Status Report

NASA Hubble Space Telescope Daily Report # 3383

By SpaceRef Editor
June 13, 2003
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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 9401

The ACS Virgo Cluster Survey

We propose the most comprehensive imaging survey to date of
low-redshift, early-type galaxies. Our goal is to exploit the
exceptional imaging capabilities of the ACS by acquiring deep images
— in the SDSS g^ and z^ bandpasses — for 163 E, S0, dE, dE, N and
dS0 galaxies in Virgo, the nearest rich cluster. This extraordinary
dataset would likely constitute one of the principal legacies of HST,
and would have widespread applications for many diverse areas of
astrophysics. Our immediate scientific objectives are threefold: {1}
measure metallicities, ages and radii for the many thousands of
globular clusters {GCs} in these galaxies, and use this information to
derive the protogalactic mass spectrum of each galaxy; {2} measure the
central luminosity and color profile of each galaxy, and use this
information to carry out a completely independent test of the merging
hierarchy inferred from the GCs, with the aid of N-body codes that
simulate the merger of galaxies containing massive black holes; and
{3} calibrate the z^ -band SBF method, measure Virgo’s 3-D structure,
and carry out the definitive study of the GC luminosity function’s
precision as a standard candle. Our proposed Virgo Cluster Survey will
yield a database of unprecedented depth, precision and uniformity, and
will enable us to study the record of galaxy and cluster formation in
a level of detail which will never be possible with more distant


Spatially Resolved Stellar Populations in Two z~2.5 Gravitational Arcs

We propose to use ACS and NICMOS to observe two gravitationally lensed
galaxies at z~2.5. We will combine these data with existing archival
and scheduled GTO observation to make spatially resolved maps of
color, dust, and age for these objects. We will then use these maps to
study the properties of individual star-forming regions within these
galaxies, to search for an underlying old stellar population between
the knots of active star formation, and to test previous HST and
ground-based studies which have hitherto relied on spatially
unresolved colors alone to study stellar population in high redshift
star-forming galaxies. Ours will be the first study of stellar
populations of Lyman Break Galaxies on sub-galactic scales, and will
give important new insights into the way that these high-$z$ galaxies
are assembled.

ACS 9454

The Nature of the UV Continuum in LINERs: A Variability Test

LINERs may be the most common AGNs, and the signposts of accretion
onto the massive black holes present in most galaxies. However, the
LINER spectrum is the result of UV excitation, and, in at least some
LINERs, a nuclear cluster of hot stars, rather than an AGN, dominates
the energetics in the UV. Thus, it is still unknown if the UV
continuum, or the optical emission lines it excites, have anything to
do with an AGN. The demographics and accretion physics of
low-luminosity AGNs hinge on this question. We propose to search for
variability in a sample of 17 LINERs with compact UV nuclei.
Variability can reveal an AGN component in the UV continuum, even when
its light is not dominant. We will test systematically the handful of
non-definitive reports of UV variability, and potentially quantify the
AGN contribution to the UV emission. Variability in all or most
objects will be strong evidence that LINERs mark dormant AGNs in most
galaxies. Alternatively, a general null detection of variability will
suggest that, even in LINERs with additional AGN signatures, the UV
continuum is stellar in origin. Contemporaneous monitoring with the
VLA/VLBA of 11 objects which have radio cores {five of which we
already know are radio-variable} will reveal the relations between UV
and radio variations. The UV-variable objects will be targeted for
future, better-sampled, monitoring.

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


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.

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 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.

WFPC2 9634

POMS Test Proposal: WFII targeted parallel archive proposal

The parallel opportunities available with WFPC2 in the neighborhood of
bright galaxies are treated in a slightly different way from the
normal pure parallels. Local Group galaxies offer the opportunity for
a closer look at young stellar populations. Narrow-band images in
F656N can be used both to identify young stars via their emission
lines, and to map the gas distribution in star-forming regions. Thus,
the filter F656N is added to the four standard filters. Near more
distant galaxies, up to about 10 Mpc, we can map the population of
globular clusters; for this purpose, F300W is less useful, and only
F450W, F606W, and F814W will be used.

ACS 9655

ACS Post-SMOV UV Contamination Monitor

A standard star field {NGC6681} is observed about once a month through
all the ACS broad band UV filters. NGC6681 hosts several UV spectro –
photometric standard stars for which accurate spectra have been {and
will continue to be} measured with STIS. The target cannot be observed
for three months from mid November through to mid February, so the
standard star GRW+70 will be observed twice in its stead. This
programme continues the UV sensitivity monitoring campaign {ACS SMOV
proposal 9010} of the HRC and SBC after the end of the SMOV period. An
SBC dark current measurement is taken as the last exposure of each SBC

ACS 9656

Stability of the ACS CCD: geometry, flat fielding, photometry

A moderately crowded stellar field, located ~6′ West of the centre of
the cluster 47 Tuc, is observed repeatedly {every three weeks with the
WFC, every other month with the HRC} in various filters, spending 1
orbit per epoch. Different filters will be used every time, so that
over the course of the year all filters will have been employed at
least twice. The most common filters will be checked more frequently.
The same field has been observed in the course of the SMOV phase and
the positions and magnitudes of the most prominent stars have been
accurately measured. Although the field is neither a proper
astrometric nor a proper photometric standard one, the positions and
magnitudes of the objects in it can be used to monitor any local and
large scale variations in the platescale and sensitivity of the
detectors. It should be noted that for the filters which have already
been used during the SMOV phase it will be sufficient to take one
single image, without CR-SPLIT, since the exposure time is always
short {20-30 sec} and there will be so many stars that the few of them
which are affected by cosmic rays can be discarded as outliers in the
photometry. For narrow and medium band filters not exercised on this
target in the SMOV phase, however, a baseline will have to be set.
This expenditure of time will apply to the current cycle only. At
variance with the approach used in SMOV, there is no need for large
telescope slews to place the same objects on opposite sides of the
detectors, thence allowing the programme to remain compact and
efficient. All exposure level parameters are set to their default
values, except for the amplifier gain of the WFC exposures in the
F606W band, which will be collected with the gain value of 2 for the
WFC for compatibility with the SMOV observations. The exposure time is
typically 30 seconds for the WFC, 60 sec for the HRC. No attempt will
be made to attain a predefined or the same orientation on the sky
amongst different epochs. Typically, for the WFC, five exposures will
be accommodated in one orbit. For the HRC, about 10 exposures can be
fitted within one orbit

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.


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.) None



                           SCHEDULED     SUCCESSFUL    FAILURE TIMES
GSacq               11                        11

FGS REacq 4 4 FHST Update 22 22 LOSS of LOCK


Updated Battery "Pressure Based" State of Charge equations on all four
CCS Strings (GSCA 663). Battery 2 and 6 coefficients are based on
recent battery capacity testing and a 9 Ampere per battery PSEA load.
Batteries 1, 3, 4, and 5 were also adjusted for a PSEA load of 9
Amperes per battery.

SpaceRef staff editor.