02 May 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT # 3354

PERIOD COVERED: DOY 121

Part 1 of 3

OBSERVATIONS SCHEDULED

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/WFC 9351

Determining Hubble's Constant from Observations of Cepheids in the
Host Galaxy of SN Ia 1994ae

We propose to determine the luminosity of the type Ia supernova {SN
Ia} 1994ae by observing Cepheids in the host spiral galaxy NGC 3370.
Modern CCD photometry has yielded an extremely tight Hubble diagram
for SNe Ia with a precisely determined intercept {i.e., Delta H_0/
H_0} 1 measurement of the true Hubble constant is still limited by
the calibration. The HST calibration of all but a few SNe Ia observed
to date is significantly compromised by the systematics of
photographic photometry and host galaxy extinction, as well as by the
photometric uncertainties associated with WFPC2. In contrast, SN
1994ae is one of the very best-observed SNe Ia with CCD photometry.
The exquisite B, V, R, and I light curves are well-sampled beginning
10 days before maximum brightness, and they indicate little
reddening. From our supernova photometry and the current provisional
SN Ia calibration we would find a distance of 30 +/- 2.1 Mpc, well
within the range where ACS can accurately observe Cepheid light
curves and distinguish Cepheids from nonvariable stars. 

SNAP 9356

SNAPSHOT survey of the Planetary Nebulae population of the Galactic
Bulge

The spectacular structures seen in HST images of planetary nebulae
{PNe} are generally accepted as originating from hydrodynamical
interactions between stellar winds: the interacting-stellar wind
model {ISW}. Traditionally, the shaping is thought to occur after the
star becomes hot enough to ionize the PN. But recent HST images
indicate that the shaping may occur earlier, and the newer GISW model
puts the shaping during the pre-planetary nebula evolution. The
relative importance of both models is not known: GISW shaping will
account for some fraction of PNe, but estimates range from 15--100
during the PN phase, especially for the youngest PNe. We here propose
an HST Snapshot survey of compact PNe in the Galactic Bulge, to test
these predictions. The Bulge provides the only PNe population for
which progenitor masses are known and nebular ages can be measured.
In support of these HST measurements we have already measured
velocity fields and emission line fluxes. The survey will give an
unbiased sampling of morphologies, and allow evolutionary sequences
to be determined to test the ISW versus the GISW model. By-products
of the survey will be the determination of nebular masses, diameters
and filling factors. We will also obtain the White Dwarf mass
distribution in the Bulge, and the initial-final mass function for
low-mass stars. 

HST 9382

A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS
QSO MgII-FeII Systems.

We have searched the first public release of SDSS QSO spectra for
low-z {z<1.65} metal absorption lines and found over 200 large rest
equivalent width MgII-FeII systems. Previously, we empirically showed
that such systems are good tracers of large neutral gas columns,
with ~50% being classical damped Lyman alpha {DLA} systems
{N_HI>=2*10^20 cm^-2}. Here we propose to follow up a well-defined
subset of 79 of them to search for DLAs with 0.47 * Origin: SpaceBase(tm) Pt 1 -14.4- Van BC Canada 604-473-9358 (1:153/719.1)

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