Daily # 4225

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4225

PERIOD COVERED: UT October 23, 2006 (DOY 296)

OBSERVATIONS SCHEDULED

ACS/HRC 10556

Neutral Gas at Redshift z=0.5

Damped Lyman-alpha systems {DLAs} are used to track the bulk of the
neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy,
they could only be studied from the ground at redshifts z1.65.
However, HST has now permitted us to discover 41 DLAs at z1.65 in our
previous surveys. Followup studies of these systems are providing a
wealth of information about the evolution of the neutral gas phase
component of the Universe. But one problem is that these 41
low-redshift systems are spread over a wide range of redshifts
spanning nearly 70% of the age of the Universe. Consequently, past
surveys for low-redshift DLAs have not been able to offer very good
precision in any small redshift regime. Here we propose an ACS-HRC-
PR200L spectroscopic survey in the redshift interval z=[0.37, 0.7]
which we estimate will permit us to discover another 41 DLAs. This
will not only allow us to double the number of low-redshift DLAs, but
it will also provide a relatively high-precision regime in the
low-redshift Universe that can be used to anchor evolutionary studies.
Fortunately DLAs have high absorption equivalent width, so
ACS-HRC-PR200L has high-enough resoultion to perform this proposed
MgII-selected DLA survey.

ACS/HRC 10607

Probing Circumstellar and Interstellar Dust with Scattered-Light
Echoes

Scattered-light echoes are one of the most powerful and efficient
probes of the structure and composition of dust in circumstellar and
interstellar {ISM} environments. Observations of light echoes provide
exact three-dimensional positions of dust while constraining its
density, grain- size and chemical make-up. Furthermore, echoes can be
used as distance indicators via polarization measurements. We propose
to take deep, high-resolution ACS/HRC images of five supernovae {SNe}.
Two of these, SNe 1991T and 1998bu, have known circumstellar echoes
that have only recently become fully resolvable with HST, and
therefore require new observations. Only four echo-producing SNe are
currently known, and in an attempt to increase this sample, we will
also observe SNe 1999bw, 2002hh, and 2004dj. All three SNe are strong
candidates for producing echoes from circumstellar and ISM dust, but
only at angular sizes that HST can resolve. With these observations,
we will use light echoes to their full advantage, to study {1} the
mass-loss histories of Type II and Ia SN progenitors, {2} the
contributions of these SNe and their progenitors to the dust content
of their galaxies, {3} the structure of gas and stars in the ISM of
external galaxies, and {4} we will independently measure the distance
to the host galaxies, including a member of the Virgo cluster, and
M96, a Type Ia cosmological distance- scale calibrator.

ACS/HRC/WFC 10733

CCD Hot Pixel Annealing

Hot pixel annealing will continue to be performed once every 4 weeks.
The CCD TECs will be turned off and heaters will be activated to bring
the detector temperatures to about +20C. This state will be held for
approximately 6 hours, after which the heaters are turned off, the
TECs turned on, and the CCDs returned to normal operating condition.
To assess the effectiveness of the annealing, a bias and four dark
images will be taken before and after the annealing procedure for both
WFC and HRC. The HRC darks are taken in parallel with the WFC darks.
The charge transfer efficiency {CTE} of the ACS CCD detectors declines
as damage due to on-orbit radiation exposure accumulates. This
degradation has been closely monitored at regular intervals, because
it is likely to determine the useful lifetime of the CCDs. We combine
the annealling activity with the charge transfer efficiency monitoring
and also merge into the routine dark image collection. To this end,
the CTE monitoring exposures have been moved into this proposal . All
the data for this program is acquired using internal targets {lamps}
only, so all of the exposures should be taken during Earth occultation
time {but not during SAA passages}. This program emulates the ACS
pre-flight ground calibration and post-launch SMOV testing {program
8948}, so that results from each epoch can be directly compared.
Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}
data will be obtained over a range of signal levels for both the Wide
Field Channel {WFC}, and the High Resolution Channel {HRC}.

ACS/HRC/WFC 10758

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. Changes from cycle 13:- The default
gain for WFC is 2 e-/DN. As before bias frames will be collected for
both gain 1 and gain 2. Dark frames are acquired using the default
gain {2}. This program cover the period May, 31 2006- Oct, 1-2006. The
first half of the program has a different proposal number: 10729.

ACS/WFC 10766

A Deep X-ray Survey of the Small Magellanic Cloud

We request deep observations of 2 representative fields in the Small
Magellanic Cloud with Chandra and HST,with the primary goal of
measuring the luminosity function and space density of X-ray binaries
and other sources down to an unprecedented faint luminosity limit of
2x10E32 erg/s. This will be the faintest XLF ever obtained for any
galaxy, including our own. HST photometry to 24th magnitude in V and I
filters will identify the sources and provide Fx/Fopt, which will be
vital in quantifying the LMXB population and in measuring the
properties of the first coronally active stars ever detected in an
external galaxy.

