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Daily #4069



 
 
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Old March 28th 06, 05:22 PM posted to sci.astro.hubble
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Default Daily #4069

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT #4069

PERIOD COVERED: UT March 13, 2006 (DOY 072)

OBSERVATIONS SCHEDULED

ACS/HRC 10114

Lyman_alpha FUV observations of the Sun in time and effects on
planetary atmospheres

The chromospheric H I Ly_alpha 1215.6 feature is the dominant source
of short-wave emission in the Sun and solar-type stars, contributing
about 80-90% of the total FUV flux and 30-60% of the total flux
between 1 and 1500 A. Also, this important chromospheric line is the
major cooling channel for cool star atmospheres. Accurate Ly_alpha
fluxes are the only missing element of our ongoing "Sun in Time"
program. This program studies a sample of single G0-5 V stars with
well-known physical properties that serve as proxies for the Sun {and
solar-mass stars} over their main sequence lifetimes. One of the major
goals of the program is the determination of the spectral irradiance
of the early Sun. Our analyses indicate that the strong XUV emissions
of the young Sun have played a crucial role in the developing
planetary system. In particular, the expected strong Ly_alpha line
flux may have greatly influenced the photoionization, photochemical
evolution and possible erosion of planetary atmospheres, as well as
played a role in the origin and development of life on Earth. The "Sun
in Time" data can also be applied to investigate the atmospheric loss
of exoplanets around solar-type stars resulting from XUV heating,
which can eventually lead to the evaporation of "hot Jupiters". We
propose to determine accurate FUV and Ly-alpha fluxes and irradiances
for 4 representative solar proxies with ages from 130 Myr to 6.7 Gyr.
The proposed study is of capital importance in reconstructing the
evolutionary histories of exoplanets already known and additional
planets that missions such as COROT, Kepler, SIM, and Darwin/TPF will
discover in the coming years.

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 10606

Ultraviolet Snapshots of 3CR Radio Galaxies

Radio galaxies are an important class of extragalactic objects: they
are one of the most energetic astrophysical phenomena and they provide
an exceptional probe of the evolving Universe, lying typically in high
density regions but well-represented across a wide redshift range. In
earlier Cycles we carried out extensive HST observations of the 3CR
sources in order to acquire a complete and quantitative inventory of
the structure, contents and evolution of these important objects.
Amongst the results, we discovered new optical jets, dust lanes,
face-on disks with optical jets, and revealed point-like nuclei whose
properties support FR-I/BL Lac unified schemes. Here, we propose to
obtain ACS NUV images of 3CR sources with z0.3 as a major enhancement
to an already superb dataset. We aim to reveal dust in galaxies,
regions of star and star cluster formation frequently associated with
dust and establish the physical characteristics of the dust itself. We
will measure frequency and spectral energy distributions of point-like
nuclei, seek spectral turnovers in known synchrotron jets and find new
jets. We will strongly test unified AGN schemes and merge these data
with existing X-ray to radio observations for significant numbers of
both FR-I and FR-II sources. The resulting database will be an
incredibly valuable resource to the astronomical community for years
to come.

ACS/HRC 10627

A Snapshot Survey of Post-AGB Objects and Proto-Planetary Nebulae

We propose an ACS/HRC snapshot survey of 50 post-AGB sources, objects
which have evolved from the AGB but may or may not become planetary
nebulae {PNe}. This survey will complement existing HST images of
proto-planetary nebulae {PPNe} and PNe in addressing circumstellar
envelope morphology as a function of: 1} the progenitor star mass; 2}
the chemical composition; and 3} evolutionary stage. We will connect
the observed diversity of nebualar shapes with the main physical and
chemical conditions characterizing post-AGB objects, to identify the
mechanism that breaks the symmetry of AGB mass loss. To our knowledge,
no previous HST projects have been specifically designed to address
this issue. From our database of 360 post-AGB candidates, we have
selected approximately 50 targets, none of which have been or are
being observed with HST, to sample different central star masses,
chemical compositions, and evolutionary stages, uniformly across the
sky. These new data will also provide important constraints to a
quantitative analysis of Spitzer Space Telescope {SST} observations
planned for a similar sample of objects. We will model the HST images
and SST spectra using our axisymmetric dust code 2-Dust, to derive
dust density distributions, pole to equator density ratios, dust shell
masses, inclination angles as well as dust composition.

ACS/HRC 10752

Cycle 14 Focus Monitor

The focus of HST is measured primarily with ACS/HRC over full CVZ
orbits to obtain accurate mean focus values via a well sampled
breathing curve. Coma and astigmatism are also determined from the
same data in order to further understand orbital effects on image
quality and optical alignments. To monitor the stability of ACS to
WFPC2 relative focii, we've carried over from previous focus monitor
programs parallel observations taken with the two cameras at suitable
orientations of previously observed targets, and interspersed them
with the HRC CVZ visits.

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 10775

An ACS Survey of Galactic Globular Clusters

We propose to conduct an ACS/WFC imaging survey of Galactic globular
clusters. We will construct the most extensive and deepest set of
photometry and astrometry to-date for these systems reaching a main
sequence mass of ~0.2 solar mass with S/N = 10. We will combine these
data with archival WFPC2 and STIS images to determine proper motions
for the stars in our fields. The resultant cleaned cluster CMDs will
allow us to study a variety of scientific questions. These include
[but are not limited to] 1} the determination of cluster ages and
distances 2} the construction of main sequence mass functions and the
issue of mass segregation 3} the internal motions and dynamical
evolution of globular clusters, and 4} absolute cluster motions,
orbits, and the Milky Way gravitational potential. We anticipate that
the unique resource provided by the proposed treasury archive will
play a central role in the field of globular cluster studies for
decades, with a stature comparable to that of the Hubble Deep Field
for high redshift studies.

WFPC2 10744

WFPC2 Cycle 14 Decontaminations and Associated Observations

This proposal is for the WFPC2 decons. Also included are instrument
monitors tied to decons: photometric stability check, focus monitor,
pre- and post-decon internals {bias, intflats, kspots, & darks}, UV
throughput check, VISFLAT sweep, and internal UV flat check.

WFPC2 10778

WFPC2 WF4 Supplemental Darks

An anomaly has been found in images from the WF4 CCD in WFPC2. The WF4
CCD bias level appears to have become unstable, resulting in sporadic
images with either low or zero bias level. The other three CCDs {PC1,
WF2, and WF3} appear to be unaffected and continue to operate
properly. These darks are to supplement those in program 10748 to
ensure sufficient dark frames for routine calibration.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10167 - GSacq(1,2,2) failed due to search radius limit exceeded. @
072/15:56:17z

During LOS GSacq(1,2,2) scheduled at 072/15:46:27 failed due to search
radius limit exceeded on FGS 2. ESB message a05 FGS Coarse Track
failed - Search Radius Limit exceeded was received. The map at
15:53:48 showed errors of V1= 1.47, V2=101.06, V3= 0.20 RSS= 101.07

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL FAILURE TIMES
FGS GSacq 09 08 (HSTAR #
10167)
FGS REacq 04 04
OBAD with Maneuver 22 22

SIGNIFICANT EVENTS: (None)

 




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