This Echo is READ ONLY !   NO Un-Authorized Messages Please!
 ~~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

15 Apr 2003

HUBBLE SPACE TELESCOPE

DAILY REPORT #3341

PERIOD COVERED:  DOY 104

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. 

ACS 9352

The Deceleration Test from Treasury Type Ia Supernovae at Redshifts
1.2 to 1.6 extraordinary result that needs a rigorous test. The case
for cosmic acceleration rests on the observation that SNe Ia at
z ~ 0.5 are ~ 0.25 mag fainter than they would be in a universe
without acceleration. A powerful and straightforward way to assess
the reliability of the SN Ia measurement and the conceptual framework
of its interpretation is to look for cosmic deceleration at z >= 1.
This would be a clear signature of a mixed dark-matter and
dark-energy universe. Systematic errors in the SN Ia result
attributed to grey dust or cosmic evolution of the SN Ia peak
luminosity would not show this change of sign. We have demonstrated
proof of this concept with a single SN Ia, SN 1997ff at z = 1.7,
found and followed by HST. The results suggest an early epoch of
deceleration, but this is too important a conclusion to rest on just
one object. Here we propose to use HST for observations of six SNe Ia
in the range 1.2 <= z <= 1.6, that will be discovered as a byproduct
from proposed Treasury programs for high-latitude ACS surveys. Six
objects will provide a much firmer foundation for a conclusion that
touches on important questions of fundamental physics. 

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/STIS CCD 9405

The Origin of Gamma-Ray Bursts

The rapid and accurate localization of gamma-ray bursts {GRBs}
promised by a working HETE-2 during the coming year may well
revolutionize our ability to study these enigmatic, highly luminous
transients. We propose a program of HST and Chandra observations to
capitalize on this extraordinary opportunity. We will perform some of
the most stringent tests yet of the standard model, in which GRBs
represent collimated relativistic outflows from collapsing massive
stars. NICMOS imaging and STIS CCD spectroscopy will detect broad
atomic features of supernovae underlying GRB optical transients, at
luminosities more than three times fainter than SN 1998bw. UV,
optical, and X-ray spectroscopy will be used to study the local ISM
around the GRB. Chandra spectroscopy will investigate whether the GRB
X-ray lines are from metals freshly ripped from the stellar core by
the GRB. HST and CTIO infra-red imaging of the GRBs and their hosts
will be used to determine whether `dark' bursts are the product of
unusually strong local extinction; imaging studies may for the first
time locate the hosts of `short' GRBs. Our early polarimetry and
late-time broadband imaging will further test physical models of the
relativistic blast wave that produces the bright GRB afterglow, and
will provide unique insight into the influence of the GRB environment
on the afterglow. 

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.

WFPC2 9592

WFPC2 CYCLE 11 Standard Darks

Calibration of the CCD dark current rate, and to monitor and
characterize the evolution of hot pixels. Over an extended period
these data will also provide a monitor of radiation damage to the
CCDs. 

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 

 - Continued -

@Message posted automagically by IMTHINGS POST 1.30
---