ACS/WFC 10816

The Formation History of Andromeda's Extended Metal-Poor Halo

We propose deep ACS imaging in the outer spheroid of the Andromeda
galaxy, in order to measure the star formation history of its true
halo. For the past 20 years, nearly all studies of the Andromeda
"halo" were focused on the spheroid within 30 kpc of the galaxy's
center, a region now known to host significant substructure and
populations with high metallicity and intermediate ages. However, two
groups have recently discovered an extended metal-poor halo beyond 30
kpc; this population is distinct in its surface-brightness profile,
abundance distribution, and kinematics. In earlier cycles, we obtained
deep images of the inner spheroid {11 kpc on the minor axis}, outer
disk {25 kpc on the major axis}, and giant tidal stream, yielding the
complete star formation history in each field. We now propose deep ACS
imaging of 4 fields bracketing this 30 kpc transition point in the
spheroid, so that the inner spheroid and the extended halo populations
can be disentangled, enabling a reconstruction of the star formation
history in the halo. A wide age distribution in the halo, as found in
the inner spheroid, would imply the halo was assembled through ongoing
accretion of satellite galaxies, while a uniformly old population
would be a strong indication that the halo was formed during the early
rapid collapse of the Andromeda proto-galaxy.

ACS/WFC 10895

Closure on the IRAS "Big Four": A High Contrast Study of Epsilon
Eridani's Dust Belt in Scattered Light.

The ACS / HRC coronagraph has now demonstrated an unmatched capability
to detect dusty debris disks around bright, nearby stars. Among the
"Big Four" debris disks discovered with IRAS twenty years ago, only
Epsilon Eridani {SpT=K2V, d=3.2 pc} has yet to be targeted with ACS.
Beta Pictoris, Fomalhaut and Vega have been imaged with the ACS
coronagraph, with the recent detection of reflected light from
Fomalhaut's dust belt {Kalas, Graham & Clampin 2005}. The direct
detection of dust scattered light around Fomalhaut shows disk
structure and asymmetry that can be directly linked to dynamical
models of planetary perturbation. Here we propose to use the ACS HRC
and WFC to detect Eps Eri's dust belt. A new motivation to attempt
this observations arises from recent 350 micron images that reveal two
dust arcs ~60 AU to the southeast and northwest of the star. Contrary
to previous 850 and 450 micron maps, the northwest arc is brighter
than the southeast arc, and the northwest region has not been targeted
by previous STIS imaging at lower contrast. The optical detection of
dust features around Eps Eri would be significant because a high
resolution optical image, together with Spitzer and sub-mm images,
would help anchor dynamical models of Eps Eri's planetary system, in
addition to providing direct visual indications of disk-planet
interactions.

ACS/WFC/NIC3 10632

Searching for galaxies at z6.5 in the Hubble Ultra Deep Field

We propose to obtain deep ACS {F606W, F775W, F850LP} imaging in the
area of the original Hubble Ultra Deep Field NICMOS parallel fields
and - through simultaneous parallel observations - deep NICMOS {F110W,
F160W} imaging of the ACS UDF area. Matching the extreme imaging depth
in the optical and near-IR bands will result in seven fields with
sufficiently sensitive multiband data to detect the expected typical
galaxies at z=7 and 8. Presently no such a field exist. Our combined
optical and near-IR ultradeep fields will be in three areas separated
by about 20 comoving Mpc at z=7. This will allow us to give a first
assessment of the degree of cosmic variance. If reionization is a
process extending over a large redshift interval and the luminosity
function doesn't evolve strongly beyond z=6, these data will allow us
to identify of the order of a dozen galaxies at 6.5z8.5 - using the
Lyman break technique - and to place a first constrain on the
luminosity function at z6.5. Conversely, finding fewer objects would
be an indication that the bulk of reionization is done by galaxies at
z=6. By spending 204 orbits of prime HST time we will capitalize on
the investment of 544 prime orbits already made on the Hubble Ultra
Deep Field {UDF}. We have verified that the program as proposed is
schedulable and that it will remain so even if forced to execute in
the 2-gyro mode. The data will be non-proprietary and the reduced
images will be made public within 2 months from the completion of the
observations.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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.

NIC3 10996

NICMOS J-band Imaging of Strongly Lensing Clusters

We propose to use deep imaging in the F110W {'J'} band over a large
area to search for highly magnified galaxies around massive lensing
clusters.

WFPC2 10748

WFPC2 CYCLE 14 Standard Darks

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: (None)

COMPLETED OPS REQUEST:
17943-0 - Genslew for proposal 10896 - slot 10 @ 296/1452z
17944-0 - Genslew for proposal 10896 - slot 11 @ 296/1453z

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 11 11
FGS REacq 04 04
OBAD with Maneuver 30 30


SIGNIFICANT EVENTS: (None)