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Daily #4045

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Old February 8th 06, 01:26 PM posted to sci.astro.hubble
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Default Daily #4045

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science


PERIOD COVERED: UT February 07, 2006 (DOY 038)


ACS/HRC 10572

Resolving M32's Main Sequence: A Critical Test for Stellar Population

We propose to observe the M32 main-sequence turnoff {MSTO} with deep
ACS/HRC B and V images. Only the superior resolution and blue
sensitivity of ACS/HRC make this possible. M32 is the only elliptical
galaxy close enough to allow direct observation of its MSTO - it is a
vital laboratory for deciphering the stellar populations of all other
elliptical galaxies, which can only be studied by the spectra of their
integrated light, given their greater distances. Major questions about
M32's star formation history remain unanswered. Spectral studies
suggest that M32 underwent a recent burst of star formation 3 to 8
billion years ago; observation of the M32 MSTO will confirm this
directly. In the process, ACS will easily resolve more luminous
components: hot blue stars, luminous, intermediate-age red clump and
AGB stars, and any extended blue horizontal branch. These detailed
CMDs will provide a direct comparison with population synthesis models
for M32, providing a bridge to studies of the integrated light of more
distant elliptical galaxies, a crucial ingredient for understanding
their star formation histories. As M32 is projected against the edge
of the M31 disk, an essential part of our proposal includes deep
observation of an M31 disk field to allow the M32 photometry to be
background corrected. These observations will reveal the star
formation history of M31's outer disk and are thus of interest in
their own right.

ACS/SBC 10507

High resolution imaging of Jupiter's diffuse auroral emissions inside
and outside the main oval during solar

The analysis of HST-STIS FUV images has greatly and quickly advanced
our knowledge of the magnetospheric mechanisms producing the auroral
emissions on the giant planets. However, these studies were limited to
the brightest emissions and very little has been said about the
fainter emissions, mainly because of the lower S/N. We propose to
image the faint auroral emissions on Jupiter which could not be
observed with STIS. We will take full advantage of ACS/SBC's higher
sensitivity to observe the diffuse auroral FUV emissions appearing
poleward and directly equatorward of Jupiter's main auroral oval in
the northern hemisphere. This proposal has the potential to reveal new
magnetosphere-ionosphere coupling mechanisms especially those
involving solar wind interactions with a giant planet.

ACS/WFC 10543

Microlensing in M87 and the Virgo Cluster

Resolving the nature of dark matter is an urgent problem. The results
of the MACHO survey of the Milky Way dark halo toward the LMC indicate
that a significant fraction of the halo consists of stellar mass
objects. The VATT/Columbia survey of M31 finds a similar lens fraction
in the M31 dark halo. We propose a series of observations with ACS
that will provide the most thorough search for microlensing toward
M87, the central elliptical galaxy of the Virgo cluster. This program
is optimized for lenses in the mass range from 0.01 to 1.0 solar
masses. By comparing with archival data, we can detect lenses as
massive as 100 solar masses, such as the remnants of the first stars.
These observations will have at least 15 times more sensitivity to
microlensing than any previous survey, e.g. using WFPC2. This is due
to the factor of 2 larger area, factor of more than 4 more sensitivity
in the I-band, superior pixel scale and longer baseline of
observations. Based on the halo microlensing results in the Milky Way
and M31, we might expect that galaxy collisions and stripping would
populate the overall cluster halo with a large number of stellar mass
objects. This program would determine definitively if such objects
compose the cluster dark matter at the level seen in the Milky Way. A
negative result would indicate that such objects do not populate the
intracluster medium, and may indicate that galaxy harassment is not as
vigorous as expected. We can measure the level of events due to the
M87 halo: this would be the best exploration to date of such a lens
population in an elliptical galaxy. Star-star lensing should also be
detectable. About 20 erupting classical novae will be seen, allowing
to determine the definitive nova rate for this giant elliptical
galaxy. We will determine if our recent HST detection of an M87
globular cluster nova was a fluke, or indicative of a 100x higher rate
of incidence of cataclysmic variables and nova eruptions in globulars
than previously believed. We will examine the populations of variable
stars, and will be able to cleanly separate them from microlensing.

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.


