Status Report

NASA Hubble Space Telescope Daily Report #3414

By SpaceRef Editor

July 29, 2003

Filed under Hubble Space Telescope, Space Telescope Science Institute, US

HUBBLE SPACE TELESCOPE

DAILY REPORT # 3414

PERIOD COVERED: DOY 209

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.

HST 9382

A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS QSO
MgII-FeII Systems.

We have searched the first public release of SDSS QSO spectra for
low-z {z<1.65} metal absorption lines and found over 200 large rest
equivalent width MgII-FeII systems. Previously, we empirically showed
that such systems are good tracers of large neutral gas columns, with
~50% being classical damped Lyman alpha {DLA} systems {N_HI>=2*10^20
cm^-2}. Here we propose to follow up a well-defined subset of 79 of
them to search for DLAs with 0.47<z<1.60. Only QSOs brighter than
g’=19 were selected. The QSO emission and DLA absorption redshifts
were constrained to virtually eliminate data loss due to intervening
Lyman limit absorption. Consequently, we expect to discover ~40 new
DLAs, which is a three-fold increase in this redshift interval. This
will significantly improve our earlier low-z DLA statistical results
on their incidence, cosmological mass density, and N_HI distribution.
The results will also allow us to better quantify the empirical DLA —
metal-line correlation. With this improved understanding, the need for
follow-up UV spectroscopy will lessen and, with the release of the
final database of SDSS QSO spectra {an ~25-fold increase}, the number
of low-z DLAs could be increased arbitrarily. Thus, the power of the
large and statistically-sound SDSS database in combination with a
proven technique for finding low-z DLAs will, over the next few years,
essentially solve the problem of making an accurate determination of
the cosmic evolution of the neutral gas component down to z~0.4.

ACS/WFPC2 9488

Cosmic Shear – with ACS Pure Parallel Observations

The ACS, with greater sensitivity and sky coverage, will extend our
ability to measure the weak gravitational lensing of galaxy images
caused by the large scale distribution of dark matter. We propose to
use the ACS in pure parallel {non- proprietary} mode, following the
guidelines of the ACS Default Pure Parallel Program. Using the HST
Medium Deep Survey WFPC2 database we have measured cosmic shear at
arc-min angular scales. The MDS image parameters, in particular the
galaxy orientations and axis ratios, are such that any residual
corrections due to errors in the PSF or jitter are much smaller than
the measured signal. This situation is in stark contrast with
ground-based observations. We have also developed a statistical
analysis procedure to derive unbiased estimates of cosmic shear from a
large number of fields, each of which has a very small number of
galaxies. We have therefore set the stage for measurements with the
ACS at fainter apparent magnitudes and smaller, 10 arc-second scales
corresponding to larger cosmological distances. We will adapt existing
MDS WFPC2 maximum likelihood galaxy image analysis algorithms to work
with the ACS. The analysis would also yield an online database similar
to that in archive.stsci.edu/mds/

WFPC2 9592

WFPC2 CYCLE 11 Standard Darks

This dark calibration program obtains dark frames every week in order
to provide data for the ongoing 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 9595

WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt3/3

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

WFPC2 9596

WFPC2 CYCLE 11 INTERNAL MONITOR

This calibration proposal is the Cycle 11 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{gain 7 and gain 15}, a test for quantum efficiency in the CCDs, and a
monitor for possible buildup of contaminants on the CCD windows.

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.

NICMOS 9636

Cycle 11 NICMOS dark current, shading profile, and read noise monitoring
program

The purpose of this proposal is to monitor the dark current, read
noise, and shading profile for all three NICMOS detectors throughout
the duration of Cycle 11. This proposal is a continuation of PID 9321
which covers the period between the end of SMOV3B and the onset of
Cycle 11.

ACS 9675

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.

ACS/HRC 9686

Probing the Accretion Geometry of a Quiescent Black Hole

Advective accretion is invoked to explain low luminosity accretion
onto both stellar mass and supermassive black holes. There has been
much theoritcal activity, and controversy, but observational
constraints are weak. We have found considerable x-ray and optical
variability. The similarity of timescales and amplitudes, and the
emission line kinematics all suggest that the optical variability is
driven by x-ray illumination of the accretion disc. We now propose the
first simultaneous x-ray and optical observations to test if the
variations are correlated and measure relative amplitudes. Our program
will yield new constraints upon the models, as the strength of the
optical emission line response is sensitive to the unobservable EUV
spectrum, and to the x-ray emission geometry.

STIS 9708

STIS Pure Parallel Imaging Program: Cycle 11

This is the default archival pure parallel program for STIS during cycle
11.

