Daily Report #4460

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 # 4460

PERIOD COVERED: UT October 02, 2007 (DOY 275)

OBSERVATIONS SCHEDULED

NIC2 10487

A Search for Debris Disks in the Coeval Beta Pictoris Moving Group

Resolved observations of debris disks present us with the opportunity of
studying planetary evolution in other solar systems. We propose to search
for debris disks in the Beta Pictoris moving group {8-20 Myrs, 10-50 pc
away} , which provides a coeval sample of multiple spectral types, and it
has already produced two magnificent resolved debris disks: AU Mic and Beta
Pic. Such coeval sample will provide us with a snapshop of the crucial time
in disk evolution in which the disk makes the transition from optically
thick to optically thin, and it will be useful to study the stellar mass
dependence of the disk evolution.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

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 i mages. Each observation will need its own CRMAP, as
different SAA passages leave different imprints on the NICMOS detectors.

NIC2 11219

Active Galactic Nuclei in nearby galaxies: a new view of the origin of the
radio-loud radio- quiet dichotomy?

Using archival HST and Chandra observations of 34 nearby early-type galaxies
{drawn from a complete radio selected sample} we have found evidence that
the radio-loud/radio-quiet dichotomy is directly connected to the structure
of the inner regions of their host galaxies in the following sense: [1]
Radio-loud AGN are associated with galaxies with shallow cores in their
light profiles [2] Radio-quiet AGN are only hosted by galaxies with steep
cusps. Since the brightness profile is determined by the galaxy's evolution,
through its merger history, our results suggest that the same process sets
the AGN flavour. This provides us with a novel tool to explore the
co-evolution of galaxies and supermassive black holes, and it opens a new
path to understand the origin of the radio-loud/radio-quiet AGN dichotomy.
Currently our analysis is statistically incomplete as the brightness profile
is not available for 82 of the 116 targets. Most galaxies were not observed
with HST, while in some cases the study is obstructed by the presence of
dust features. We here propose to perform an infrared NICMOS snapshot survey
of these 82 galaxies. This will enable us to i} test the reality of the
dichotomic behaviour in a substantially larger sample; ii} extend the
comparison between radio-loud and radio-quiet AGN to a larger range of
luminosities.

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 11176

Location and the Origin of Short Gamma-Ray Bursts

During the past decade extraordinary progress has been made in determining
the origin of long-duration gamma-ray bursts. It has been conclusively shown
that these objects derive from the deaths of massive stars. Nonetheless, the
origin of their observational cousins, short-duration gamma-ray bursts
{SGRBs} remains a mystery. While SGRBs are widely thought to result from the
inspiral of compact binaries, this is a conjecture. A number of hosts of
SGRBs have been identified, and have been used by some to argue that SGRBs
derive primarily from an ancient population {~ 5 Gyr}; however, it is not
known whether this conclusion more accurately reflects selection biases or
astrophysics. Here we propose to employ a variant of a technique that we
pioneered and used to great effect in elucidating the origins of
long-duration bursts. We will examine the degree to which SGRB locations
trace the red or blue light of their hosts, and thus old or young stellar
populations. This approach will allow us to study the demographics of the
SGRB population in a manner largely free of the distance dependent selection
effects which have so far bedeviled this field, and should give direct
insight into the age of the SGRB progenitor population.

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 11201

Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images

In Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in the
Magellanic Clouds centered on background quasars. We used these data to
determine the proper motions of the LMC and SMC to better than 5% and 15%
respectively. These are by far the best determinations of the proper motions
of these two galaxies. The results have a number of unexpected implications
for the Milky Way-LMC-SMC system. The implied three-dimensional velocities
are larger than previously believed, and are not much less than the escape
velocity in a standard 10^12 solar mass Milky Way dark halo. Orbit
calculations suggest the Clouds may not be bound to the Milky Way or may
just be on their first passage, both of which would be unexpected in view of
traditional interpretations of the Magellanic Stream. Alternatively, the
Milky Way dark halo may be a factor of two more massive than previously
believed, which would be surprising in view of other observational
constraints. Also, the relative velocity between the LMC and SMC is larger
than expected, leaving open the possibility that the Clouds may not be bound
to each other. To further verify and refine our results we now request an
epoch of WFPC2/PC data for the fields centered on 40 quasars that have at
least one epoch of ACS imaging. We request execution in snapshot mode, as in
our previous programs, to ensure the most efficient use of HST resources. A
third epoch of data of these fields will provide crucial information to
verify that there are no residual systematic effects in our previous
measurements. More importantly, it will increase the time baseline from 2 to
5 yrs and will increase the number of fields with at least two epochs of
data. This will reduce our uncertainties correspondingly, so that we can
better address whether the Clouds are indeed bound to each other and to the
Milky Way. It will also allow us to constrain the internal motions of
various populations within the Clouds, and will allow us to determine a
distance to the LMC using rotational parallax.

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 09 09
FGS REacq 05 05
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)