectrophotometric coverage from
1150 to 11000 A and enable us to produce complete extinction curves
from the far-UV to the near-IR, with well- determined values of R{V}.
The proposed set of 50 program sight lines includes the full range of
interstellar extinction curve types and a wide range of color
excesses. The new data will allow us to examine variability in the
near-UV through near-IR spectral regions, including the UV-optical
"knee" and the "Very Broad Structure." We will examine the response of
these features to different interstellar environments and their
relationship to other curve features. These are largely unexplored
aspects of extinction curves which will provide additional constraints
on the properties of interstellar grains. The curves will be derived
using stellar atmosphere models to represent the intrinsic spectral
energy distributions of the program stars, eliminating the need to
observe unreddened "standard stars." This approach virtually
eliminates "mismatch error", allowing us to derive extinction curves
with much higher precision than previously possible. In addition, the
new spectra will provide higher S/N data for the peak of the 2175 A
bump than previously available.

ACS/HRC 10559

Astrometric monitoring of binary L and T dwarfs

We propose to obtain high angular resolution ACS images of five binary
L and T dwarfs in order to determine their orbital parameters and
dynamical masses, and directly constrain the evolutionary models of
ultracool and substellar objects. The binaries have estimated periods
ranging between 5 and 14 years. All of them have already been resolved
at least twice {sometimes more} using HST, providing first and second
epochs measurements. We propose to obtain two more ACS imaging
observations separated by 9 to 12 months during cycle 14. The expected
period coverage should therefore range between 35% and 117%, allowing
us to compute precise orbital parameters and masses. Our sample is
large enough and covers a sufficiently wide range of spectral types
{from L3 to T5.5} to allow us to obtain strong constraints the
evolutionnary models.

ACS/HRC/WFC 10514

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 a
Snapshot program using the ACS/HRC that has a potential discovery
efficiency an order of magnitude higher than the HST observations that
have already discovered the majority of known transneptunian binaries.
By more than doubling the number of observed objects in dynamically
hot and cold subpopulations we will be able to answer, with
statistical significance, the question of whether these groups differ
in the abundance of binaries as a result 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/WFC 10523

The Halo Shape and Metallicity of Massive Spiral Galaxies

We propose to resolve the stellar populations of the halos of seven
nearby, massive disk galaxies using a SNAP survey with WFC/ACS. These
observations will provide star counts and color-magnitude diagrams 2-3
magnitudes below the tip of the Red Giant Branch 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 ~31 V-mag per square arcsec. This proposal
will create a unique sampling of galaxy halo properties, as our
targets cover a range in galaxy mass, luminosity, inclination, and
morphology. As function of these galaxy properties this survey will
provide:- the first systematic measurement of radial light profiles
and axial ratios of the diffuse stellar halos and outer disks of
spiral galaxies- a comprehensive analysis of halo metallicity
distributions as function of galaxy type and position within the
galaxy- an unprecedented study of the stellar metallicity and age
distribution in the outer disk regions where the disk truncations
occur- the first comparative study of globular clusters and their
field stellar populations We will use these fossil records of the
galaxy assembly process to test halo formation models within the
hierarchical galaxy formation scheme.

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/HRC 10536

What Are Stalled Preplanetary Nebulae? An ACS SNAPshot Survey

Essentially all planetary nebulae {PNs} are aspherical, whereas the
mass-loss envelopes of AGB stars are strikingly spherical. Our
previous SNAPshot surveys of a morphologically unbiased sample of
pre-planetary nebulae {PPNs} -- objects in transition between the AGB
and PN evolutionary phases -- show that roughly half our observed
targets are resolved, with bipolar or multipolar morphologies.
Spectroscopic observations of our sample confirm that these objects
have not yet evolved into planetary nebulae. Thus, the transformation
from spherical to aspherical geometries has already fully developed by
the time these dying stars have become PPNs. Although our current
studies have yielded exciting results, they are limited in two
important ways -- {1} the number of well-resolved objects is still
small {18}, and the variety of morphologies observed relatively
multitudinous, hence no clear trends can yet be established between
morphology and other source properties {e.g., near-IR, far-IR colors,
stellar spectral type, envelope mass}, and {2} the current samples are
strongly biased towards small PPNs, as inferred from their low
60-to-25 micron flux ratios [R{60/25}1]. However, the prototype of
objects with R{60/25}1, the Frosty Leo Nebula, has a puzzlingly large
post-AGB age {almost 10^4 yr} and a fairly cool central star, very
different from the expectations of single-star stellar evolutionary
models. A proposed, but still speculative, hypothesis for such objects
is that the slow evolution of the central star is due to backflow of
material onto the mass-losing star, retarding its evolution towards
the PN phase. This hypothesis has significant consequences for both
stellar and nebular evolution. We therefore propose a survey of PPNs
with R{60/25}1 which is heavily weighted towards the discovery of
such "stalled PPNs". Supporting kinematic observations using long-slit
optical spectroscopy {with the Keck}, millimeter and radio
interferometric observations {with OVRO, VLA & VLBA} are being
undertaken. The results from this survey {together with our previous
work} will allow us to draw general conclusions about the complex
mass-outflow processes affecting late stellar evolution, and will
provide crucial input for theories of post-AGB stellar evolution. Our
survey will produce an archival legacy of long-standing value for
future studies of dying stars.