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 9710

POMS Test Proposal: WFII backup parallel archive proposal

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

STIS 9786

The Next Generation Spectral Library

We propose to continue the Cycle 10 snapshot program to produce a Next
Generation Spectral Library of 600 stars for use in modeling the
integrated light of galaxies and clusters. This program is using the
low dispersion UV and optical gratings of STIS. The library will be
roughly equally divided among four metallicities, very low {[Fe/H] lt
-1.5}, low {[Fe/H] -1.5 to -0.5}, near-solar {[Fe/H] -0.3 to 0.1}, and
super-solar {[Fe/H] gt 0.2}, well-sampling the entire HR-diagram in
each bin. Such a library will surpass all extant compilations and have
lasting archival value, well into the Next Generation Space Telescope
era. Because of the universal utility and community-broad nature of
this venture, we waive the entire proprietary period.

ACS/HRC 9853

A Search for Young Binary Brown Dwarfs: Constraining Formation
Scenarios and Masses Through Multiplicity

We propose to use the Advanced Camera for Surveys / High Resolution
Camera to conduct a direct imaging multiplicity survey of 34 young
brown dwarfs in the nearest regions of recent star formation, the T
association Taurus-Auriga and the OB association Upper Scorpius. The
determined multiplicity fraction, the separation distribution, and the
mass ratio distribution will offer stringent observational contraints
on proposed brown dwarf formation scenarios. Moreover, the small
semi-major axes of known field and open cluster brown dwarf binaries
suggest the exciting possibility of our identifying several very close
binaries {< 15 AU}. Continued monitoring of these systems would yield,
on a decade timescale, the first dynamical mass estimates of T Tauri
brown dwarfs. With masses intermediate between those of stars and
planets, brown dwarfs offer our best hope of relating the reasonably
well understood processes of star formation to the less well
understood processes of planet formation.

ACS/WFC 9872

Optical Counterpart of the Neutron Star 1E 1207.4-5209 in PKS
1209-51/52 Supernova Remnant

Chandra observations of the Compact Central Object 1E 1207.4-5209 in
the PKS 1209-51/52 Supernova Remnant allowed us to discover the first
absorption lines in the thermal spectrum of a neutron star and the 424
millisecond period of this object. This first discovery of spectral
lines allows an opportunity to measure the gravitational redshift at
the surface of a NS and constrain the Equation of State of the
super-dense matter. The measured gravitational redshift depends on the
correct identification of the spectral lines. Multiwavelength
observations are needed to constrain the origin of the spectral lines.
We propose deep HST imaging observations to search for the optical
counterpart of this source and constrain the properties of this unique
object.

STIS/CCD/MA1 9874

Probing IGM Phases, Metals, and the Cosmic Web with New SDSS QSOs

We propose STIS G140L SNAPSHOT observations of 100 new z < 1 QSOs from
the Sloan Digital Sky Survey for studies of the IGM. These targets
will be chosen to simultaneously maximize IGM pathlength and to form
closely spaced groups of 2-8 QSO sightlines within 1 h^-1 Mpc of a
foreground galaxy. These observations will, in the long term, provide
a rich database of target QSOs for detailed study by COS of the IGM
phases, metallicity, and relationship to the large scale structure. In
the near term, these observations will detect up to 10 Lyman alpha
clouds with N_HI > 10^14 and 3 clouds with N_HI > 10^15, per target.
Thus they will provide an immediate test of filamentary structure in
the "cosmic web" within 1 h^-1 Mpc of galaxies. We ask for 22 minute
exposures for each target with STIS/G140L to obtain S/N = 5-16 for
these V = 16 – 18 QSOs. These observations will be sensitive to Lyman
alpha equivalent widths ranging from 300 mA for the brighter sources
to 600 mA at the fainter end. These targets represent a Deltaz
pathlength of 17 {at 50% yield}, with Deltaz = 10 in the range where
Lya, Lyb, and O VI lie in the HST band. These observations will also
refine predictions of the FUV flux of QSOs based on the larger SDSS
sample and will estimate the degree to which such factors as intrinsic
and Galactic extinction, variability, and intervening absorption can
be controlled. If successful, this technique could make
UV-prequalification SNAPs of QSOs obsolete, at a significant savings
of HST time. Our observations lie at the median duration for SNAPs,
and in the range most likely to be executed. Our program accomplishes
both near- and long-term goals at a relatively low investment of time,
and thus is ideally suited for a SNAP proposal. To ensure maximum
scientific return for our own purposes and for additional science
{HVCs, Galactic halo} we waive the right to a proprietary data period.

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
ideal.