Daily # 4268

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4268

PERIOD COVERED: UT December 27, 2006 (DOY 361)

OBSERVATIONS SCHEDULED

ACS/HRC 11041

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. For cycle 15 the program will cover 18
months 12.1.06-05.31.08 and it has been divied into three different
proposal each covering six months. The three proposals are
11041-11042-11043.

ACS/HRC 11054

Photometric and Spectrophotometric Absolute Calibration

Verify repeatability of the ACS instrumentation on a single bright
star to ?0.2%. Determine any shift in the filter bandpasses since the
preflight lab measurements. Determine the relative magnitude of the 3
primary WD calibrators to 0.1%. Refine the sensitivity calibration of
the CCD prism and grisms at field center and determine the
repeatability accuracy of this calibration. Determine the level of
variability of the three HST red standard stars VB-8 {M7}, 2M0038+18
{L3.5} and 2M0559-14 {T5} and also measure their short wavelength
{7000A} fluxes. Measure the WFC red leak by adding one orbit for WFC
observation of the sdF8 SDSS standard BD+17d4708 in order to look for
continuity vs. SED from O,F,M,L,T.

ACS/WFC 10587

Measuring the Mass Dependence of Early-Type Galaxy Structure

We propose two-color ACS-WFC Snapshot observations of a sample of 118
candidate early- type gravitational lens galaxies. Our lens-candidate
sample is selected to yield {in combination with earlier results} an
approximately uniform final distribution of 40 early-type strong
lenses across a wide range of masses, with velocity dispersions {a
dynamical proxy for mass} ranging from 125 to 300 km/s. The proposed
program will deliver the first significant sample of low-mass
gravitational lenses. All of our candidates have known lens and source
redshifts from Sloan Digital Sky Survey data, and all are bright
enough to permit detailed photometric and stellar- dynamical
observation. We will constrain the luminous and dark-matter mass
profiles of confirmed lenses using lensed-image geometry and
lens-galaxy structural/photometric measurements from HST imaging in
combination with dynamical measurements from spatially resolved
ground-based follow-up spectroscopy. Hence we will determine, in
unprecedented detail, the dependence of early-type galaxy mass
structure and mass-to-light ratio upon galaxy mass. These results will
allow us to directly test theoretical predictions for halo
concentration and star-formation efficiency as a function of mass and
for the existence of a cuspy inner dark- matter component, and will
illuminate the structural explanation behind the fundamental plane of
early-type galaxies. The lens-candidate selection and confirmation
strategy that we propose has been proven successful for high-mass
galaxies by our Cycle 13 Snapshot program {10174}. The program that we
propose here will produce a complementary and unprecedented lens
sample spanning a wide range of lens-galaxy masses.

NIC1 11063

NICMOS Focus Monitoring

This program is a version of the standard focus sweep used since cycle
7. It has been modified to go deeper and uses more narrow filters for
improved focus determination. For Cycle14 a new source has been added
in order to accomodate 2-gyro mode: the open cluster NGC1850. The old
target, the open cluster NGC3603, will be used whenever available and
the new target used to fill the periods when NGC3603 is not visible.
Steps: a} Use refined target field positions as determined from cycle
7 calibrations b} Use MULTIACCUM sequences of sufficient dynamic range
to account for defocus c} Do a 17-point focus sweep, +/- 8mm about the
PAM mechanical zeropoint for each cameras 1 and 2, in 1.0mm steps. d}
Use PAM X/Y tilt and OTA offset slew compensations refined from
previous focus monitoring/optical alignment activities

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 10847

Coronagraphic Polarimetry of HST-Resolved Debris Disks

We propose to take full advantage of the recently commissioned
coronagraphic polarimetry modes of ACS and NICMOS to obtain imaging
polarimetry of circumstellar debris disks that were imaged previously
by the HST coronagraphs, but without the polarizers. It is well
established that stars form in gas-rich protostellar disks, and that
the planets of our solar system formed from a circum-solar disk.
However, the connection between the circumstellar disks that we
observe around other stars and the processes of planet formation is
still very uncertain. Mid-IR spectral studies have suggested that disk
grains are growing in the environments of young stellar objects during
the putative planet-formation epoch. Furthermore, structures revealed
in well resolved images of circumstellar disks suggest gravitational
influences on the disks from co-orbital bodies of planetary mass.
Unfortunately, existing imaging data provides only rudimentary
information abou the disk grains and their environments. Our proposed
observations, which can be obtained only with HST, will enable us to
quantitatively determine the sizes of the grains and optical depths as
functions of their location within the disks {i.e., detailed
tomography}. Armed with these well-determine physical and geometrical
systemic parameters, we will develop a set of self-consistent models
of disk structures to investigate possible interactions between unseen
planets and the disks from which they formed. Our results will also
calibrate models of the thermal emission from these disks, that will
in turn enable us to infer the properties of other debris disks that
cannot be spatially resolved with current or planned instruments and
telescopes.

