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Daily # 3973



 
 
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Old October 28th 05, 04:01 PM
Joe Cooper
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Default Daily # 3973

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 3973

PERIOD COVERED: UT October 24, 2005 (DOY 297)

OBSERVATIONS SCHEDULED

ACS/HRC/WFC 10729

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 Oct, 2 2005- May, 29-2006. The second half of
the program has a different proposal number: 10758.

ACS/WFC 10500

Exploring the Bottom End of the White Dwarf Cooling Sequence in the
Galactic Open Cluster NGC2158

The recent discovery by our group of an unexpectedly bright and still
unexplained peak in the white dwarf {WD} luminosity function {LF} of the
metal rich, old open cluster NGC6791 casts serious doubts on our
understanding of the physical process which rules the formation and the
cooling of WDs. In order to investigate whether the same problem is
present in other open clusters with different ages and metallicities, we
propose deep ACS/HST observations reaching the bottom end of the WD LFs,
for the first time in a young and so popolous Galactic open cluster:
NGC2158.

ACS/WFC 10523

The Halo Shape and Metallicity of Massive Spiral Galaxies

We propose to resolve the stellar populations of the halos of seven
nearby, massive disk galaxies using a SNAP survey with WFC/ACS. These
observations will provide star counts and color-magnitude diagrams 2-3
magnitudes below the tip of the Red Giant Branch along the two principal
axes and one intermediate axis of each galaxy. We will measure the
metallicity distribution functions and stellar density profiles from
star counts down to very low average surface brightnesses, equivalent to
~31 V-mag per square arcsec. This proposal will create a unique sampling
of galaxy halo properties, as our targets cover a range in galaxy mass,
luminosity, inclination, and morphology. As function of these galaxy
properties this survey will provide:- the first systematic measurement
of radial light profiles and axial ratios of the diffuse stellar halos
and outer disks of spiral galaxies- a comprehensive analysis of halo
metallicity distributions as function of galaxy type and position within
the galaxy- an unprecedented study of the stellar metallicity and age
distribution in the outer disk regions where the disk truncations occur-
the first comparative study of globular clusters and their field stellar
populations We will use these fossil records of the galaxy assembly
process to test halo formation models within the hierarchical galaxy
formation scheme.

ACS/WFC 10550

The Nature of LSB galaxies revealed by their Globular Clusters

Low Surface Brightness {LSB} galaxies encompass many of the extremes in
galaxy properties. Their understanding is essential to complete our
picture of galaxy formation and evolution. Due to their historical
under-representation on galaxy surveys, their importance to many areas
of astronomy has only recently began to be realized. Globular clusters
are superb tracers of the formation histories of galaxies and have been
extensively used as such in high surface brightness galaxies. We propose
to investigate the nature of massive LSB galaxies by studying their
globular cluster systems. No globular cluster study has been reported
for LSB galaxies to date. Yet, both the presence or absence of globular
clusters set very strong constraints on the conditions prevailing during
LSB galaxy formation and evolution. Both in dwarf and giant high surface
brightness {HSB} galaxies, globular clusters are known to form as a
constant fraction of baryonic mass. Their presence/absence immediately
indicates similarities or discrepancies in the formation and evolution
conditions of LSB and HSB galaxies. In particular, the presence/absence
of metal-poor halo globular clusters infers similarities/differences in
the halo formation and assembly processes of LSB vs. HSB galaxies, while
the presence/absence of metal-rich globular clusters can be used to
derive the occurrence and frequency of violent events {such as mergers}
in the LSB galaxy assembly history. Two band imaging with ACS will allow
us to identify the globular clusters {just resolved at the selected
distance} and to determine their metallicity {potentially their rough
age}. The composition of the systems will be compared to the extensive
census built up on HSB galaxies. Our representative sample of six LSB
galaxies {cz 2700 km/s} are selected such, that a large system of
globular clusters is expected. Globular clusters will constrain phases
of LSB galaxy formation and evolution that can currently not be probed
by other means. HST/ACS imaging is the only facility capable of studying
the globular cluster systems of LSB galaxies given their distance and
relative scarcity.

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.

ACS/WFC 10618

The Light Echoes around V838 Monocerotis: MHD in 3 Dimensions,
Circumstellar Mapping, and Dust

V838 Monocerotis, which burst upon the astronomical scene in early 2002,
is a completely unanticipated new object. It underwent a large-amplitude
and very luminous outburst, during which its spectrum remained that of
an extremely cool supergiant. A rapidly evolving set of light echoes
around V838 Mon was discovered soon after the outburst, and quickly
became the most spectacular display of the phenomenon ever seen. The
light echoes, which were imaged by us with HST during 2002, provide the
means to accomplish four unique types of measurements based on continued
HST imaging during the event: {1} Study effects of MHD turbulence at
high resolution and in 3 dimensions; {2} Construct the first unambiguous
and fully 3-D map of a circumstellar dust envelope in the Milky Way; {3}
Study dust physics in a unique setting where the spectrum and light
curve of the illumination, and the scattering angle, are unambiguously
known; and {4} Determine the distance to V838 Mon through two
independent direct geometric techniques {polarimetry and angular
expansion rates}. Because of the extreme rarity of light echoes, this is
almost certainly the only opportunity to achieve such results during the
lifetime of HST. We propose a campaign during Cycle 14 of imaging the
echoes every 8 days for a total of 6 epochs, in order to fully map a
thin slab through the dust shell and achieve the other goals listed
above.

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.

WFPC2 10359

WFPC2 CYCLE 13 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: (None)

COMPLETED OPS NOTES: (None)


SIGNIFICANT EVENTS: (None)


 




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