Notice: For the foreseeable future, the daily reports may contain
apparent discrepancies between some proposal descriptions and the listed
instrument usage. This is due to the conversion of previously approved
ACS WFC or HRC observations into WFPC2, or NICMOS observations
subsequent to the loss of ACS CCD science capability in late January.

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4317

PERIOD COVERED: UT March 12, 2007 (DOY 071)

OBSERVATIONS SCHEDULED

ACS/SBC 10907

Testing the first direct measurement of cataclysmic variable evolution:
the search for a circumbinary disk or a low?mass companion around NN
Serpentis

We obtained high time-resolution photometry using the high speed CCD
camera ULTRACAM between 2002 and 2004, which revealed a gradual
reduction in the orbital period of the pre- cataclysmic variable NN
Serpentis. There are three possible explanations for this period change:
firstly, we may have been successful in obtaining the first and only
direct measurement of the braking rate of a close binary system, in
which case our measured values are approximately 2 orders of magnitude
greater than predicted, and pose serious problems for the theory of
close binary evolution. Secondly, the unusually high braking rate may be
caused by the presence of a circumbinary disk, which would help to
answer two of the outstanding problems with current CV theory - namely
the high mass-transfer rates seen in some CVs, and the fact that the
minimum observed value in the CV period distribution is approximately
15% longer than expected. Finally, our observations could be explained
by a light travel-time effect caused by a third body in orbit around the
binary, which would raise major questions about the evolutionary history
of the system, in particular how a third body has managed to remain in a
stable orbit throughout periods of intense mass-loss in the central
binary. We intend to use IRAC observations to search for a mid-infrared
excess in the spectral energy distribution of NN Ser, which would
confirm the presence of either a disk or a third body. We then propose
to use HST imaging to attempt to resolve a third body, allowing us to
discriminate between the two possibilities. If both methods fail to
reveal any extra system components, we will have ruled out our only
remaining alternatives to a genuinely high angular momentum loss rate in
this system, with profound implications for CV evolution.

WFPC2 11024

WFPC2 CYCLE 15 INTERNAL MONITOR

This calibration proposal is the Cycle 15 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.

FGS 10610

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric
elements {perturbation orbit semi-major axis and inclination} of
extra-solar planets orbiting six stars. These companions were originally
detected by radial velocity techniques. We have demonstrated that FGS
astrometry of even a short segment of reflex motion, when combined with
extensive radial velocity information, can yield useful inclination
information {McArthur et al. 2004}, allowing us to determine companion
masses. Extrasolar planet masses assist in two ongoing research
frontiers. First, they provide useful boundary conditions for models of
planetary formation and evolution of planetary systems. Second, knowing
that a star in fact has a plantary mass companion, increases the value
of that system to future extrasolar planet observation missions such as
SIM PlanetQuest, TPF, and GAIA.

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 10802

SHOES-Supernovae, HO, for the Equation of State of Dark energy

The present uncertainty in the value of the Hubble constant {resulting
in an uncertainty in Omega_M} and the paucity of Type Ia supernovae at
redshifts exceeding 1 are now the leading obstacles to determining the
nature of dark energy. We propose a single, integrated set of
observations for Cycle 15 that will provide a 40% improvement in
constraints on dark energy. This program will observe known Cepheids in
six reliable hosts of Type Ia supernovae with NICMOS, reducing the
uncertainty in H_0 by a factor of two because of the smaller dispersion
along the instability strip, the diminished extinction, and the weaker
metallicity dependence in the infrared. In parallel with ACS, at the
same time the NICMOS observations are underway, we will discover and
follow a sample of Type Ia supernovae at z > 1. Together, these
measurements, along with prior constraints from WMAP, will provide a
great improvement in HST's ability to distinguish between a static,
cosmological constant and dynamical dark energy. The Hubble Space
Telescope is the only instrument in the world that can make these IR
measurements of Cepheids beyond the Local Group, and it is the only
telescope in the world that can be used to find and follow supernovae at
z > 1. Our program exploits both of these unique capabilities of HST to
learn more about one of the greatest mysteries in science.

NIC3 11098

Pinning down the redshift of the J-band dropout JD0910+46

The earliest galaxies in the Universe should have formed at very high
redshifts, based both on models of hierarchical structure formation, and
on observations of the microwave background polarization by WMAP that
require significant ionization of the intergalactic medium before z=10.
However, direct observation of sources at z>7 remains highly challenging
due to their scarcity and faintness. We recently identified a spatially
extended J-band dropout, JD0910+46, that is a promising candidate for a
z>10 galaxy. Its spectral energy distribution is more extreme than any
previously reported: It is undetected in our 2- orbit J-band
observation, with a very red J-H color, yet is bluer in H-K than
plausible lower redshift {z~3} model SEDs. These colors are, however,
natural for a very high redshift star-burst galaxy in which the
Lyman-alpha break has moved mostly or entirely through the F110W band.
Here we propose deeper F110W and F187W observations to better map the
spectral energy distribution of JD910+46, these have the potential to
convincingly reject all low redshift solutions for the origin of the
observed colours. We believe the importance of such a discovery adds
urgency to the followup, and motivates this DD request. Even in the
event that JD0910+46 lies at lower redshift understanding the nature of
the object will be of great importance since it may lie in a significant
overdensity of galaxies at z~4, and will be an important tool for
identifying possible interlopers in samples of ultra high-z galaxies.

WFPC2 10999

Testing the first direct measurement of cataclysmic variable evolution:
the search for a circumbinary disk or a low?mass companion around NN
Serpentis

WFPC2 11023

WFPC2 CYCLE 15 Standard Darks - part 1

This dark calibration program obtains dark frames every week in order to
provide data for the ongoing calibration of the CCD dark current rate,
and to monitor and characterize the evolution of hot pixels. Over an
extended period these data will also provide a monitor of radiation
damage to the CCDs.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:
10737 - REacq(1,2,2) failed due to a STOP flag on FGS 1
           REacq failed after Fine Lock was established on FGS 1.
           OBAD prior RSS 25.73 a-s

          REacq(1,2,2) scheduled at 17:44:21 failed due to SSLEX on FGS 1.
          QF1SSLEX, QSTEPEXC, QF1STOPF and QSTOP were present.
          Pre OBAD RSS 18.57 a-s

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL
FGS GSacq                09                 09
FGS REacq                06                 04
OBAD with Maneuver 25                 25

SIGNIFICANT EVENTS: (None)