WFPC2 10631

Intermediate-Age Globular Clusters in M31

We propose deep ACS/WFC imaging of four halo M31 globular clusters in
order to derive their horizontal branch morphologies. Our
spectroscopic investigation of their integrated light identifies them
as members of an intermediate-age population of globular clusters in
M31. Since our spectroscopic results are based on the analysis of
Balmer absorption lines, we need to secure our results against an
artificial juvenation due to extreme horizontal branch morphologies.
The proposed observations will allow a clear-cut answer to the
question of whether spectroscopically derived intermediate-age
estimates are due to genuinely younger ages or are the result of
anomalously hot horizontal branch morphologies. Either way, our
results will have important implications for spectroscopically derived
ages and metallicities of distant stellar populations. Because of the
high spatial resolution of the proposed ACS/WFC observations we will
also derive accurate surface brightness profiles of our target
globular clusters and investigate the influence of stellar density on
horizontal branch morphology. Moreover, together with deep parallel
WFPC2 fields we will study the metallicity dispersion of the
background stellar population in M31 as a function of galactocentric
radius.

WFPC2 10745

WFPC2 CYCLE 14 INTERNAL MONITOR

This calibration proposal is the Cycle 14 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.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10305 - GSAcq(2,1,2) requires two attempts to achieve CT-DV @
158/1602z

OTA SE review of PTAS processing revealed that GSAcq(2,1,2) required
two attempts to achieve CT-DV on FGS2. The acquisition was successful

10306 - GSAcq(2,1,1) requires two attempts to achieve CT-DV @
158/2303z

OTA SE review of PTAS processing data revealed that GSAcq(2,1,1)
required two attempts to achieve CT-DV on FGS2. The acquisition was
successful.

10307 - GSAcq(2,1,1) requires two attempts to achieve CT-DV @
162/0032z

OTA SE review of PTAS processing revealed that GSACq(2,1,1) required
two attempts to achieve CT-DV. The acquisition was successful.

10309 - OBAD1 failure @ 065/1254z

On 2006/065 at 12:54:23, OBAD 1 using FHSTs 1 & 3 failed with
indication of Attitude Determination Error. The second OBAD at 13:30
using FHSTs 2 & 3 posted a 1 degree correction and the subsequent GS
Acquisition succeeded.

10311 - Zero Gyro +V3 Sunpoint entry @ 164/2035z

At 20:30:13 the 486 ESB error counter SESBSLD incremented due to an
1805 "T2G Moving Target Detected" event. OBAD at 20:34:22 showed
extremely huge errors of V1= -327127.89, V2= -17.1978.30, V3=
-6276.11, RSS= 369633.04 arc seconds with GCHACLO9 = 1. Shortly after
this, telemetry was lost due to HST slewing away from desired
attitude. Telemetry was reacquired in AN format at 20:55, indicating
that vehicle was in "Zero Gyro +V3 Sunpoint". Safemode Fault Recorder
indicates that Magnetic Field Position test (SMAGANGA) failed at
164/20:35:27

COMPLETED OPS REQUEST:
17786-1 - **Contingency BCT Scripts** Appendix A (Early termination of
battery discharge) @ 164/2231z

17785-2 - Battery 1 Capacity Test Script & 5 Battery Pressure Limit COP
(thru step 32) @ 164/2303z

17796-0 - Power on GEA's Following Safing @ 165/0001z
17795-0 - Dump HST486 ESB @ 165/0055z
17797-0 - Transition NICMOS to SAA Oper @ 165/0217z
17798-0 - Recovery from ZGSP (thru step 36) @ 165/0424z


COMPLETED OPS NOTES:
1490-0 - Update SOC Ground Low Yellow Limit value @ 164/1345z

SCHEDULED SUCCESSFUL
FGS GSacq 04 04
FGS REacq 03 03
OBAD with Maneuver 14 14


SIGNIFICANT EVENTS:

Battery 1 Capacity Test Flash Report

Commanding for the Battery 1 Capacity Test started as scheduled on DOY
164/1155 GMT (6/13 at 7:55 am) with the setting of the Battery
Pressure Test for a 5-battery system. Battery 1 was taken off-line and
the discharge began on the first opportunity at 1302 GMT (6/13 at 9:02
am). The discharge was proceeding nominally; however, the test was
terminated upon entry to Zero-Gyro Sunpoint Safemode.

DOY 164/2006 Zero-Gyro Sunpoint (ZGSP) Safemode Flash Report

At GMT 164/20:35:26 the vehicle entered ZGSP Safemode due to the
failure of the Magnetic Field Position safemode test. The initial
investigation shows no signs of hardware issues. The battery 1
capacity test was terminated as expected upon safemode entry with the
removal of the discharge resistor. Contingency Section A of the
Battery Capacity Test script was executed successfully which
reconnected the SA section to the battery and disabled the capacity
test macro. Recovery steps to return the payload safing sequences to
the nominal RTCSs were also performed. HST Safemode Recovery Status

The recovery of HST from the Zero Gyro Sun Point safemode entry is
proceeding nominally. At 165/02:56 HST was transitioned back to Two
Gyro Science mode. An attitude update was uplinked and the aperture
door opened. Recovery procedures have now been completed until uplink
of the Health and Safety (H&S) SMS. The H&S SMS is expected to begin
execution at 165/14:00. The first science SMS will begin at 166/02:00.

The safemode entry was likely caused by the Fixed Head Star Tracker
(FHST) 2 locking on to a satellite at a transition to the Tracker-Two
Gyro (T2G) mode. This was at the stage where FHST data is used to damp
the vehicle rates. As a result, vehicle rates actually accelerated to
over 0.03 degrees/second. The magnetic field angle test failed when
the attitude error exceeded 12 degrees, initiating the Zero Gyro Sun
Point safemode. Evaluation of the event will continue.