Status Report

NASA Hubble Space Telescope Daily Report # 3808

By SpaceRef Editor
March 3, 2005
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NASA Hubble Space Telescope Daily Report # 3808

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT       # 3808



ACS/HRC 10137

Cluster Archeology: The Origin of Ultra-compact Dwarf Galaxies

Ultra-compact dwarf {UCD} galaxies are a new type of galaxy we have
discovered in the central regions of the Fornax and Virgo galaxy
clusters. Our most recent observations in the Fornax Cluster show that
UCDs outnumber normal galaxies in the centre of that cluster. Here we
propose snapshot imaging of UCDs in the Fornax and Virgo clusters to
test theories of how these fascinating objects formed. In particular
we wish to image Virgo cluster UCDs for which we have ground-based
Keck spectroscopy to test predictions that they formed more recently
than the Fornax UCDs.

ACS/HRC 10198

Probing the Dynamics of the Galactic Bar through the Kinematics of
Microlensed Stars

The observed optical depths to microlensing of stars in the Galactic
bulge are difficult to reconcile with our present understanding of
Galactic dynamics. The main source of uncertainty in those comparisons
is now shifting from microlensing measurements to the dynamical models
of the Galactic bar. We propose to constrain the Galactic bar models
with proper motion observations of Bulge stars that underwent
microlensing by determining both the kinematic identity of the
microlensed sources and the importance of streaming motions. The
lensed stars are typically farther than randomly selected stars.
Therefore, our proper motion determinations for 36 targeted MACHO
events will provide valuable constraints on the dynamics of bulge
stars as a function of distance. The first epoch data for our proposed
events is already available in the HST archive so the project can be
completed within a single HST cycle. The exceptional spatial
resolution of HST is essential for completion of the project.
Constraints on the total mass in the bulge will ultimately lead to the
determination of the amount of dark matter in inner Galaxy.

ACS/HRC 10255

A Never Before Explored Phase Space: Resolving Close White Dwarf / Red
Dwarf Binaries

We propose an ACS Snapshot imaging survey to resolve a well-defined
sample of highly probable white dwarf plus red dwarf close binaries.
These candidates were selected from a search for white dwarfs with
infrared excess from the 2MASS database. They represent unresolved
systems {separations less than approximately 2″ in the 2MASS images}
and are distributed over the whole sky. Our HST+ACS observations will
be sensitive to a separation range {1-20 AU} never before probed by
any means. The proposed study will be the first empirical test of
binary star parameters in the post-AGB phase, and cannot be
accomplished from the ground. By resolving as few as 20 of our ~100
targets with HST, we will be able to characterize the distribution of
orbital semi- major axes and secondary star masses.

ACS/HRC 10375

Stability of the ACS CCD: Flat fielding, Photometry, Geometry

This program will verify that the low frequency flat fielding, the
photometry, and the geometric distortion are stable in time and across
the field of view of the CCD detectors. A moderately crowded stellar
field, located ~6′ West of the center of the cluster 47 Tuc, is
observed every three months with the WFC and HRC using the full suite
of broad and narrow band filters. The same field has been observed
during SMOV to derive low frequency corrections to the ground flats
and to create a master catalogue of positions and magnitudes from
dithered observations of the cluster. In Cycles 11-12, this field was
observed again using single pointings at various roll angles. The
positions and magnitudes of objects are used to monitor local and
large scale variations in the plate scale and the sensitivity of the
detectors. The Cycle 13 program will continue to monitor these effects
and will derive an independent measure of the detector CTE.


ACS CCDs daily monitor- cycle 13 – part 1

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.


The COSMOS 2-Degree ACS Survey

We will undertake a 2 square degree imaging survey {Cosmic Evolution
Survey — COSMOS} with ACS in the I {F814W} band of the VIMOS
equatorial field. This wide field survey is essential to understand
the interplay between Large Scale Structure {LSS} evolution and the
formation of galaxies, dark matter and AGNs and is the one region of
parameter space completely unexplored at present by HST. The
equatorial field was selected for its accessibility to all
ground-based telescopes and low IR background and because it will
eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS
instrument. The imaging will detect over 2 million objects with I> 27
mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and
extremely red galaxies out to z ~ 5. COSMOS is the only HST project
specifically designed to probe the formation and evolution of
structures ranging from galaxies up to Coma-size clusters in the epoch
of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The
size of the largest structures necessitate the 2 degree field. Our
team is committed to the assembly of several public ancillary datasets
including the optical spectra, deep XMM and VLA imaging, ground-based
optical/IR imaging, UV imaging from GALEX and IR data from SIRTF.
Combining the full-spectrum multiwavelength imaging and spectroscopic
coverage with ACS sub-kpc resolution, COSMOS will be Hubble’s ultimate
legacy for understanding the evolution of both the visible and dark

