Daily Report #4484

Notice: Due to the conversion of some ACS WFC or HRC observations into
WFPC2, or NICMOS observations after the loss of ACS CCD science capability
in January, there may be an occasional discrepancy between a proposal's
listed (and correct) instrument usage and the abstract that follows it.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4484

PERIOD COVERED: UT November 06, 2007 (DOY 310)

OBSERVATIONS SCHEDULED

ACS/SBC 11215

New Sightlines for the Study of Intergalactic Helium: Dozens of
High-Confidence, UV- Bright Quasars from SDSS/GALEX

The reionization of IGM helium is thought to have occurred at redshifts of
z=3 to 4. Detailed study of HeII Lyman-alpha absorption toward a handful of
QSOs at 2.7z3.3 demonstrated the high potential of such IGM probes, but
the critically small sample size limits confidence in cosmological
inferences. The requisite unobscured sightlines to high-z are extremely
rare, but SDSS provides 5800, z3.1 QSOs potentially suitable for HeII
studies. We've cross-correlated SDSS quasars with GALEX UV sources to obtain
dozens of new, high confidence, candidate sightlines {z=3.1-4.9} potentially
useful for detailed HeII studies with HST. We propose brief, 2-orbit
reconnaissance ACS SBC prism exposures toward each of the best dozen new
quasars, to definitively verify UV flux down to HeII. Our combined
SDSS/GALEX selection insures a high confirmation rate, as the quasars are
already known to be UV bright in GALEX. Our program will provide a
statistical sample of HeII sightlines extending to high redshift, enabling
future long exposure follow-up spectra with the SBC prism, or superb quality
COS or STIS spectra after SM4. Stacks of our prism spectra will also
directly yield ensemble information. Ultimately, the new sightlines will
enable confident measures of the spectrum and evolution of the ionizing
background, the evolution of HeII opacity, the epoch of helium reionization,
and the density of IGM baryons.

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 DARKs. 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 11197

Sweeping Away the Dust: Reliable Dark Energy with an Infrared Hubble Diagram

We propose building a high-z Hubble Diagram using type Ia supernovae
observed in the infrared rest-frame J-band. The infrared has a number of
exceptional properties. The effect of dust extinction is minimal, reducing a
major systematic that may be biasing dark energy measurements. Also, recent
work indicates that type Ia supernovae are true standard candles in the
infrared meaning that our Hubble diagram will be resistant to possible
evolution in the Phillip's relation over cosmic time. High signal-to-noise
measurements of 16 type Ia events at z~0.4 will be compared with an
independent optical Hubble diagram from the ESSENCE project to test for a
shift in the derived dark energy equation of state due to a systematic bias.
In Cycle 15 we obtained NICMOS photometry of 8 ESSENCE supernovae and are
awaiting template observations to place them on the IR Hubble diagram. Here
we request another 8 supernovae be studied in the final season of the
ESSENCE search. Because of the bright sky background, H-band photometry of
z~0.4 supernovae is not feasible from the ground. Only the superb image
quality and dark infrared sky seen by HST makes this test possible. This
experiment may also lead to a better, more reliable way of mapping the
expansion history of the universe with the Joint Dark Energy Mission.

NIC3 11334

NICMOS Cycle 16 Spectrophotometry

Observation of the three primary WD flux standards must be repeated to
refine the NICMOS absolute calibration and monitor for sensitivity
degradation. So far, NICMOS grism spectrophotometry is available for only
~16 stars with good STIS spectra at shorter wavelengths. There are more in
the HST CALSPEC standard star data base with good STIS spectra that would
also become precise IR standards with NICMOS absolute SED measurements.
Monitoring the crucial three very red stars (M, L, T) for variability and
better S/N in the IR. Apparent variability was discovered at shorter
wavelengths during the ACS cross-calibration work that revealed a ~2%
discrepancy of the cool star fluxes with respect to the hot primary WD
standards. About a third of these stars are bright enough to do in one
orbit, the rest require 2 orbits.

WFPC2 11029

WFPC2 CYCLE 15 Intflat Linearity Check and Filter Rotation Anomaly Monitor

Intflat observations will be taken to provide a linearity check: the
linearity test consists of a series of intflats in F555W, in each gain and
each shutter. A combination of intflats, visflats, and earthflats will be
used to check the repeatability of filter wheel motions. {Intflat sequences
tied to decons, visits 1-18 in prop 10363, have been moved to the cycle 15
decon proposal xxxx for easier scheduling.} Note: long-exposure WFPC2
intflats must be scheduled during ACS anneals to prevent stray light from
the WFPC2 lamps from contaminating long ACS external exposures.

