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26 Mar 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT        # 3327

PERIOD COVERED: DOY 84

Part 1 of 3

OBSERVATIONS SCHEDULED

FLIGHT OPERATIONS SUMMARY:

NICMOS 8791

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.

ACS/HRC 9295

Coronagraphic search for disks around nearby stars

HD 163296 is a Herbig Ae star with a circumstellar disk that was
previously imaged using STIS. It is the source of a bipolar jet that
consists of discrete knots, also seen in the STIS images. HD 100546
is a Herbig Be star with a circumstellar disk that was previously
imaged using STIS and NICMOS. The STIS images show disk-like
circumstellar material with a somewhat spiral structure. GG Tauri is
a young binary {0.25" separation} that is surrounded by a
circumbinary disk that appears as an inclined ring with a semi-minor
axis of 1" and a semi-major axis of 1.8". The interior of the disk
has been cleared by tidal forces due to the binary, resulting in the
ring-like appearance. A gap in the ring is seen in HST and
ground-based adaptive optics images. It is likely a shadow cast by
material between the ring and the stars. WFPC2 images have revealed
material within 0.3" of the secondary star that might be dust trapped
at a Lagrangian point {it is too large to be a circumstellar disk}.
Verification of this material is important as it may influence the
illumination of the outer ring. The WFPC2 images failed to detect the
far side of the ring in F555W due to the intrinsic faintness of the
ring at that wavelength {due to increased forward scattering} and PSF
subtraction residuals. The greater sensitivity of the ACS and its
more stable PSF should provide a definite detection of the far side,
providing important constraints on the relationship between
wavelength and the scattering phase, as well as possible reddening of
the ring caused by intervening dust.

STIS/CCD/MA1 9357

Towards a global understanding of accretion physics --, Clues from an
UV spectroscopic survey of cataclysmic variables

Accretion inflows and outflows are fundamental phenomena in a wide
variety of astrophysical environments, such as Young Stellar Objects,
galactic binaries, and AGN. Observationally, cataclysmic variables
{CVs} are particularly well suited for the study of accretion
processes. We propose to carry out a STIS UV spectroscopic snapshot
survey of CVs that fully exploits the diagnostic potential of these
objects for our understanding of accretion physics. This survey will
provide an homogenous database of accretion disc and wind outflow
spectra covering a wide range of mass transfer rates and binary
inclinations. We will analyze these spectra with state-of-the-art
accretion disc model spectra {SYNDISK}, testing our current knowledge
of the accretion disc structure, and, thereby, providing new insight
into the so far not well understood process of viscous dissipation.
We will use our parameterised wind model PYTHON for the analysis of
the radiation driven accretion disc wind spectra, assessing the
fundamental question whether the mass loss rate correlates with the
disc luminosity. In addition, our survey data will identify a number
of systems in which the white dwarf significantly contributes to the
UV flux, permitting an analysis of the impact of mass accretion on
the evolution of these compact stars. This survey will at least
double, if not triple, the number of high-quality accretion disc /
wind outflow / accreting white dwarf spectra, and we waive our
proprietary rights to permit a timely use of this database.

ACS/HRC 9379

Near Ultraviolet Imaging of Seyfert Galaxies: Understanding the
Starburst-AGN Connection

We propose a near-UV snapshot survey of 101 Seyfert galaxies using
ACS/HRC and the filter F330W, a configuration which is optimal to
detect faint star forming regions around their nuclei. These images
will complement optical and near-IR images available in the HST
archive, thus providing a panchromatic atlas of the inner regions of
active galaxies, which we will use to study the starburst-AGN
connection. The main goals of this proposal are: {1} Determine the
frequency of circumnuclear starbursts in Seyferts, down to levels
which cannot be observed from the ground; {2} characterize the
observational {fluxes, colors, structure, sizes} and intrinsic
{luminosities, masses, ages, global star-formation rate} properties
of these clusters; {3} derive the luminosity functions of young star
clusters around the nucleus of Seyferts and compare these results
with those from normal and starburst galaxies to determine their
survival rate close to the AGN; {4} address questions about the
relation between AGNs and starbursts, like the possible connection
between the masses and luminosities of black holes and starbursts,
and the implications for the evolution of the black holes and their
host galaxy bulges. By adding UV images to the existing optical and
near-IR ones, this project will create an extremely valuable database
for astronomers with a broad range of scientific interests, from the
properties of the AGN to the properties of their host galaxies.

 - Continued -

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