FGS 10386

Long Term Monitoring of FGS1r in Position Mode

It is known from our experience with FGS3, and later with FGS1r, that
an FGS on orbit experiences long term evolution, presumably due to
disorption of water from the instrument’s graphite epoxy composites.
This manifests principally as a change in the plate scale and
secondarily as a change in the geometric distortions. These effects
are well modeled by adjustments to the rhoA and kA parameters which
are used to transform the star selector servo angles into FGS {x, y}
detector space coordinates. By observing the relative positions of
selected stars in a standard cluster at a fixed telescope pointing and
orientation, the evolution of rhoA and kA can be monitored and
calibrated to preserve the astrometric performance of FGS1r.

NIC1/NIC2/NIC3 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

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 10337

The COSMOS 2-Degree ACS Survey NICMOS Parallels

The COSMOS 2-Degree ACS Survey NICMOS Parallels. This program is a
companion to program 10092.

NIC3/WFPC2 10403

Ultraviolet Imaging of the UDF

The Hubble Deep Field North has uninterrupted observations at
wavelengths from Far- UV through NICMOS H-band, but the UDF goes no
bluer than B-band. We propose to complete the UDF coverage with deep
ultraviolet imaging of the Ultra-Deep Field {UDF} with the ACS-SBC in
the Far-UV {1500 Angstrom} and WFPC2 in the Near-UV {F300W}. We will
reach point source limits of ABmag=28.5, a factor of ten fainter than
the GALEX ultradeep surveys. Our dataset will add to the value of the
UDF legacy, and requires the unique capabilities of HST. In the spirit
of the UDF, we submit this proposal in the Treasury category. We
request a modest allocation of observing time for a Treasury program:
62 orbits. We will provide science quality images and photometric
catalogs to enable a range of research topics by the community. The
science goals of the team are to investigate the episode of strong
star formation activity in galaxies out to z=1, through the rest-frame
FUV luminosity function and the internal color structure of galaxies.
Far-UV number counts suggest that moderate redshift {z~0.5} starbursts
are undergoing a single, rapid burst of star-formation. We will
investigate this result by measuring the faint-end slope, alpha, of
the luminosity function. We will measure the star formation properties
of moderate redshift starburst galaxies and compare their morphologies
in the UV, optical, and near-IR. This catalog of starbursts will also
be important to the astronomical community in correlating unobscured
star-formation with the sources detected in the Spitzer Space
Telescope legacy observations of the field. With the high spatial
resolution data, will set strict limits on the flux escaping in
intermediate redshift {1 < z < 2} galaxies at wavelengths below the rest-frame Lyman limit, and thus infer the contribution of star forming galaxies at z~5 to the metagalactic ionizing radiation.

WFPC2 10363

WFPC2 CYCLE 13 Intflat and Visflat Sweeps and Filter Rotation Anomaly

Using intflat observations, this WFPC2 proposal is designed to monitor
the pixel-to-pixel flatfield response and provide a linearity check.
The intflat sequences, to be done once during the year, are similar to
those from the Cycle 12 program 10075. The images will provide a
backup database as well as allow monitoring of the gain ratios. The
sweep is a complete set of internal flats, cycling through both
shutter blades and both gains. The linearity test consists of a series
of intflats in F555W, in each gain and each shutter. As in Cycle 12,
we plan to continue to take extra visflat, intflat, and earthflat
exposures to test the repeatability of filter wheel motions.


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.) None


17390- 0 Genslew for proposal 10114 – slot 4 @ 061/17:33z


1310-0  Adjust Battery Charge and Discharge Buffer Red Limits @ 061/15:15z

                             SCHEDULED     SUCCESSFUL    FAILURE TIMES 
 FGS Gsacq                  11                        11 
 FGS Reacq                   06                        06 
 FHST Update                18                        18 


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