Status Report

NASA Hubble Space Telescope Daily Report #3926

By SpaceRef Editor
August 17, 2005
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT        # 3926

PERIOD COVERED: UT August 17, 2005 (DOY 229)


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 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 10497

Cepheid Calibrations of the Luminosity of Two Reliable Type Ia
Supernovae and a Re- determination of the Hubble Constant

We propose to determine the luminosity of two type Ia supernovae {SNe
Ia}, 1995al in NGC 3021 and SN 2002fk in NGC 1309, by observing
Cepheids in their spiral hosts. Modern CCD photometry yields an
extremely tight Hubble diagram for SNe Ia with a precisely determined
intercept {i.e., Delta H_0/H_0}. Yet, the measurement of the true
Hubble constant via SNe Ia is limited by the calibration derived from
problematic and unreliable SN data. Most of the SNe Ia calibrated by
HST to date are significantly compromised by the systematics of
photographic photometry, high reddening and SN peculiarity, and by the
photometric anomolies associated with WFPC2. The extended reach of ACS
now provides opportunities to more reliably calibrate SNe Ia and H_0.
Our Cepheid calibration of a reliable SN Ia dataset, SN 1994ae, using
ACS in Cycle 11 resulted in a 15% increase in H_0 from the value
derived by the HST SN Ia Calibration Program. Yet, there remains a
terribly small sample of reliable SN Ia data sets on which to base
such a crucial cosmological result. SN 1995al and SN 2002fk are two of
the best observed SNe Ia both with little reddening. They provide two
opportunities to use ACS for placing the calibration of H_0 via SN Ia
on firmer footing and potentially improve its precision.

ACS/WFC/NIC3 10405

Probing the establishment of galaxy morphologies in the best-studied
high-redshift structure

We propose deep ACS I-band imaging of arguably the best-studied
high-redshift proto-cluster environment, a high-contrast structure in
the SSA22 field at z=3.1. Our on-going study of this region has
identified over 400 probable members of this structure across a
16-arcmin-square field, selected through narrow-band Lyman-alpha
emission, Lyman-break photometric criteria and far-infrared/radio
emission. Our proposed high-resolution imaging of galaxies in the
z=3.1 structure and in the nearby field, will provide morphological
information on galaxies over nearly two-orders of magnitude in local
density at this early epoch. This will allow us for the first time to
test whether galaxy morphology is defined at the formation of a galaxy
or reflects processes acting on it during its lifetime.

FGS 10610

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric
elements {perturbation orbit semi-major axis and inclination} of
extra-solar planets orbiting six stars. These companions were
originally detected by radial velocity techniques. We have
demonstrated that FGS astrometry of even a short segment of reflex
motion, when combined with extensive radial velocity information, can
yield useful inclination information {McArthur et al. 2004}, allowing
us to determine companion masses. Extrasolar planet masses assist in
two ongoing research frontiers. First, they provide useful boundary
conditions for models of planetary formation and evolution of
planetary systems. Second, knowing that a star in fact has a plantary
mass companion, increases the value of that system to future
extrasolar planet observation missions such as SIM PlanetQuest, TPF,
and GAIA.

NIC1/NIC2/NIC3 10721

NICMOS dark current tests for newly implemented SPARS sequences

On June 12, 2005, 4 new NICMOS multiaccum sequences {SPARS4, SPARS16,
SPARS32, SPARS128} were implemented. The purpose of this observation
is to measure the dark currents for these new multiaccum sequences for
all three NICMOS detectors.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration – CR Persistence Part 4

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.


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

HSTARS: (None)



                             SCHEDULED     SUCCESSFUL 
 FGS Gsacq                 06                       06 
 FGS Reacq                 09                       09 
 FHST Update              10                       10 


The first visit to the moon to the Apollo 17 target was successful,
providing good quality images in all bands. The observers are pleased
with the results.

SpaceRef staff editor.