Status Report

NASA Hubble Space Telescope Daily Report # 3404

By SpaceRef Editor
July 16, 2003
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HUBBLE SPACE TELESCOPE

DAILY REPORT # 3404

PERIOD COVERED: DOY 195

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.

STIS/CCD 9350

Intergalactic HeII absorption in CSO 118 = HS 1157+3143

We propose to observe the HeII Gunn-Peterson effect in the z = 3 quasar CSO
118,
which has been discovered in our SNAPSHOT survey to have a transparent line
of
sight. The aim is in particular to extend our knowledge about HeII
reionization
which has been observed to take place in the range z = 3.1 to z = 2.8. While
existing and future FUSE observations will cover the redshift range z < 2.9,
redshifts above 2.9 have been covered by HST with only 2 lines of sights.

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 systems.

STIS/MA2 9474

Intriguing Transient Sources in M87

We have found a remarkable number of transient point sources in M87. Within
the
jet itself we have observed dramatic changes in less than a year. The point
sources are seen well in the bluest regions of the spectrum, where we obtain
high spatial resolution, are free from cosmic ray artifacts and obtain
excellent
discrimination against the underlying old, red galaxy. They display a
variety of
unusual properties: one is brighter than any in the catalogue of novae in
M31;
several are very close to the jet; another hints at rapid variability. We
propose to investigate the population of transient sources in M87 and to
probe
the intrinsic jet variability on short timescales by taking images in the
near
UV. Do the sources show nova-type light curves? Is there a
decline-rate/luminosity relation? If yes, may we use it for distance
estimation,
as in Galactic novae, and hence constrain the still very important Virgo
distance. Are there very rapidly varying sources, flare stars or
gravitational
lenses? Is the variable stellar population related to the excess globular
cluster frequency in M87? Is there a population of flickering objects in and
around the jet, which may be responsive emission arising from their close
proximity to a BL Lac nucleus {viewed down the jet axis}? Can we find
variability in the jet itself indicative of light week length scales?

ACS 9482

ACS Pure Parallel Lyman-Alpha Emission Survey {APPLES}

Ly-alpha line emission is an efficient tool for identifying young galaxies
at
high redshift, because it is strong in galaxies with young stars and little
or
no dust — properties expected in galaxies undergoing their first burst of
star- formation. Slitless spectroscopy with the ACS Wide-Field Camera and
G800L
grism allows an unmatched search efficiency for such objects over the
uninterrupted range 4 <~ z <~ 7. We propose the ACS Pure Parallel Ly-alpha
Emission Survey {“APPLES”}, to exploit this unique HST capability and so
obtain the largest and most uniform sample of high redshift Ly-alpha
emitters
yet. Parallel observations will allow this survey to be conducted with
minimal
impact on HST resources, and we will place reduced images and extracted
spectra
in the public domain within three months of observation. We aim to find ~
1000
Ly-alpha emitters, 5 times the biggest current sample of Ly-alpha emitters.
This
unprecedented sample will provide robust statistics on the populations and
evolution of Ly-alpha emitters between redshifts 4–7; a robust measurement
of
the reionization redshift completely independent of the Gunn-Peterson
trough;
spatial clustering information for Ly-alpha emitters which would let us
probe
their bias function and hence halo mass as a function of redshift; many
galaxies
at redshift exceeding 6; and lower redshift serendipitous discoveries.

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 9613

STIS CCD Spectroscopic Flats C11

Obtain CCD flats on the STIS CCD in spectroscopic mode.

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.

STIS/CAL 9628

MAMA Sensitivity and Focus Monitor Cycle 11

Monitor sensitivity of each MAMA grating mode to detect any change due to
contamination or other causes. Also monitor the STIS focus in a
spectroscopic
and imaging mode.

NICMOS 9639

Photometric Stability

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

ACS 9649

ACS internal CTE monitor

The charge transfer efficiency {CTE} of the ACS CCD detectors will decline
as
damage due to on-orbit radiation exposure accumulates. This degradation will
be
closely monitored at regular intervals, because it is likely to determine
the
useful lifetime of the CCDs. All the data for this program is acquired using
internal targets {lamps} only, so all of the exposures should be taken
during
Earth occultation time {but not during SAA passages}. This program emulates
the
ACS pre-flight ground calibration and post-launch SMOV testing {program
8948},
so that results from each epoch can be directly compared. Extended Pixel
Edge
Response {EPER} and First Pixel Response {FPR} data will be obtained over a
range of signal levels for both the Wide Field Channel {WFC}, and the High
Resolution Channel {HRC}.

ACS 9658

ACS Earth Flats

This program will obtain sequences of flat field images by observing the
bright
Earth. Several UV filters from the interim calibration program {9564}
require
additional exposures to obtain the required illumination. A few UV filters
from
this program will be repeated to monitor for changes in the flat fields and
to
verify the interim results. Since no streaks are observed in the UV, the
wavelength coverage is extended to longer wavelengths in order to explore
the
severity of streaks in the flats from clouds in the FOV. We have added
exposures
for the HRC in the visible filters to verify the results derived from the
L-flat
campaign and to explore the severity of streaks. We have also added
exposures on
WFC using the minimum exposure time and using filters which will not
saturate
the brightest WFC pixel by more than 10 times the full well.

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 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.

NIC2 9801

Are OH/IR Stars the Youngest post-AGB stars? A NICMOS Imaging Survey

Essentially all well-characterized preplanetary nebulae {PPNe}– objects in
transition between the AGB and planetary nebula evolutionary phases – are
bipolar, whereas the mass-loss envelopes of AGB stars are strikingly
spherical.
In order to understand the processes leading to bipolar mass-ejection, we
need
to know at what stage of stellar evolution does bipolarity in the mass-loss
first manifest itself. We have recently hypothesized that most OH/IR stars
{evolved mass- losing stars with OH maser emission} are very young PPNe. We
are
conducting a multiwavelength survey program of imaging and spectroscopic
observations of such objects, using a large, morphologically unbiased sample
selected using IRAS 12-to-25 micron colors. Our ongoing HST/SNAP imaging
survey
of the optically bright half of this sample with WFPC2 and ACS is highly
successful: 19/32 objects observed are extended with bipolar/multipolar
shapes
{remaining objects are unresolved}. Slightly more than 50% of our sample are
optically too faint or undetected but have strong near-IR counterparts — we
therefore propose a NICMOS SNAPshot imaging survey of these optically-faint
OH/IR stars. These observations are crucial for determining how and when the
bipolar geometry asserts itself. The results from our NICMOS survey
{together
with the WFPC2/ACS survey} will allow us to draw general conclusions about
the
onset of bipolar mass-ejection during late stellar evolution. Our
complementary
program of interferometric mapping of the OH maser emission in our sources
is
yielding kinematic information with spatial resolution comparable to that
in the
HST images. The HST/radio data will provide crucial input for theories of
post-AGB stellar evolution. In addition, these data will also indicate
whether
the multiple concentric rings, "searchlight beams”, and truncated
equatorial
disks recently discovered with HST in a few PPNe, are common or rare
phenomena.

FLIGHT OPERATIONS SUMMARY:

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

COMPLETED OPS REQs: None

OPS NOTES EXECUTED: None

                           SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq               11                       11
FGS REacq               4                         4
FHST Update             17                       17
LOSS of LOCK

SIGNIFICANT EVENTS: None

SpaceRef staff editor.