WFPC2 11038

Narrow Band and Ramp Filter Closeout

These observations are to improve calibration of narrow band and ramp
filters. We also test for changes in the filter properties during WFPC2's 14
years on-board HST.

WFPC2 11202

The Structure of Early-type Galaxies: 0.1-100 Effective Radii

The structure, formation and evolution of early-type galaxies is still
largely an open problem in cosmology: how does the Universe evolve from
large linear scales dominated by dark matter to the highly non-linear scales
of galaxies, where baryons and dark matter both play important, interacting,
roles? To understand the complex physical processes involved in their
formation scenario, and why they have the tight scaling relations that we
observe today {e.g. the Fundamental Plane}, it is critically important not
only to understand their stellar structure, but also their dark-matter
distribution from the smallest to the largest scales. Over the last three
years the SLACS collaboration has developed a toolbox to tackle these issues
in a unique and encompassing way by combining new non-parametric strong
lensing techniques, stellar dynamics, and most recently weak gravitational
lensing, with high-quality Hubble Space Telescope imaging and VLT/Keck
spectroscopic data of early-type lens systems. This allows us to break
degeneracies that are inherent to each of these techniques separately and
probe the mass structure of early-type galaxies from 0.1 to 100 effective
radii. The large dynamic range to which lensing is sensitive allows us both
to probe the clumpy substructure of these galaxies, as well as their
low-density outer haloes. These methods have convincingly been demonstrated,
by our team, using smaller pilot-samples of SLACS lens systems with HST
data. In this proposal, we request observing time with WFPC2 and NICMOS to
observe 53 strong lens systems from SLACS, to obtain complete multi-color
imaging for each system. This would bring the total number of SLACS lens
systems to 87 with completed HST imaging and effectively doubles the known
number of galaxy-scale strong lenses. The deep HST images enable us to fully
exploit our new techniques, beat down low-number statistics, and probe the
structure and evolution of early-type galaxies, not only with a uniform
data-set an order of magnitude larger than what is available now, but also
with a fully coherent and self-consistent methodological approach!

WFPC2 11307

Completing the ACS Nearby Galaxy Survey with WFPC2

We are requesting 25 orbits of Director's Discretionary Time to complete the
primary science goals of our highly-ranked ACS Nearby Galaxy Survey Treasury
program {ANGST}. Our program lost ~2/3 of its orbits due to the ACS failure.
Roughly half of these were restored as a result of an appeal to the
Telescope Time Review Board which re-scoped the program. The Board's
response to our appeal was explicit in terms of which targets were to be
observed and how. We were directed to request Director's discretionary time
for the components of the appeal which were not granted by the Review Board,
but which were vital to the success of the program. The observing strategy
for ANGST is two-fold: to obtain one deep field per galaxy which enables
derivation of an accurate ancient star formation history, and to obtain
radial tilings sufficient for recovering the full star formation history.
The Review Board granted WFPC2 observations for deep fields in 7 galaxies,
but no time for radial tilings. However, recovering the full star formation
history of a galaxy is not possible without additional radial coverage. We
have searched the archives for observations which may be used in place of
the tilings {conceding some of the Treasury goals, but providing significant
constraints on the full star formation history}, and have identified
suitable observations for all but two of the galaxies. Here we request DD
time for radial tilings for those last two galaxies.

WFPC2/ACS/HRC/WFPC 11020

Cycle 15 Focus Monitor

The focus of HST is measured primarily with ACS/HRC over full CVZ orbits to
obtain accurate mean focus values via a well sampled breathing curve. Coma
and astigmatism are also determined from the same data in order to further
understand orbital effects on image quality and optical alignments. To
monitor the stability of ACS to WFPC2 relative focii, we've carried over
from previous focus monitor programs parallel observations taken with the
two cameras at suitable orientations of previously observed targets, and
interspersed them with the HRC CVZ visits.

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: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 06 06
FGS REacq 06 06
OBAD with Maneuver 24 24

SIGNIFICANT EVENTS: (None)