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09 Apr 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT # 3337

PERIOD COVERED: DOY 98

Part 1 of 2

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.

WF/PC-2 9046

Black Holes and Bars: A Recipe for Making Bulges?.

The WF/PC-2 was used to obtain multi-color images and (eventually)
STIS emission line spectroscopy of the nuclear regions of 6 edge-on
barred spiral galaxies spanning a range of bulge morphologies and bar
strengths. The goal is to quantify the amount of vertical heating in
the nuclei, and to test whether or not bars are indeed destroyed and
create a bulge if enough mass is accumulated in their centers.

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.

ACS 9363

Ultra Low Surface Brightness Galaxies

Magnitudes fainter than any previously known in that cluster or even
in the Local Group. ACS images of three of these should resolve stars
at the giant branch tip, and allow us to determine distances, mean
metal abundance of the stars, and rough ages. Confirmation of the
nature of these galaxies will provide evidence that dark matter halos
are pervasive in the universe, extending to galaxies with stellar
densities 6 times lower than currently known. These resolved stars
would be the most distant yet observed accurately by HST. 

ACS 9480

Cosmic Shear With ACS Pure Parallels

Small distortions in the shapes of background galaxies by foreground
mass provide a powerful method of directly measuring the amount and
distribution of dark matter. Several groups have recently detected
this weak lensing by large-scale structure, also called cosmic shear.
The high resolution and sensitivity of HST/ACS provide a unique
opportunity to measure cosmic shear accurately on small scales. Using
260 parallel orbits in Sloan textiti {F775W} we will measure for the
first time: beginlistosetlength sep0cm setlengthemsep0cm setlength
opsep0cm em the cosmic shear variance on scales <0.7 arcmin, em the
skewness of the shear distribution, and em the magnification effect.
endlist Our measurements will determine the amplitude of the mass
power spectrum sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20,
and the mass density Omega_m with s/n=4. They will be done at small
angular scales where non-linear effects dominate the power spectrum,
providing a test of the gravitational instability paradigm for
structure formation. Measurements on these scales are not possible
from the ground, because of the systematic effects induced by PSF
smearing from seeing. Having many independent lines of sight reduces
the uncertainty due to cosmic variance, making parallel observations
ideal. 

NICMOS 9484

The NICMOS Parallel Observing Program

We propose to manage the default set of pure parallels with NICMOS.
Our experience with both our GO NICMOS parallel program and the
public parallel NICMOS programs in cycle 7 prepared us to make
optimal use of the parallel opportunities. The NICMOS G141 grism
remains the most powerful survey tool for HAlpha emission-line
galaxies at cosmologically interesting redshifts. It is particularly
well suited to addressing two key uncertainties regarding the global
history of star formation: the peak rate of star formation in the
relatively unexplored but critical 1<= z <= 2 epoch, and the amount
of star formation missing from UV continuum-based estimates due to
high extinction. Our proposed deep G141 exposures will increase the
sample of known HAlpha emission- line objects at z ~ 1.3 by roughly
an order of magnitude. We will also obtain a mix of F110W and F160W
images along random sight-lines to examine the space density and
morphologies of the reddest galaxies. The nature of the extremely
red galaxies remains unclear and our program of imaging and grism
spectroscopy provides unique information regarding both the incidence
of obscured star bursts and the build up of stellar mass at
intermediate redshifts. In addition to carrying out the parallel
program we will populate a public database with calibrated spectra
and images, and provide limited ground- based optical and near-IR
data for the deepest parallel fields.

WFPC2 9594

WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt2/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot
pixels 

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