Status Report

NASA Hubble Space Telescope Daily Report # 3384 (part 2)

By SpaceRef Editor
June 16, 2003
Filed under , ,

FGS 9348

The Distances to AM CVn stars

We propose to determine the parallaxes and proper motions of the five
brightest of the seven known AM CVn systems using the HST Fine
Guidance Sensors. AM CVn systems are binaries where mass is
transferred from a completely hydrogen-deficient, degenerate mass
donor to a white dwarf primary through a helium accretion disk. A
better understanding of these systems is crucial for a number of
reasons:, to study the late stages of binary evolution, to study the
effect of chemical composition on the physics of accretion discs; , o
to estimate their contribution to the Supernovae Ia rate and , to
estimate their contribution to the gravitational radiation background.
All these studies rely critically on a determination of the distances
to the currently known systems. With brightnesses in the range 13<V<17
and estimated distances <400pc they are ideal targets for the HST-FGS.

FGS1R 9408

Calibrating the Mass-Luminosity Relation at the End of the Main Sequence

We propose to use HST-FGS1R to calibrate the mass-luminosity relation
{MLR} for stars less massive than 0.2 Msun, with special emphasis on
objects near the stellar/brown dwarf border. Our goals are to
determine M_V values to 0.05 magnitude, masses to 5 than double the
number of objects with masses determined to be less than 0.20 Msun.
This program uses the combination of HST-FGS3/FGS1R at optical
wavelengths and ground-based infrared interferometry to examine
nearby, subarcsecond binary systems. The high precision measurements
with HST-FGS3/FGS1R {to 1 mas in the separations} for these faint
targets {V = 10–15} simply cannot be equaled by any ground based
technique. As a result of these measurements, we are deriving high
quality luminosities and masses for the components in the observed
systems, and characterizing their spectral energy distributions from
0.5 to 2.2 Mum. Several of the objects included have M < 0.1 Msun,
placing them at the very end of the stellar main sequence. Three of
the targets are brown dwarf candidates, including the current low mass
record holder, GJ 1245C, with a mass of 0.062 +/- 0.004 Msun. The
payoff of this proposal is high because all 10 of the systems selected
have already been resolved with HST- FGS3/FGS1R during Cycles 5–10
and contain most of the reddest objects for which masses can be


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.


Flats Stability

This calibration proposal is the Cycle 11 NICMOS monthly monitor A
series of camera 1, 2, & 3 flat fields will be obtained to monitor the
health of the cameras.


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.


Photometric Stability

This NICMOS calibration proposal carries out photometric monitoring
observations during cycle 11.


The Host Galaxies of Time Delay Lenses: , An Independent Route to the
Hubble Constant

Because of its importance in setting the distance scale, the time
scale and in estimating cosmological parameters from the CMB,
astronomy needs an estimate of the Hubble constant independent of the
local distance scale and its systematic problems. This can be achieved
using gravitational lenses with time delay measurements given enough
constraints on the gravitational potential of the lens. We will use
deep NICMOS observations of the lensed quasar host galaxies in 7
gravitational lenses with time delay measurements to obtain the
necessary constraints, determine the dark matter distribution and
estimate H_0. Analysis of the existing images and the well-developed
theory for analyzing Einstein ring images of host galaxies suggest the
new data will break the familiar degeneracies between lens mass
distributions and the Hubble constant. We also request 30 ksec Chandra
ACIS images for each of the 2 systems lacking them {B1608+656 and
B1600+434} to measure the mass in nearby or surrounding groups and


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.

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 9606

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS 9973

Intensive Coverage of the Eta Carinae Event in 2003

For a variety of reasons, HST can provide a very special and unique
data set when Eta Car experiences its next spectroscopic event in
mid-2003. Explaining the phenomenon is only part of the motivation.
This star and its ejecta have unique characteristics that make them
important for several branches of astrophysics; and when a
spectroscopic event occurs, it’s like varying the parameters in an
experiment {or rather, set of experiments}. The 2003 event may be the
only chance in the forseeable future to obtain such a data set,
especially with HST. Eta Carinae has extreme parameters; it is
mysterious in surprisingly basic ways; and HST/STIS can gather useful
data on it at a terrific rate. As we explain below, the proposed data
set will be valuable in several independent ways: It will help solve a
specific set of current problems, it will constitute a large and
unique archival data base for both stellar and nebular astrophysics,
and it will be well-suited for educational uses.

STIS 9633

STIS parallel archive proposal – Nearby Galaxies – Imaging and

Using parallel opportunities with STIS which were not allocated by the
TAC, we propose to obtain deep STIS imagery with both the Clear
{50CCD} and Long-Pass {F28X50LP} filters in order to make
color-magnitude diagrams and luminosity functions for nearby galaxies.
For local group galaxies, we also include G750L slitless spectroscopy
to search for e.g., Carbon stars, late M giants and S-type stars. This
survey will be useful to study the star formation histories, chemical
evolution, and distances to these galaxies. These data will be placed
immediately into the Hubble Data Archive.

