Status Report

NASA Hubble Space Telescope Daily Report # 3393

By SpaceRef Editor
June 28, 2003
Filed under , ,






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.


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 parameterized 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 Imaging and STIS Spectroscopy of Binary Brown Dwarfs

We have compiled a sample of 9 spatially resolved binary brown dwarfs
{18 objects}, and now propose ACS imaging and STIS spectroscopic
follow-up observations. While theoretical models on the interplay of
chemical and physical processes governing brown dwarf atmospheres have
reached a high level of sophistication, interpretation of
observational data remains difficult. As brown dwarfs never stabilize
themselves on the hydrogen main sequence, there is always an ambiguity
between the temperature or luminosity of any brown dwarf and its mass
or age. The individual components of brown dwarf binaries, however,
are expected to be coeval and have the same underlying chemical
composition. This provides crucial constraints on any model, thus
greatly reducing the number of the free parameters. The aim is to
obtain photometric and spectroscopic data to probe the physical and
chemical properties of the brown dwarf atmospheres, as well as second
epoch astrometric data to characterize th e orbital motion. The study
will provide important feedback on theoretical model atmospheres and
evolutionary tracks for brown dwarfs. As such, it will be an important
step towards a better understanding of objects with spectral
properties intermediate between those of giant planets and late-type

ACS 9470

Deep Lyman alpha images of starburst galaxies

We propose a pilot study to obtain deep ACS Ly-alpha images of a
carefully selected sample of local starburst galaxies. Ly-alpha
imaging of such objects has become feasible with ACS. These
observations will bring unprecedented insight into the processes
regulating the luminosity of the cosmologically important Ly-alpha
line. Our targets cover the full range of observed Ly-alpha
properties. They have been chosen to investigate the effects of dust,
the starburst luminosity, and outflows within the ISM. The sample is
optimized for a most favorable trade-off between the relevant
parameter space and the minimum number of orbits. We can build on this
pilot study for a much larger follow-up survey in a later cycle. Deep
H Alpha and H Beta high-resolution images from the ground will allow
us to quantify the Ly-alpha emission {or its lack} and its attenuation
as a function of the local dust content. The H Alpha emission at a
given location will constrain the intrinsic intensity of the expected
Ly-alpha emission. A non-detection will allow us to quantify the
fraction of Ly- alpha photons destroyed within the neutral gas, and to
correlate this fraction with the properties of the neutral gas and
dust. Since Ly-alpha emitters are used to identify and study galaxies
at redshift 3-6, our study will document the circumstances when a
star–forming galaxy shows Ly-alpha emission. This will be an
important first step towards an empirical calibration of the relation
between Ly-alpha and the star–formation rate.


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.


Completing A Near-Infrared Search for Very Low Mass Companions to
Stars within 10 pc of the Sun

Most stars are fainter and less massive than the Sun. Nevertheless,
our knowledge of very low mass {VLM} red dwarfs and their brown dwarf
cousins is quite limited. Unknown are the true luminosity function
{LF}, multiplicity fraction, mass function, and mass-luminosity
relation for red and brown dwarfs, though they dominate the Galaxy in
both numbers and total mass. The best way to constrain these relations
is a search for faint companions to nearby stars. Such a search has
several advantages over field surveys, including greater sensitivity
to VLM objects and the availability of precise parallaxes from which
luminosities and masses can be derived. We propose to complete our
four-filter NICMOS snapshot search for companions to stars within 10
pc. With a 10 sigma detection limit of M_J ~ 20 at 10 pc, we can
detect companions between 10 and 100 AU that are at least 9 mag
fainter than the empirical end of the main sequence and at least 6.5
mag fainter than the brown dwarf Gl 229B. When completed, our search
will be the largest, most sensitive, volume-limited search for VLM
companions ever undertaken. Our four-filter search will permit
unambiguous identification of VLM-companion candidates for follow-up
observation. Together with IR speckle and deep imaging surveys, our
program will firmly establish the LF for VLM companions at separations
of 1-1000 AU and the multiplicity fraction of all stars within 10 pc.

WFPC2 9595


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

STIS 9606

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS 9608

CCD Bias Monitor – Part 2

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

STIS 9615

Cycle 11 MAMA Dark Monitor

This test performs the routine monitoring of the MAMA detector dark
noise. This proposal will provide the primary means of checking on
health of the MAMA detectors systems through frequent monitoring of
the background count rate. The purpose is to look for evidence of
change in dark indicative of detector problem developing.

