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28 April 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT #3350

PERIOD COVERED: DOY 115-117

Part 3 of 5

NICMOS 9386

Infrared Photometry of a Statistically Significant Sample of KBOs

While the discovery rate of Kuiper Belt objects is accelerating, the
physical study of this new region of the solar system has been slowed
by a lack of basic astrophysical data. Photometric observations of
the majority of the more than 400 known KBOs and Centaurs are
rudimentary and incomplete, particularly in the infrared. The
multicolor optical-infrared photometry that exists for a small subset
of KBOs often shows significant discrepancies between observations by
different observers. Their intrinsic faintness puts them at the
practical limits of ground-based systems. In July 2001 we began what
will be the largest uniform sample of optical photometry of KBOs with
a WFPC2 SNAPSHOT program that will perform accurate photometry at V,
R, and I on a sample of up to 150 targets. We seek to greatly enhance
the value of this survey by obtaining J and H photometry on the same
sample using NICMOS. Combined optical and infrared broad band
photometry is a far more powerful tool for physical studies than is
either alone. Our sample includes objects that will be observed at
thermal infrared wavelengths by SIRTF and will be used with those
data to derive the first accurate diameters, albedos, and surface
properties for a large sample of KBOs.

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.

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.

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. 

STIS 9608

CCD Bias Monitor - Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at
gain=1, and 1x1 at gain = 4, to build up high-S/N superbiases and
track the evolution of hot columns. 

STIS 9606

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS 9627

CCD Sensitivity Monitor for Cycle 11

Monitor sensitivity of each CCD grating mode to detect any change due
to contamination or other causes.  Also monitor the STIS focus in an
imaging mode 

 - Continued -

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