Daily 3875

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 3875

PERIOD COVERED: UT June 6, 2005 (DOY 157)

OBSERVATIONS SCHEDULED

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 10431

A Search for Faint Companions of Altair

We propose to use the innovative new technique of spectral
deconvolution {Sparks & Ford 2002} to search for very faint
companions, possibly extrasolar planets shining by reflected light,
around Altair, the nearest bright, single star to the Sun. The
technique offers a Poisson-limited detection capability that brings
Jovian-class planets into the realm of feasibility for a select few
stars. We turn the wavelength dependence of the coronagraphic PSF to
advantage and use it to eliminate stray light from the host star. As
part of the detection process, we obtain a spectrum over the
wavelength range, 750 nm to 1 micron, with 9% resolution. The search
will be orders of magnitude more sensitive than all previous efforts
and should take us to within about an order of magnitude of the Jovian
luminosity flux limit.

ACS/HRC/WFC 10389

ACS CCDs daily monitor - Cycle 13 - Part 2

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 program will be
for the entire lifetime of ACS.

ACS/WFC/NIC2 10189

PANS-Probing Acceleration Now with Supernovae

Type Ia supernovae {SNe Ia} provide the most direct evidence for an
accelerating Universe, a result widely attributed to dark energy.
Using HST in Cycle 11 we extended the Hubble diagram with 6 of the 7
highest-redshift SNe Ia known, all at z1.25, providing conclusive
evidence of an earlier epoch of cosmic deceleration. The full sample
of 16 new SNe Ia match the cosmic concordance model and are
inconsistent with a simple model of evolution or dust as alternatives
to dark energy. Understanding dark energy may be the biggest current
challenge to cosmology and particle physics. To understand the nature
of dark energy, we seek to measure its two most fundamental
properties: its evolution {i.e., dw/dz}, and its recent equation of
state {i.e., w{z=0}}. SNe Ia at z1, beyond the reach of the ground
but squarely within the reach of HST with ACS, are crucial to break
the degeneracy in the measurements of these two basic aspects of dark
energy. The SNe Ia we have discovered and measured with HST in Cycle
11, now double the precision of our knowledge of both properties. Here
we propose to quadruple the sample of SNe Ia at z1 in the next two
cycles, complementing on-going surveys from the ground at z1, and
again doubling the precision of dark energy constraints. Should the
current best fit model prove to be the correct one, the precision
expected from the current proposal will suffice to rule out a
cosmological constant at the 99% confidence level. Whatever the
result, these objects will provide the basis with which to extend our
empirical knowledge of this newly discovered and dominant component of
the Universe, and will remain one of the most significant legacies of
HST. In addition, our survey and follow-up data will greatly enhance
the value of the archival data within the target Treasury fields for
galaxy studies.

FGS 10106

An Astrometric Calibration of the Cepheid Period-Luminosity Relation

We propose to measure the parallaxes of 10 Galactic Cepheid variables.
When these parallaxes {with 1-sigma precisions of 10% or better} are
added to our recent HST FGS parallax determination of delta Cep
{Benedict et al 2002}, we anticipate determining the Period-Luminosity
relation zero point with a 0.03 mag precision. In addition to
permitting the test of assumptions that enter into other Cepheid
distance determination techniques, this calibration will reintroduce
Galactic Cepheids as a fundamental step in the extragalactic distance
scale ladder. A Period-Luminosity relation derived from solar
metallicity Cepheids can be applied directly to extragalactic solar
metallicity Cepheids, removing the need to bridge with the Large
Magellanic Cloud and its associated metallicity complications.

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.

NIC2 10428

The colours of QSO host galaxies at z=2 and the evolution of their
stellar masses

We propose to use NICMOS imaging to measure the rest-frame optical/UV
colours of a complete sample of 10 QSO host galaxies at redshifts
between z=1.5 and z=2. From our cycle 11 HST observations {the GEMS
project} we know that QSO host galaxies at redshifts of z~1 show blue
colors despite having early-type morphologies. This is in excellent
agreement with recent SDSS results on low-z AGN hosts, suggesting that
QSO-type activity in galaxies correlates strongly with the presence of
a young stellar population. Our proposed NICMOS observations will
allow us to test the validity of this hypothesis out to z~2, by
relating the observed QSO host colours to those of normal galaxies at
similar redshifts taken from GOODS. We have already established within
GEMS that the QSO hosts in our sample possess substantial UV
luminosities, most likely originating from young stars. Knowing
rest-frame colors, we can estimate stellar ages and stellar masses.
For the first time will it be possible to determine the evolution of
stellar masses in QSO host galaxies from z=2, the epoch of maximum QSO
activity, to the present. Our results will shed light on the relation
between nuclear activity and the star formation history of galaxies,
and how these processes may jointly drive the cosmic evolution of QSOs
and galaxies.

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)


SCHEDULED SUCCESSFUL FAILURE TIMES
FGS Gsacq 05 05
FGS Reacq 10 10
FHST Update 09 09
LOSS of LOCK


SIGNIFICANT EVENTS: (None)