ACS 9654

ACS photometric Stability

A spectrophotometric standard star {GRW+705824} is observed through
all ACS filters once to assess the sensitivity of the instrument. The
star is placed at the centre of the aperture, and two images are taken
through each filter. This programme is based on proposal 9020 designed
for SMOV and on programme 9563 from the interim period. All the SBC
filters {except Lyman alpha F122M} and all UV filters of the HRC are
tested as part of other programmes and are not listed here. As regards
ramp filters, only one central wavelength is tested per filter. The
exposure times have been selected to reach, on average, SNR~350 in the
central pixel for broad band filters.

ACS 9674

CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
development of hot pixels and test for any source of noise in ACS CCD
detectors. This programme will be executed once a day for the entire
lifetime of ACS.

STIS 9708

STIS Pure Parallel Imaging Program: Cycle 11

This is the default archival pure parallel program for STIS during cycle

WFPC2 9709

POMS Test Proposal: WFII parallel archive proposal

This is the generic target version of the WFPC2 Archival Pure Parallel
program. The program will be used to take parallel images of random
areas of the sky, following the recommendations of the 2002 Parallels
Working Group.

STIS 9783

The Ages of Nuclear Star Clusters in Early-type Spiral Galaxies

We propose to obtain STIS G430L spectra of the previously identified
nuclear star cluster in a sample of 16 spiral galaxies of early to
intermediate Hubble type. HST’s spatial resolution is required to
separate the nuclear cluster from the underlying galaxy bulge.
Analysis of the spectra with population synthesis methods will reveal
the cluster ages. We will use the age distribution to constrain the
duty cycle of nuclear cluster formation. Comparison of the results to
those for a larger sample of nuclear clusters in late-type, bulgeless
galaxies will allow us to investigate possible differences between the
formation mechanisms of nuclear clusters in early and late Hubble
types. Such differences might be expected because galaxy bulges show a
dichotomy: in late Hubble types, the surface brightness profiles are
best described by an exponential, while they follow a de Vaucouleurs
law in earlier types. Although the reason for this dichotomy is still
unknown, it is plausible that galaxy bulges have different formation
mechanisms at the two ends of the Hubble sequence. We know that {1}
nuclear cluster formation is linked to the funneling of gas towards
the nucleus via gravitational torques from stellar bars, {2} a nuclear
mass concentration can make bars unstable, and {3} unstable bars can
form bulges. Therefore, the age distribution of nuclear star clusters
contains important clues to the evolution of galaxy centers and
promises new insight into the origin of the Hubble sequence.

FGS 9879

An Astrometric Calibration of the Cepheid Period-Luminosity Relation

We propose to measure the parallaxes of 10 Galactic Cepheid variables.
There is no other instrument on or off the earth that can consistently
deliver HST FGS level of precision for critical parallaxes. When these
parallaxes {with 1-sigma precisions of 10% or better} are added to our
recent HST FGS parallax determination of delta Cep {Benedict et al
2002}, we anticipate determining the Period-Luminosity relation zero
point with a 0.03 mag precision. In addition to permitting the test of
assumptions that enter into other Cepheid distance determination
techniques, this calibration will reintroduce Galactic Cepheids as a
fundamental step in the extragalactic distance scale ladder. A
Period-Luminosity relation derived from solar metallicity Cepheids can
be applied directly to extragalactic solar metallicity Cepheids,
removing the need to bridge with the Large Magellanic Cloud and its
associated metallicity complications.

ACS 9984

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


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be

HSTAR 9063: Minus Wing Panel Temperature (B_WPANLT) flagged OOL
yellow low (-81.2765 ?C) for 11 samples @ 177/19:04:57Z. Limit is
80.000 ?C. Limit violation occurred at the end of Orbit Night. Back
in bounds @ 177/19:06:03Z. Under investigation.

16995-2 MA/GN Mode Recorder Dump Test @ 177/16:09:50z

1115-0 CCC IP CONFIG Connections @ 177/11:23z

                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq              10                        10
FGS REacq              05                         05
FHST Update            24                         24


Successfully completed MA/GN Mode Recorder Dump @ 177/16:09:50Z (OR
16995-2 with attached script and COP 5.14). An SSR science data
playback was executed via the MA Transponder in GN Mode. PACOR-A
reported receipt of the science data.

HST Checkout of HSTUPS to ANCC scheduled 178/14:30Z – 19:00Z with WSC
TC, GDOC, HITT, STScI, and Sys_Admin. The purpose of this testing is
to verify HSTUPS Release 14, Version 4 software capability to
interface with the Ancillary Network Control Center (ANCC).

SpaceRef staff editor.