Probing Evolution And Reionization Spectroscopically {PEARS}

While imaging with HST has gone deep enough to probe the highest
redshifts, e.g. the GOODS survey and the Ultra Deep Field,
spectroscopic identifications have not kept up. We propose an ACS
grism survey to get slitless spectra of all sources in a wide survey
region {8 ACS fields} up to z =27.0 magnitude, and an ultradeep field
in the HUDF reaching sources up to z =28 magnitude. The PEARS survey
will: {1} Find and spectrocopically confirm all galaxies between
z=4-7. {2} Probe the reionization epoch by robustly determining the
luminosity function of galaxies and low luminosity AGNs at z = 4 - 6.
With known redshifts, we can get a local measure of star formation and
ionization rate in case reionization is inhomogeneous. {3} Study
galaxy formation and evolution by finding galaxies in a contiguous
redshift range between 4 z 7, and black hole evolution through a
census of low-luminosity AGNs. {4} Get a robust census of galaxies
with old stellar populations at 1 z 2.5, invaluable for checking
consistency with heirarchical models of galaxy formation. Fitting
these galaxies' spectra will yield age and metallicity estimates. {5}
Study star-formation and galaxy assembly at its peak at 1 z 2 by
identifying emission lines in star-forming galaxies, old populations
showing the 4000A break, and any combination of the two. {6} Constrain
faint white dwarfs in the Galactic halo and thus measure their
contribution to the dark matter halo. {7} Derive spectro-photometric
redshifts by using the grism spectra along with broadband data. This
will be the deepest unbiased spectroscopy yet, and will enhance the
value of the multiwavelength data in UDF and the GOODS fields to the
astronomical community. To this end we will deliver reduced spectra to
the HST archives.

FGS 10103

FGS Astrometry of a Star Hosting an Extrasolar Planet: The Mass of
Upsilon Andromedae d

We propose observations with HST/FGS to determine the astrometric
elements {perturbation orbit semimajor axis and inclination} produced
by the outermost extra-solar planet orbiting the F8V star Upsilon
Andromedae. These observations will permit us to determine the actual
mass of the planet by providing the presently unknown sin i factor
intrinsic to the radial velocity method which discovered this object.
An inclination, i = 30degrees, within the range of one very low
precision determination using reanalyzed HIPPARCOS intermediate data
products, would produce the observed radial velocity amplitude, K = 66
ms with a companion mass of ~8 M_Jupiter. Such a mass would induce in
Upsilon Andromedae a perturbation semi-major axis, Alpha = 0arcs0012,
easily within the reach of HST/FGS fringe tracking astrometry. The
proposed observations will yield a planetary mass, rather than, as
previous investigations have done, only suggest a planetary mass


NICMOS Post-SAA calibration - CR Persistence Part 2

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 10745


This calibration proposal is the Cycle 14 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{both gain 7 and gain 15 -- to test stability of gains and bias
levels}, a test for quantum efficiency in the CCDs, and a monitor for
possible buildup of contaminants on the CCD windows. These also
provide raw data for generating annual super-bias reference files for
the calibration pipeline.


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


10120 - GSAcq(2,1,2) results in finelock backup (1,0,1) due to scan
step limit exceeded on FGS-2 038/09:45:57z

The GSAcq(2,1,2) scheduled at 038/09:45:57 - 09:53:34 Z resulted in
finelock backup (1,0,1) using FGS-1, due to scan step limit exceeded
on FGS-2. Prior OBAD2 at 038/09:41:27 had total attitude correction
(RSS) value of 6.65 arcseconds.

10121 - FGS1 enters CT twice @ 034/06:55z

OTA SE review of PTAS processing data revealed that FGS1 entered CT
twice before achieving CT-DV during GSAcq(1,2,2) scheduled for
2006/034 06:52:54.

17597-2 - FHST Stuck-on-Bottom Macro Execution @ 038/22:44z


GSacq 10 10
REacq 05 05
OBAD with Maneuver 24 24


FHST Stuck on Bottom Macro Execution

FHST 3 was observed to be Stuck on Bottom briefly during a 1st OBAD at
~ 038/22:20. Before the OBAD completed, FHST 3 released from its SOB
condition and achieved Valid Rate on a pair of stars with catalog
magnitudes of 5.8 and 6.87. This situation presented an opportunity to
test the Stuck on Bottom macro, if FHST 3 could be commanded to leave
the stars it was tracking and (perhaps) stick at the bottom again.
Since all three FHSTs were available (FHST 1 was the rate controller),
there was little risk to the forthcoming acquisition involved in
breaking FHST 3 off of its stars. The SOB macro commanding for FHST 3
was sent at 038/22:43, and again at 038/22:44. Reviewing telemetry
from the commanding events, the FHST 3 star magnitude threshold is
seen to change from 6th to 5th; however, the combined brightness of
the stars that FHST 3 was tracking resulted in an apparent star
magnitude between 4.97 and 5.06. Therefore FHST 3 did not leave the
stars. Unfortunately this provides us no information concerning the
effectiveness of the SOB macro in clearing SOB events.


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