STIS 9708

STIS Pure Parallel Imaging Program: Cycle 11

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

STIS 9507

STIS/UV snapshot survey of bright AGN

We propose a UV spectroscopic snapshot survey of bright AGN,
quadrupling the number of Seyferts UV spectra and adding dozens of new
quasars, aimed at the following goals: beginenumerate em Finding the
relationship between the intrinsic luminosity of the AGN and the
maximum velocity {and width} of the outflow emanating from it, and
determining the frequency of outflows in low-z AGN as a function of
luminosity. em Surveying IGM absorption line systems in numerous new
sight-lines. em Identifying promising targets for observations with
the future highly sensitive Cosmic Origin Spectrograph. endenumerate A
35-minute snapshot with exposures in either the G140L or G230L will
yield spectra with a minimum S/N > 15 per resolution element at all
wavelengths for all our potential targets. This will allow us to be
sensitive to absorption lines to a limiting equivalent width of 0.3
Angstrom at the 3 Sigma level. In order to facilitate rapid
observational followup, we waive the data proprietary period entirely.


A Survey for Missing Baryons in Highly Ionized Intergalactic Gas at Low

The Space Telescope Imaging Spectrograph (CCD and MA1) was used to
observe six additional low-z QSOs with the STIS FUV E140M echelle mode
{7 km s^-1 resolution}. Combined with archival data, this will
increase the sample redshift path by a factor of ~7 compared to the
published data. With the echelle data, we will {1} measure the number
of O VI absorbers per unit redshift {dN/dz} and their minimum
cosmological mass density with a limiting equivalent width of W_Lambda
~50 mAngstrom , {2} examine whether the O VI absorption arises in
photoionized, collisionally ionized, or multiphase gas, and {3} study
the dependence of the O VI system properties on environment. In
addition to testing this prediction regarding the location of the
missing baryons, the data will have applications to many other topics
such as low-z LyAlpha absorbers and the physical properties and
abundances of gas in the Milky Way halo.


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.


The Physical Parameters of the Hottest, Most Luminous Stars as a
Function of Metallicity

We have obtained excellent, new ground-based blue optical and HAlpha
spectra of a sample of very early-type stars in the Magellanic Clouds
in order to measure their physical properties, for comparison with the
extensive data that exists for higher-metallicity Galactic stars. Our
aim is to understand how effective temperatures depend upon
metallicity {necessary in determining IMFs}, and to explore the
astrophysically interesting regime of stars of extreme temperatures,
masses, and luminosities. In order to do this, we need to measure the
stellar wind terminal velocities for our stars, necessary to constrain
the stellar models. These can only be measured with STIS/FUV on HST.
In addition, we will obtain higher spatial resolution data on the
HAlpha line for stars for which nebular contamination is significant
in our ground-based data. We also include several R136 stars with
excellent STIS/CCD data but which lack UV line measures. These new HST
data will provide important information about the strengths of stellar
winds at extreme luminosities and the calibration of the Wind
Momentum- Luminosity Relationship at lower metallicities. This
proposal was highly rated in Cycle 9, but only 4 snapshots were
obtained. We have completed the analysis of these plus additional data
from the archives, but need spectra of the remaining objects if we are
to answer the questions we pose.

WFPC2 9710

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans.

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.

WFPC2 9595


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


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

HSTAR 9055: FHST Update (U1,2FM) failures @ 164/10:59:36Z and
164/11:02:21 during results "2 failed" in
mnemonics QEBSTFG(0,1,2). At AOS, received two
ESB 901 message indicating both updates failed. Following
GS Acquisition (2,3,3) was successful. Under

HSTAR 9056: GS Re-acquisition (3,2,2) suffers LOL. GS Re-acquisition
achieved FL data valid 155/04:26:43Z but went to SSM
control @ 155/04:27:01Z. Sci Ini on the LOL recovery @
155/04:28:46Z and no further LOLs were seen up
to the scheduled 155/04:45:28Z PCPTERM. This event was uncovered by
OTA SE in review of PTAS processing error files
for the SA153N SMS. Under investigation.

HSTAR 9057: GS Acquisition (3,2,3) @ 156/14:11:59Z regress to FLBU
(3,0,3) due to SSLE on uncovered by OTA SE in
review of PTAS processing error files SA153N SMS. Under



                           SCHEDULED     SUCCESSFUL    FAILURE TIMES
GSacq               26                        26

FGS REacq 22 22 FHST Update 48 46 164/1059z, 164/1102z LOSS of LOCK


SpaceRef staff editor.