Daily Rpt #4682

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT*** #4682

PERIOD COVERED: 5am August 25 - 5am August 26, 2008 (DOY
238/0900z-239/0900z)

OBSERVATIONS SCHEDULED

NIC1 11205

The Affects of Multiplicity on the Evolution of Young Stellar Objects:
A NICMOS Imaging Study

We propose to use NICMOS to investigate the multiplicity of young
stellar objects (YSOs) in the Orion B molecular cloud. Previous
observations with the Spitzer Space Telescope have revealed a
remarkable star forming filament near the NGC 2068 reflection nebula.
The population of YSOs associated with the filament exhibit a
surprisingly wide range of circumstellar evolutionary states, from
deeply embedded protostars to T Tauri accretion disks. Many of the
circumstellar disks themselves show evidence for significant dust
evolution, including grain growth and settling and cleared inner
holes, apparently in spite of the very young age of these stars. We
will estimate the binary fraction of a representative sample of
objects in these various stages of evolution in order to test whether
companions may play a significant role in that evolution.

NIC1/NIC2 11172

Defining Classes of Long Period Variable Stars in M31

We propose a thrifty but information-packed investigation {1440
exposures total} with NICMOS F205W, F160W and F110W providing crucial
information about Long Period Variables in M31, at a level of detail
that has recently allowed the discovery of new variable star classes
in the Magellanic Clouds, a very different stellar population. These
observations are buttressed by an extensive map of the same fields
with ACS and WFPC2 exposures in F555W and F814W, and a massive
ground-based imaging patrol producing well-sampled light curves for
more than 400,000 variable stars. Our primary goal is to collect
sufficient NIR data in order to analyze and classify the huge number
of long-period variables in our catalog {see below} through
Period-Luminosity {P/L} diagrams. We will produce accurate P/L
diagrams for both the bulge and a progression of locations throughout
the disk of M31. These diagrams will be similar in quality to those
currently in the Magellanic Clouds, with their lower metallicity,
radically different star formation history, and larger spread in
distance to the variables. M31 offers an excellent chance to study
more typical disk populations, in a manner which might be extended to
more distant galaxies where such variables are still visible, probing
a much more evenly spread progenitor age distribution than cepheids
{and perhaps useful as a distance scale alternative or cross-check}.
Our data will also provide a massive and unique color-magnitude
dataset, and allow us to confirm the microlensing nature of a large
sample of candidate lensed sources in M31. We expect that this study
will produce several important results, among them a better
understanding of P/L and P/L-color relations for pulsating variables
which are essential to the extragalactic distance ladder, will view
these variables at a common distance over a range of metallicities
{eliminating the distance- error vs. metallicity ambiguity between the
LMC and SMC}, allow further insight into possible faint-variable
mass-loss for higher metallicities, and in general produce a sample
more typical of giant disk galaxies predominant in many studies.

NIC1/NIC2/NIC3 11820

NICMOS Post-SAA Calibration - CR Persistence Part 7

Internals for CR persistence

NIC2 11548

NICMOS Imaging of Protostars in the Orion A Cloud: The Role of
Environment in Star Formation

We propose NICMOS observations of a sample of 252 protostars
identified in the Orion A cloud with the Spitzer Space Telescope.
These observations will image the scattered light escaping the
protostellar envelopes, providing information on the shapes of outflow
cavities, the inclinations of the protostars, and the overall
morphologies of the envelopes. In addition, we ask for Spitzer time to
obtain 55-95 micron spectra of 75 of the protostars. Combining these
new data with existing 3.6 to 70 micron photometry and forthcoming
5-40 micron spectra measured with the Spitzer Space Telescope, we will
determine the physical properties of the protostars such as envelope
density, luminosity, infall rate, and outflow cavity opening angle. By
examining how these properties vary with stellar density (i.e.
clusters vs groups vs isolation) and the properties of the surrounding
molecular cloud; we can directly measure how the surrounding
environment influences protostellar evolution, and consequently, the
formation of stars and planetary systems. Ultimately, this data will
guide the development of a theory of protostellar evolution.

WFPC2 11156

Monitoring Active Atmospheres on Uranus and Neptune

We propose Snapshot observations of Uranus and Neptune to monitor
changes in their atmospheres on time scales of weeks and months.
Uranus equinox is only months away, in December 2007. Hubble Space
Telescope observations during the past several years {Hammel et al.
2005, Icarus 175, 284 and references therein} have revealed strongly
wavelength- dependent latitudinal structure, the presence of numerous
visible-wavelength cloud features in the northern hemisphere, at least
one very long-lived discrete cloud in the southern hemisphere, and in
2006 the first dark spot ever seen on Uranus. Long-term ground-based
observations {Lockwood and Jerzekiewicz, 2006, Icarus 180, 442; Hammel
and Lockwood 2007, Icarus 186, 291} reveal seasonal brightness changes
whose origins are not well understood. Recent near- IR images of
Neptune obtained using adaptive optics on the Keck Telescope, together
with HST observations {Sromovsky et al. 2003, Icarus 163, 256 and
references therein} which include previous Snapshot programs {GO 8634,
10170, 10534} show a general increase in activity at south temperate
latitudes until 2004, when Neptune returned to a rather Voyager-like
appearance. Further Snapshot observations of these two dynamic planets
will elucidate the nature of long-term changes in their zonal
atmospheric bands and clarify the processes of formation, evolution,
and dissipation of discrete albedo features.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of
Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens
a window into dynamical conditions in the protoplanetary disk where
they formed as well as the history of subsequent events which sculpted
the outer Solar System and emplaced them onto their present day
heliocentric orbits. To date, at least 47 TNBs have been discovered,
but only about a dozen have had their mutual orbits and separate
colors determined, frustrating their use to investigate numerous
important scientific questions. The current shortage of data
especially cripples scientific investigations requiring statistical
comparisons among the ensemble characteristics. We propose to obtain
sufficient astrometry and photometry of 23 TNBs to compute their
mutual orbits and system masses and to determine separate primary and
secondary colors, roughly tripling the sample for which this
information is known, as well as extending it to include systems of
two near-equal size bodies. To make the most efficient possible use of
HST, we will use a Monte Carlo technique to optimally schedule our
observations.

WFPC2 11302

WFPC2 CYCLE 16 Standard Darks - Part III

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.

WFPC2 11793

WFPC2 Cycle 16 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.

WFPC2 11795

WFPC2 Cycle 16 UV Earth Flats

Monitor flat field stability. This proposal obtains sequences of earth
streak flats to improve the quality of pipeline flat fields for the
WFPC2 UV filter set. These Earth flats will complement the UV earth
flat data obtained during cycles 8-15.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

#11453 REacq(1,0,1) failed during LOS to RGA only @ 238/1612z due to
Scan Step Limit exceeded on FGS 1. Observations affected: NIC #41 &
42, Proposal ID #11548; and NIC #43, Proposal ID #11820.

#11454 GSAcq(1,2,1) resulted in Fine Lock back-up (1,0,1) @ 239/0157z.
GSAcq 1,2,1 was scheduled from 239/01:53:37-02:01:00z. Possible
observations affected: NICMOS #58-60, Proposal #11548.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

************************** SCHEDULED***** SUCCESSFUL
FGS GSacq******************* 11************ 11
FGS REacq******************* 03************ 02
OBAD with Maneuver********** 28************ 28

SIGNIFICANT EVENTS: (None)