NIC2 10852

Coronagraphic Polarimetry with NICMOS: Dust grain evolution in T Tauri
stars

The formation of planetary systems is intimately linked to the dust
population in circumstellar disks, thus understanding dust grain
evolution is essential to advancing our understanding of how planets
form. By combining {1} the coronagraphic polarimetry capabilities of
NICMOS, {2} powerful 3-D radiative transfer codes, and {3}
observations of objects known to span the Class II-III stellar
evolutionary phases, we will gain crucial insight into dust grain
growth. By observing objects representative of a known evolutionary
sequence of YSOs, we will be able to investigate how the dust
population evolves in size and distribution during the crucial
transition from a star+disk system to a system containing
planetesimals. When combine with our previous study on dust grain
evolution in the Class I-II phase, the proposed study will help to
establish the fundamental time scales for the depletion of ISM-like
grains: the first step in understanding the transformation from small
submicron sized dust grains, to large millimeter sized grains, and
untimely to planetary bodies.

WFPC2 10915

ACS Nearby Galaxy Survey

Existing HST observations of nearby galaxies comprise a sparse and
highly non-uniform archive, making comprehensive comparative studies
among galaxies essentially impossible. We propose to secure HST's
lasting impact on the study of nearby galaxies by undertaking a
systematic, complete, and carefully crafted imaging survey of ALL
galaxies in the Local Universe outside the Local Group. The resulting
images will allow unprecedented measurements of: {1} the star
formation history {SFH} of a 100 Mpc^3 volume of the Universe with a
time resolution of Delta[log{t}]=0.25; {2} correlations between
spatially resolved SFHs and environment; {3} the structure and
properties of thick disks and stellar halos; and {4} the color
distributions, sizes, and specific frequencies of globular and disk
clusters as a function of galaxy mass and environment. To reach these
goals, we will use a combination of wide-field tiling and pointed deep
imaging to obtain uniform data on all 72 galaxies within a
volume-limited sample extending to ~3.5 Mpc, with an extension to the
M81 group. For each galaxy, the wide-field imaging will cover out to
~1.5 times the optical radius and will reach photometric depths of at
least 2 magnitudes below the tip of the red giant branch throughout
the limits of the survey volume. One additional deep pointing per
galaxy will reach SNR~10 for red clump stars, sufficient to recover
the ancient SFH from the color-magnitude diagram. This proposal will
produce photometric information for ~100 million stars {comparable to
the number in the SDSS survey} and uniform multi-color images of half
a square degree of sky. The resulting archive will establish the
fundamental optical database for nearby galaxies, in preparation for
the shift of high-resolution imaging to the near-infrared.

WFPC2 10990

Dynamical Masses and Third Bodies in the Sirius System

Sirius B is the nearest and brightest of all white dwarfs {WDs}, but
it is fiendishly difficult to observe from the ground because of the
overwhelming brightness of Sirius A. We propose a continuation of our
program of imaging observations of the Sirius system with WFPC2, which
has been underway since 2001. The resulting astrometric data will not
only greatly improve the precision of the binary orbit and the
dynamical mass measurements for both the main-sequence and WD
components, but will also test definitively for the claimed presence
of a third body in this famous system, down to planetary masses. At
present, there is a tantalizing suggestion in our data that there
indeed may exist a substellar or planetary third body in the system.
Our team has also obtained superb spectra of Sirius B using STIS, and
we have achieved an excellent fit to the spectrum using model stellar
atmospheres. However, the implied mass of the WD disagrees
significantly with the dynamical mass implied by the existing
visual-binary orbit {which still has to be based on a combination of
low-accuracy ground-based astrometry plus the small number of existing
HST astrometric observations}. This is another critical motivation for
improving the astrometry.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10579 - OBAD Failed Identification (ESB 1902)

At 361/13:48:02, OBAD1 using trackers FHST-1 and FHST-2 failed. One
486 ESB message 1902 (OBAD Failed Identification) was received. OBAD1
had (RSS) value of 33547.01 arcseconds. OBAD success flag (mnemonic
GCHACL09) returned to the "no success" state (a value of 1). OBAD2 at
361/13:53:04 was successful with (RSS) value of 1366.47 arcseconds.
The subsequent acquisition at 361/14:04:00 was successful.

10580 - GSACQ(2,1,1) failed

GSACQ(2,1,1) at 362/22:37:47 failed to RGA control with QF2STOPF and
QSTOP flags set. No other flags were seen. Vehicle was LOS at time of
failure.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 10 09
FGS REacq 04 04
OBAD with Maneuver 28 27

SIGNIFICANT EVENTS: (None)