Daily # 4170

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4170

PERIOD COVERED: UT August 3, 2006 (DOY 215)

OBSERVATIONS SCHEDULED


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/WFC 10911

Calibration of ACS F814W Surface Brightness Fluctuations

The surface brightness fluctuations {SBF} method has emerged as the
primary distance indicator for mapping local large-scale structures
{Virgo, Fornax}, as well as the velocity field out to nearly 15,000
km/s {z 0.05}. This is because other precision distance indicators
either lack the requisite depth {Cepheids, TRGB} or are too rare for
adequate sampling {supernovae}, while more traditional methods
{Tully-Fisher, fundamental plane} lack the necessary precision. The
SBF method is now being used with great success in several major ACS
Wide Field Camera programs. However, whereas the band of choice for
the nearby structure studies has been F850LP, for the distant
large-scale flow studies it is F814W because of its much greater
throughput. As a result, the current calibration for the more distant
studies is inadequate. We propose to establish the first systematic
calibration of the SBF method in the important F814W ACS WFC bandpass.
We will do this by measuring SBF in an optimized sample of galaxies in
the nearby compact Fornax cluster. Given the large amount of effort
and HST time being dedicated to F814W SBF measurements, it is
imperative that we correct this outstanding calibration problem while
time remains. For an extremely modest expenditure of orbits, we will
remove a significant systematic error and vastly improve the overall
accuracy of the ongoing ACS F814W SBF work. These data will also
greatly enhance the legacy value of the HST archive for future SBF
studies.

FGS 10898

The orbit of the most massive known astrometric binary

We have recently used FGS and HRC observations to {a} resolve HD
93129A into two components with very similar optical/UV colors and a
magnitude difference of 0.9 and to {b} detect their relative orbital
motion over a span of 8 years. HD 93129Aa is the prototype O2 If*
star, with an evolutionary mass near 100 M_Sun, while Ab is likely to
be a very early O main-sequence star with a similar or only slightly
smaller mass. Our HST astrometric measurements yield a total mass
above 100 M_Sun, thus confirming the extremely high mass of the
binary, and indicate that the system appears to be approaching
periastron. We request new FGS and HRC observations to {a} calculate
the mass ratio of the system by measuring the orbit of each of the
components with respect to the nearby stars, {b} obtain the periastron
epoch, and {c} start measuring the orbit in order to produce an
estimate of the total mass. These measurements are crucial to shed
light on the value of the stellar upper mass limit.

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.

NIC3 10538

Near-IR Spectrophotometry of 2MASSWJ 1207334-393254B - An Extra-Solar
Planetary Mass Companion

We propose to obtain "short" wavelength near-IR diagnostic and
characterizing spectra of the very high probability candidate
extra-solar giant planet {EGP} companion to 2MASSWJ 1207334-393254
{2M1207}, a young brown dwarf and TW Hydrae Association member. Recent
NICMOS camera 1 multi-band photometric imaging of the companion
candidate, 0.77" {54 AU projected} from 2M1207 - initially detected at
longer wavelengths with VLT/NACO - implicate an object of several
Jupiter masses based on cooling models of EGPs and the likely age of
2M1207 {~ 8 Myr}. Physical companionship of the EGP candidate with
2M1207 has been established at the 99.1% level of confidence via
second- epoch NICMOS astrometric observations. Diagnostic spectra in
the 0.8 to 1.9 micron region {unobtainable from the ground and
overlapping the NICMOS imaging observations} will {a} critically
inform on the physical nature of the EGP, {b} provide currently
non-existing information to test/constrain theoretical models of EGP
properties and evolution, and {c} unequivocally confirm the imaging of
a bone fide EGP. Background light from 2M1207 would normally swamp the
EGP spectrum with direct spectral imaging. To obviate this, we propose
PSF-subtracted grism spectra of the EGP using 2M1207 as its own
spectral template via two-orientation high-contrast image subtraction.
The temporal stability of the HST+NICMOS PSF enables self-subtractions
of targets at different field orientations resulting in contrast
enhancements of 5 to 6 stellar magnitudes in the circumstellar
background at ~ 0.8" at these wavelengths. With the grism field
oriented to place the EGP "above" and "below" 2M1207 {at two
observational epochs} two independent spectra of the EGP will emerge
from a difference image. This prototypical spectrum will serve to test
and improve upon current models of young EGPs which predict flux
suppression by molecular absorption in their atmospheres.


FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST:
17865-0 - Battery 1 Capacity Test Script & 5 Battery Pressure Limit COP
(thru step 39) @ 215/1843z


COMPLETED OPS NOTES: (None)


SCHEDULED SUCCESSFUL
FGS
GSacq 13 13
FGS REacq 01 01
OBAD with Maneuver 28 28


SIGNIFICANT EVENTS:

Battery 1 Capacity Test Flash Report

The Battery 1 discharge terminated at 2006/215 11:45 GMT (7:45 am
local) and the battery was placed back on-line in hardware at 12:18
GMT (8:18 am local). The recovery period began at approximately 12:28
GMT (8:28 am local) with the batteries charging at the K1L4
equivalent. The ROC Trickle Charge Elapse Timer limit was restored to
a nominal 4 orbits at 18:45 GMT (2:45 pm local) and the ROC safemode
test was re-enabled at 18:47 GMT (2:47 pm local). (Continued)

Battery temperatures continue to cycle below 2.0 deg C. Battery 1 is
still scheduled to be placed back on-line in FSW on 216/1655 GMT
(08/04 at 12:55 pm).