Daily #4020

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4020

PERIOD COVERED: UT January 03, 2006 (DOY 003)

OBSERVATIONS SCHEDULED

ACS/HRC 10695

Coronagraphic Search for Disks around Nearby Stars

This is a search for debris disks around nearby G-type stars that have
infrared excesses. The ACS coronagraph will be used with filter F606W.

ACS/WFC 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with
Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful
"dust free" Type Ia supernovae {SNe Ia} dataset than available with
the previous GOODS searches. Moreover, this approach provides a
strikingly more efficient search-and-follow-up that is primarily pre-
scheduled. The resulting dark energy measurements do not share the
major systematic uncertainty at these redshifts, that of the
extinction correction with a prior. By targeting massive galaxy
clusters at z 1 we obtain a five-times higher efficiency in
detection of Type Ia supernovae in ellipticals, providing a
well-understood host galaxy environment. These same deep cluster
images then also yield fundamental calibrations required for future
weak lensing and Sunyaev-Zel'dovich measurements of dark energy, as
well as an entire program of cluster studies. The data will make
possible a factor of two improvement on supernova constraints on dark
energy time variation, and much larger improvement in systematic
uncertainty. They will provide both a cluster dataset and a SN Ia
dataset that will be a longstanding scientific resource.

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 10580

A tip of the red giant branch distance to NGC 4038/39 {The Antennae}

We propose to use ACS to determine a tip of the red giant branch
{TRGB} distance to the merger system archetype NGC4038/39 {"The
Antennae"}. This system is the closest major merger to us, but its
distance remains a point of debate, with proposed values ranging from
14 to 33 Mpc. Our previous HST/WFPC2 V, I band observation targeted
the star forming {SF} regions near the tip of the southern tail of
NGC4038. These data revealed a background population of red stars far
from SF regions which we identify as RGB stars. The TRGB was detected
near our completeness limit at about 26.5 mag, suggesting a distance
of 13.8+/-1.7 Mpc, 30% lower than the most accepted distance of 21
Mpc, and less than half the distance of 29 Mpc adopted to characterize
the "ultraluminous X-ray binaries" {UXB} sources discovered in recent
Chandra observations by Fabbiano et al. {2001}. The lower distance has
profound implications for the mass and luminosities of all sources
associated with The Antennae, such as the Tidal Dwarf candidates, the
globular cluster system, and the UXB population. With its greater
sensitivity and higher resolution, ACS can resolve this issue in just
a few orbits. We therefore request seven orbits to obtain V, I band
images of the southern tail of NGC4038/39 to reach 1.6 mag lower than
the TRGB, for our proposed distance modulus. Even if the larger
distance is the correct one, our proposed imaging would still give a
robust distance constraint from the TRGB.

ACS/WFC 10588

The Host Galaxies of Post-Starburst Quasars

We propose to use ACS to conduct a snapshot imaging survey of
post-starburst quasars now being discovered in signficant numbers by
the Sloan Digital Sky Survey. Post-starburst quasars are broad-lined
AGN that also possess Balmer jumps and high-n Balmer absorption lines
indicative of luminous stellar populations on order of 100 Myr old.
These objects, representing a few percent of the z 0.5 quasar
population, may be an evolutionary stage in the transition of
ultraluminous infrared galaxies into normal quasars, or a type of
galaxy interaction that triggers both star formation and nuclear
activity. These sources may also illustrate how black hole mass/bulge
mass correlations arise. Ground-based imaging of individual
poststarburst quasars has revealed merger remnants, binary systems,
and single point sources. Our ACS snapshots will enable us to
determine morphologies and binary structure on sub-arcsecond scales
{surely present in the sample and impossible to do without HST}, as
well as basic host galaxy properties. We will be looking for
relationships among morphology, particularly separation of double
nuclei, the starburst age, the quasar black hole mass and accretion
rate, that will lead to an understanding of the triggering activity
and mutual evolution. This project will bring quantitative data and
statistics to the previously fuzzy and anecdotal topic of the
"AGN-starburst connection" and help test the idea that post-starburst
quasars are an early evolutionary stage of normal quasars.

ACS/WFC/WFPC2 10499

Life Before the Fall: Morphological Evolution of Galaxies in Groups
Prior to Cluster Assembly at z=0.37

We propose to obtain a deep ACS/WFC mosaic of a protocluster comprised
of 4 distinct galaxy groups that are gravitationally bound to each
other at z=0.37. The galaxy groups have a total combined mass
comparable to the Coma cluster and already have twice as many
absorption line galaxies as the field. The SG1120 complex thus
provides an unprecedented opportunity for determining whether
"pre-processing" in the group environment is responsible for the bulk
of observed diffences between galaxies in nearby clusters and those in
the field. High resolution imaging with HST is needed to
morphologically classify the group members and measure their
structural parameters. By combining the early-type fraction and
morphology-density relation in SG1120 with results from our wide-field
spectroscopic survey, we will test whether spectral and morphological
transformation timescales are decoupled on group scales and isolate
the environmental mechanisms responsible for such evolution. We will
also measure the Fundamental Plane and M/L ratios of the early-type
members to constrain their formation epoch and how their stellar
populations have evolved. Observations of the multiple galaxy groups
in SG1120 provide a unique dataset to the community and will aid our
understanding of how galaxies evolve in the still poorly studied group
regime.

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.

WFPC2 10745

WFPC2 CYCLE 14 INTERNAL MONITOR

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.

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)

SCHEDULED SUCCESSFUL
FGS GSacq 09 09
FGS REacq 05 05
OBAD with Maneuver 25 25

SIGNIFICANT EVENTS: (None)